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  • 04. Solid Earth::04.08. Volcanology::04.08.01. Gases  (51)
  • 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas  (44)
  • 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks  (28)
  • 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics  (27)
  • Elsevier  (122)
  • Annual Reviews
  • 2005-2009  (122)
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  • 1
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    An expanded non-Arrhenian model for silicate melt viscosity: A treatment for metaluminous, peraluminous and peralkaline liquids (2007)
    Elsevier
    Details
    Publikationsdatum: 2020-10-29
    Beschreibung: We present new viscosity measurements for melts spanning a wide range of anhydrous compositions including: rhyolite, trachyte, moldavite, andesite, latite, pantellerite, basalt and basanite. Micropenetration and concentric cylinder viscometry measurements cover a viscosity range of 10−1 to 1012 Pas and a temperature range from 700 to 1650 °C. These new measurements, combined with other published data, provide a high-quality database comprising ∼800 experimental data on 44 well-characterized melt compositions. This database is used to recalibrate the model proposed by Giordano and Dingwell [Giordano, D., Dingwell, D. B., 2003a. Non-Arrhenian multicomponent melt viscosity: a model. Earth Planet. Sci. Lett. 208, 337–349] for predicting the viscosity of natural silicate melts. The present contribution clearly shows that: (1) the viscosity (η)–temperature relationship of natural silicate liquids is very well represented by the VFT equation [log η=A+B/ (T−C)] over the full range of viscosity considered here, (2) the use of a constant high-T limiting value of melt viscosity (e.g., A) is fully consistent with the experimental data, (3) there are 3 different compositional suites (peralkaline, metaluminous and peraluminous) that exhibit different patterns in viscosity, (4) the viscosity of metaluminous liquids is well described by a simple mathematical expression involving the compositional parameter (SM) but the compositional dependence of viscosity for peralkaline and peraluminous melts is not fully controlled by SM. For these extreme compositions we refitted the model using a temperature-dependent parameter based on the excess of alkalies relative to alumina (e.g., AE/SM). The recalibrated model reproduces the entire database to within 5% relative error (e.g., RMSE of 0.45 logunits).
    Beschreibung: Published
    Beschreibung: 42–56
    Beschreibung: reserved
    Schlagwort(e): Viscosity ; Model ; Silicate melts ; Metaluminous ; Peraluminous ; Peralkaline ; 04. Solid Earth::04.01. Earth Interior::04.01.05. Rheology ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 2
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    Experimental solidification of anhydrous latitic and trachytic melts at different cooling rates: the role of nucleation kinetics (2008)
    Elsevier
    Details
    Publikationsdatum: 2020-10-29
    Beschreibung: Two sets of cooling experiments were run at atmospheric conditions for two anhydrous starting latitic and trachytic melts: 1) five cooling rates (25, 12.5, 3, 0.5, and 0.125 °C/min) between 1300° and 800 °C, and 2) a 11 0.5 °C/min cooling rate from 1300 °C with quench temperatures at 1200°, 1100°, 1000° and 900 °C. Trachytic run-products are invariably glassy. Nucleation is also suppressed in the latitic run-products at the three highest 13 cooling rates. Conversely, in the 0.5 and 0.125 °C/min runs, latites have a crystal content of 90 vol.%. The 14 phases are: plagioclase, clinopyroxene, glass and iron-bearing oxide (in order of abundance). The variable 15 quench temperatures, investigated by coupling experiments with Pt-wire and Pt- capsule sample containers inset 2,again did not produce crystallization of trachyte, whereas latitic samples are characterized by 10 vol.% of oxides, pyroxenes and plagioclase (in order of appearance), at temperature b1000 °C. Effects of (preferential) heterogeneous nucleation on sample holders, of superheating degree, and chemical species loss during cooling are absent for both melt compositions. The difference of solidification paths between these two silicate melts can be ascribed only to their small chemical differences. In comparison with calculated equilibrium conditions all the experimental latitic and trachytic run-products revealed strong kinetic effects, interpretable in the light of the nucleation theory. The glass- forming ability (GFA) of trachyte is higher, whereas their critical cooling rate (Rc) is lower (b0.125 °C/min), in comparison to latitic melts (RcN0.5 °C/min). The experimental results carried out in this study can be applied to lava flows and domes; trachytic lavas are able to flow for longer period with respect to latitic ones in a metastable condition. Glass-rich terrestrial lavas, i.e. obsidians, can be the result of sluggish nucleation kinetics due to the relative high polymerisation of evolved silicate melts.
    Beschreibung: Published
    Beschreibung: 91-101
    Beschreibung: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): crystallization ; lava flows ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.02. Seismological data
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 3
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    Mechanisms for ground-surface fracturing and incipient slope failure associated with the 2001 eruption of Mt. Etna, Italy: analysis of ephemeral field data (2008)
    Elsevier
    Details
    Publikationsdatum: 2020-11-26
    Beschreibung: During the July^August 2001 eruption of Mt. Etna development of extensional fractures/faults and grabens accompanied magma intrusion and subsequent volcanic activity. During the first days of the eruption, we performed an analysis of attitude, displacement and propagation of fractures and faults exposed on the ground surface in two sites, Torre del Filosofo and Valle del Leone, located along the same fracture system in the region surrounding the Valle del Bove depression on the eastern flank of Mt. Etna. Fractures and faults formed as the consequence of a shallow intruding dyke system that fed the several volcanic centres developed along the fracture system. The investigated sites differ in slope attitude and in geometrical relationships between fractures and slopes. In particular, the fracture system propagated parallel to the gentle slope (67‡ dip) in the Torre del Filosofo area, and perpendicular to the steep slope (V25‡ dip) in the Valle del Leone area. In the Torre del Filosofo area, slight graben subsidence and horizontal extension of the ground surface by about 3 m were recorded. In the Valle del Leone area, extensional faulting forming a larger and deeper graben with horizontal extension of the ground surface by about 10 m was recorded. For the Valle del Leone area, we assessed a downhill dip of 14‡ for the graben master fault at the structural level beneath the graben where the fault dip shallows. These results suggest that dyke intrusion at Mount Etna, and particularly in the region surrounding the Valle del Bove depression, may be at the origin of slope failure and subsequent slumps where boundary conditions, i.e. geometry of dyke, slope dip and initial shear stress, amongst others, favour incipient failures.
    Beschreibung: Published
    Beschreibung: 281-294
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 3.2. Tettonica attiva
    Beschreibung: 3.5. Geologia e storia dei sistemi vulcanici
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): dykes ; extensional fractures ; grabens ; slope failures ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
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    Helium–strontium isotope constraints on mantle evolution beneath the Roman Comagmatic Province, Italy (2005)
    Elsevier
    Details
    Publikationsdatum: 2020-12-03
    Beschreibung: A study of the He isotopic ratios of fluid inclusions in olivine and pyroxene from the Roman Comagmatic Province (RCP),Italy, is presented together with 87Sr/86Sr isotope compositions of the whole rock or pyroxene phenocrysts. A clear covariation in He and Sr isotopes is apparent, with a strong northward increase in radiogenic He and Sr being evident. He and Sr isotopes ratios range from 3He/4He = 5.2 Ra and 87Sr/86Sr = 0.7056 in south Campania, to 3He/4He = 0.44 Ra and 87Sr/86Sr = 0.715905 in the northernmost Latium. Helium isotope ratios are significantly lower than MORB values and are among the lowest yet measured in subduction zone volcanism. The 3He/4He of olivine and pyroxene phenocryst-hosted volatiles appear to be little influenced by posteruptive processes and magma–crust interaction. The 3He/4He–87Sr/86Sr covariation is consistent with binary mixing between an asthenospheric mantle similar to HIMU ocean island basalts, and an enriched (radiogenic) mantle end member generated from subduction of the Ionian/Adriatic plate. The contribution of radiogenic He from metasomatic fluids and postmetasomatism radiogenic ingrowth in the wedge is strongly dependent on the initial He concentration of the mantle. Only when asthenosphere He concentrations are substantially lower than the MORB source mantle, and metasomatism occurred at the beginning of the subduction (f30 Ma), can ingrowth in the mantle wedge account for the 3He/4He of the most radiogenic basalts.
    Beschreibung: - European Social Fund - Scottish Universities - Carnegie Trust for the Universities of Scotland.
    Beschreibung: Published
    Beschreibung: 295–308
    Beschreibung: partially_open
    Schlagwort(e): Roman Comagmatic Province ; fluid inclusions ; helium ; strontium ; 04. Solid Earth::04.01. Earth Interior::04.01.03. Mantle and Core dynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes ; 04. Solid Earth::04.07. Tectonophysics::04.07.08. Volcanic arcs ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
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    Carbon dioxide degassing from Tuscany and Northern Latium (Italy) (2008)
    Elsevier
    Details
    Publikationsdatum: 2021-01-07
    Beschreibung: The CO2 degassing process from a large area on the Tyrrhenian side of central Italy, probably related to the input into the upper crust of mantle fluids, was investigated in detail through the geochemical study of gas emissions and groundwater. Mass-balance calculations and carbon isotopes show that over 50% of the inorganic carbon in regional groundwater is derived from a deep source highlighting gas−liquid separation processes at depth. The deep carbonate−evaporite regional aquifer acts as the main CO2 reservoir and when total pressure of the reservoir fluid exceeds hydrostatic pressure, a free gas phase separates from the parent liquid and escapes toward the surface generating gas emissions which characterise the study area. The distribution of the CO2 flux anomalies and the location of high PCO2 springs and gas emissions suggest that the storage and the expulsion of the CO2 toward the atmosphere are controlled by the geological and structural setting of the shallow crust. The average CO2 flux and the total amount of CO2 discharged by the study area were computed using surface heat flow, enthalpy and CO2 molality of the liquid phase circulating in the deep carbonate−evaporite aquifer. The results show that the CO2 flux varies from 1×104 mol y−1 km−2 to 5×107 mol y−1 km−2, with an average value of 4.8×106 mol y−1 km−2, about five times higher than the value of 1×106 mol y−1 derived by Kerrick et al. [Kerrick, D.M., McKibben, M.A., Seward, T.M., Caldeira, K., 1995. Convective hydrothermal CO2 emission from high heat flow regions. Chem. Geol. 121, 285–293] as baseline for terrestrial CO2 emissions. The total CO2 discharged from the study area is 0.9×1011 mol y−1, confirming that Earth degassing from Tyrrhenian central Italy is a globally relevant carbon source
    Beschreibung: Published
    Beschreibung: 89–102
    Beschreibung: 2.4. TTC - Laboratori di geochimica dei fluidi
    Beschreibung: 4.5. Degassamento naturale
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Earth degassing ; carbon dioxide ; CO2 flux ; groundwater ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
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    The Afragola settlement near Vesuvius, Italy: The destruction and abandonment of a Bronze Age village revealed by archaeology, volcanology and rock-magnetism (2009)
    Elsevier
    Details
    Publikationsdatum: 2021-06-15
    Beschreibung: Public works in progress in the Campanian plain north of Somma-Vesuvius recently encountered the remains of a prehistoric settlement close to the town of Afragola. Rescue excavations brought to light a Bronze Age village partially destroyed and buried by pyroclastic density currents (PDCs) of the Vesuvian Pomici di Avellino eruption (3.8 14C ka BP) and subsequently sealed by alluvial deposits. Volcanological and rockmagnetic investigations supplemented the excavations. Careful comparison between volcanological and archaeological stratigraphies led to an understanding of the timing of the damage the buildings suffered when they were struck by a series of PDCs. The first engulfed the village, located some 14 km to the north of the inferred vent, and penetrated into the dwellings without causing major damage. The buildings were able to withstand the weak dynamic pressure of the currents and deviate their path, as shown by the magnetic fabric analyses. Some later collapsed under the load of the deposits piled up by successive currents. Stepwise demagnetization of the thermal remanent magnetization (TRM) carried by potsherds embedded in the deposits yields deposition temperatures in the order of 260– 320 °C, fully consistent with those derived from pottery and lithic fragments from other distal and proximal sites. The fairly uniform temperature of the deposits is here ascribed to the lack of pervasive air entrainment into the currents. This, in turn, resulted from the lack of major topographical obstacles along the flat plain. The coupling of structural damage and sedimentological analyses indicates that the currents were not destructive in the Afragola area, but TRM data indicate they were still hot enough to cause death or severe injury to humans and animals. The successful escape of the entire population is apparent from the lack of human remains and from thousands of human footprints on the surface of the deposits left by the first PDCs. People were thus able to walk barefoot across the already emplaced deposits and escape the subsequent PDCs. The rapid cooling of the deposits was probably due to both their thinness and heat dissipation due to condensation of water vapour released in the mixture by magma–water interaction.
    Beschreibung: Published
    Beschreibung: 408–421
    Beschreibung: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Beschreibung: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): pyroclastic density current ; Bronze Age ; magnetic fabric ; deposition temperature ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    The effect of H2O on the viscosity of K-trachytic melts at magmatic temperatures (2007)
    Elsevier
    Details
    Publikationsdatum: 2020-10-29
    Beschreibung: Viscosity of hydrous trachytes from the Agnano Monte Spina eruption (Phlegrean Fields, Italy) has been determined at 1.0 GPa and temperatures between 1200 and 1400 °C using the falling sphere method in a piston cylinder apparatus. The H2O content in the melts ranged from 0.18 to 5.81 wt.%. These high-temperature hydrous viscosities, along with previous ones determined at low-temperature (anhydrous and hydrous) and at high-temperature (anhydrous), at 1 atm on the same melt composition, represent the only complete viscosity data set available for K-trachyticmelts, frommagmatic to volcanic conditions.Viscosity decreases with increasing temperature andwater content in the melt.At constant temperature, viscosity appears to significantly decreasewhen the first wt.% ofH2Ois added.At H2O content higher than 3 wt.% the effect of temperature on viscosity is slight. Moreover, the deviation from Arrhenian behaviour towards greater “fragility” occurs with increasing water content. We combined low- and high-temperature viscosities (also from literature) and parameterized themby the use of a modified Vogel–Fulcher–Tamman equation, which accommodates the non-Arrhenian temperature dependence ofmelt viscosity.Moreover, in order to explore the extent to which the improved knowledge of Agnano Monte Spina trachyte viscosity may affect simulation of volcanic eruption at Phlegrean Fields, we included our viscosity models in numerical simulations of magma flow and fragmentation along volcanic conduits. These simulations show that the new parameterizations (and hence the new equations) give stronger predictions in the temperature interval relevant for magmatic and eruptive processes.
    Beschreibung: Published
    Beschreibung: 124-137
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Viscosity ; Trachyte ; Falling sphere method ; Vogel–Fulcher–Tamman equation ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
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    Tectonic control on the eruptive dynamics at Mt. Etna Volcano (Sicily) during the 2001 and 2002–2003 eruptions (2005)
    Elsevier
    Details
    Publikationsdatum: 2020-12-15
    Beschreibung: The eruptive events of the July–August 2001 and October 2002–January 2003 at Mt. Etna provide new insights for reconstructing the complex geometry of the feeding system and their relationship to regional tectonics. The 2001 eruption took place mainly on the upper southern sector of the volcano. The eruption was preceded by a large earthquake swarm for a few days before its onset and accompanied by ground deformation and fracturing. The development of surface cracking along with the seismic pattern has allowed us to recognize three distinct eruptive systems (the SW–NE, NNW–SSE and N–S systems) which have been simultaneously active. Such eruptive systems are only the upper portions of a complex feeding system that was fed at the same time by two distinct magmas. The SW–NE and NNW–SSE systems, connected with the SE crater conduit, were fed by magma coming from depth, whereas the N–S system served instead as an ascending pathway for an amphibole-bearing magma residing in a shallow reservoir. The eruptive activity started again on October 2002 on the NE Rift Zone, where about 20 eruptive vents were aligned between 2500 and 1900 m a.s.l., and on the southern flank, from the central crater to the Montagnola. The onset of eruptive activity was accompanied by a seismic swarm. As in the 2001 eruptive event, two independent feeding systems formed, characterized by distinct magmas. The SW–NE system controlled the feeding of the Northeast Rift and was accommodated by left-lateral displacement along the WNW–ESE trending Pernicana Fault. The N–S system fed the eruptions on the southern flank. Moreover, the associated crustal deformation triggered seismic reactivation of tectonic structures in the eastern flank of the volcano and offshore. These two last eruptions indicate that at Mt. Etna the ascent of magma, as well as the accommodation of deformation, is strongly dominated by local extensional structures that are connected to a regional tectonic regime.
    Beschreibung: Published
    Beschreibung: 211-233
    Beschreibung: partially_open
    Schlagwort(e): extensional tectonics ; volcanic activity ; seismicity ; Sicily ; Mt. Etna ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 9
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    Dynamics of magma ascent and fragmentation in trachytic versus rhyolitic eruptions (2005)
    Elsevier
    Details
    Publikationsdatum: 2020-10-29
    Beschreibung: We have performed a parametric study on the dynamics of trachytic (alkaline) versus rhyolitic (calc-alkaline) eruptions by employing a steady, isothermal, multiphase non-equilibrium model of conduit flow and fragmentation. The employed compositions correspond to a typical rhyolite and to trachytic liquids from Phlegrean Fields eruptions, for which detailed viscosity measurements have been performed. The investigated conditions include conduit diameters in the range 30–90 m and total water contents from 2 to 6 wt%, corresponding to mass flow rates in the range 106–108 kg/s. The numerical results show that rhyolites fragment deep in the conduit and at a gas volume fraction ranging from 0.64 to 0.76, while for trachytes fragmentation is found to occur at much shallower levels and higher vesicularities (0.81–0.85). An unexpected result is that low-viscosity trachytes can be associated with lower mass flow rates with respect to more viscous rhyolites. This is due to the non-linear combined effects of viscosity and water solubility affecting the whole eruption dynamics. The lower viscosity of trachytes, together with higher water solubility, results in delayed fragmentation, or in a longer bubbly flow region within the conduit where viscous forces are dominant. Therefore, the total dissipation due to viscous forces can be higher for the less viscous trachytic magma, depending on the specific conditions and trachytic composition employed. The fragmentation conditions determined through the simulations agree with measured vesicularities in natural pumice clasts of both magma compositions. In fact, vesicularities average 0.80 in pumice from alkaline eruptions at Phlegrean Fields, while they tend to be lower in most calc-alkaline pumices. The results of numerical simulations suggest that higher vesicularities in alkaline products are related to delayed fragmentation of magmas with this composition. Despite large differences in the distribution of flow variables which occur in the deep conduit region and at fragmentation, the flow dynamics of rhyolites and trachytes in the upper conduit and at the vent can be very similar, at equal conduit size and total water content. This is consistent with similar phenomenologies of eruptions associated with the two magma types.
    Beschreibung: Published
    Beschreibung: 93-108
    Beschreibung: partially_open
    Schlagwort(e): trachytic magma ; conduit flow ; eruption dynamics and numerical simulations ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 10
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    The age of the Neapolitan Yellow Tu caldera-forming eruption (Campi Flegrei caldera-Italy) assessed by 40Ar/39Ar dating method (2005)
    Elsevier
    Details
    Publikationsdatum: 2020-12-17
    Beschreibung: The Neapolitan Yellow Tuff (NYT) is the product of the largest known trachytic phreatoplinian eruption. It covered an area larger than 1000 km2 with an estimated volume of about 40 km3 of erupted magma. During the course of the eruption a caldera collapsed within the previously formed Campanian Ignimbrite caldera. The resulting nested structure strongly influenced the following volcanic activity in the Campi Flegrei caldera. As previous dating of the NYT does not converge toward a unique result, a new set of 40Ar/39Ar age determinations has been carried out to better constrain the age of the eruption. Two variants of the 40Ar/39Ar dating method were applied to determine the age of the NYT eruption: (1) single-crystal total fusion (SCTF), on an individual phenocryst of feldspar, and (2) laser incremental heating (LIH), on bulk aliquots of feldspar phenocrysts. The results of the SCTF analyses show that the overall sample weighted mean age, derived from the conventional age calculation, is 15.6 ;0.8 ka. A weighted mean of the isochron age is 15.3 ;1.2 ka (2c), and has been assumed as the best indicator of age to be derived from the SCTF analyses. The LIH analyses results show that plateau ages vary from 15.4; 0.5 to 14.5; 0.5 ka. The overall weighted mean age of the isochron results is 14.9;0.4 ka (2c). This result has been assumed as the reference age for the NYT eruption, and agrees with the SCTF age. The new age obtained for the NYT deposits is of great relevance for the understanding of the evolution and the present state of the Campi Flegrei caldera and collocates the NYT in a crucial stratigraphical position to date the climatic oscillations that occurred between the Late Glacial and the Holocene.
    Beschreibung: Published
    Beschreibung: 157-170
    Beschreibung: partially_open
    Schlagwort(e): Neapolitan Yellow Tuff ; Campi Flegrei caldera ; 40Ar/39Ar dating method ; Geochronology ; Late Glacial ; Holocene ; 04. Solid Earth::04.04. Geology::04.04.02. Geochronology ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 11
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    Non-Newtonian rheology of crystal-bearing magmas and implications for magma ascent dynamics (2007)
    Elsevier
    Details
    Publikationsdatum: 2021-01-27
    Beschreibung: The eruptive dynamics of volcanic systems are largely controlled by the viscosity of deforming magma. Here we report the results of a series of high-temperature, high-pressure experiments at conditions relevant for volcanic conduits (250 MPa confining pressure and temperature between 500 °C and 900 °C) that were undertaken to investigate the rheology of magma with crystal fractions varying between 0.5 and 0.8 (50 to 80 wt.%) at different strain-rate conditions. The experiments demonstrate that the presence of crystals increases the relative viscosity (ratio between the viscosity of the mixture and the viscosity of the melt phase) of magmas and additionally induces a decrease of the relative viscosity with increasing strain-rate (shear thinning, non-Newtonian behavior). The experimental results, combined with existing data at low crystal fractions (0–0.3), were used to develop a semi-empirical parameterization that describes the variations of relative viscosity for crystal fractions between 0 and 0.8 and accounts for the complex non-Newtonian rheology of crystal-bearing magmas. The new parameterization, included into numerical models simulating the magma ascent dynamics, reveals that strain-rate-dependent rheology significantly modifies the dynamic behavior inside volcanic conduits, particularly affecting the magma fragmentation conditions.
    Beschreibung: Published
    Beschreibung: 402-419
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: JCR Journal
    Beschreibung: partially_open
    Schlagwort(e): magma rheology ; experimental deformation ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
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    Chemical evolution of thermal waters and changes in the hydrothermal system of Papandayan volcano (West Java, Indonesia) after the November 2002 eruption (2008)
    Elsevier
    Details
    Publikationsdatum: 2021-05-17
    Beschreibung: Papandayan is a stratovolcano situated in West Java, Indonesia. Since the last magmatic eruption in 1772,only few hydrothermal explosions have occurred. An explosive eruption occurred in November 2002 and ejected ash and altered rocks. The altered rocks show that an advanced argillic alteration took place in the hydrothermal system by interaction between acid fluids and rocks. Four zones of alteration have been defined and are limited in extension and shape along faults or across permeable structures at different levels beneath the active crater of the volcano. At the present time, the activity is centered in the northeast crater with discharge of low temperature fumaroles and acid hot springs. Two types of acid fluids are emitted in the crater of Papandayan volcano: (1) acid sulfate-chloride waters with pH between 1.6 and 4.6 and (2) acid sulfate waters with pH between 1.2 and 2.5. The water samples collected after the eruption on January 2003 reveal an increase in the SO4/Cl and Mg/Cl ratios. This evolution is likely explained by an increase in the neutralization of acid fluids and tends to show that water–rock interactions were more significant after the eruption. The evolution in the chemistry observed since 2003 is the consequence of the opening of new fractures at depth where unaltered (or less altered) volcanic rocks were in contact with the ascending acid waters. The high δ34S values (9–17‰) observed in acid sulfatechloride waters before the November 2002 eruption suggest that a significant fraction of dissolved sulfates was formed by the disproportionation of magmatic SO2. On the other hand, the low δ34S (−0.3–7‰) observed in hot spring waters sampled after the eruption suggest that the hydrothermal contribution (i.e. the surficial oxidation of hydrogen sulfide) has increased.
    Beschreibung: Published
    Beschreibung: 276-286
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: 2.4. TTC - Laboratori di geochimica dei fluidi
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Papandayan volcano ; Indonesia ; phreatic eruption ; hydrothermal system ; fluid geochemistry ; advanced argillic alteration ; gas geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 13
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    Magma-derived gas influx and water-rock interactions in the volcanic aquifer of Mt. Vesuvius, Italy (2005)
    Elsevier
    Details
    Publikationsdatum: 2021-06-25
    Beschreibung: We report in this paper a systematic investigation of the chemical and isotopic composition of groundwaters flowing in the volcanic aquifer of Mt. Vesuvius during its current phase of dormancy, including the first data on dissolved helium isotope composition and tritium content. The relevant results on dissolved He and C presented in this paper reveal that an extensive interaction between rising magmatic volatiles and groundwaters currently takes place at Vesuvius. Vesuvius groundwaters are dilute (mean TDS 2800 mg/L) hypothermal fluids (mean T 17.7°C) with a prevalent alkaline-bicarbonate composition. Calcium-bicarbonate groundwaters normally occur on the surrounding Campanian Plain, likely recharged from the Apennines. D and 18O data evidence an essentially meteoric origin of Vesuvius groundwaters, the contribution from either Tyrrhenian seawater or 18O-enriched thermal water appearing to be small or negligible. However, the dissolution of CO2-rich gases at depth promotes acid alteration and isochemical leaching of the permeable volcanic rocks, which explains the generally low pH and high total carbon content of waters. Attainment of chemical equilibrium between the rock and the weathering solutions is prevented by commonly low temperature (10 to 28°C) and acid-reducing conditions. The chemical and isotope (C and He) composition of dissolved gases highlights the magmatic origin of the gas phase feeding the aquifer. We show that although the pristine magmatic composition may vary upon gas ascent because of either dilution by a soil-atmospheric component or fractionation processes during interaction with the aquifer, both 13C/12C and 3He/4He measurements indicate the contribution of a magmatic component with a 13C 0‰ and R/Ra of 2.7, which is consistent with data from Vesuvius fumaroles and phenocryst melt inclusions in olivine phenocrysts. A main control of tectonics on gas ascent is revealed by data presented in this paper. For example, two areas of high CO2 release and enhanced rock leaching are recognized on the western (Torre del Greco) and southwestern (Torre Annunziata–Pompeii) flanks of Vesuvius, where important NE-SW and NW-SE tectonic structures are recognized. In contrast, waters flowing through the northern sector of the volcano are generally colder, less saline, and CO2 depleted, despite in some cases containing significant concentrations of magmaderived helium. The remarkable differences among the various sectors of the volcano are reconciled in a geochemical interpretative model, which is consistent with recent structural and geophysical evidences on the structure of Somma-Vesuvius volcanic complex.
    Beschreibung: -European Union, -Ministero dell’Universita’ e della Ricerca Scientifica e Tecnologica; -CNR–Gruppo Nazionale per la Vulcanologia.
    Beschreibung: Published
    Beschreibung: 963–981
    Beschreibung: partially_open
    Schlagwort(e): isotopes ; water chemistry ; dissolved gases ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 03. Hydrosphere::03.04. Chemical and biological::03.04.07. Radioactivity and isotopes ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 14
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    High-temperature viscosity measurements of hydrous albite liquid using in-situ falling sphere viscometry at 2.5 GPa (2007)
    Elsevier
    Details
    Publikationsdatum: 2020-10-29
    Beschreibung: In-situ falling-sphere viscometry using shadow radiography in a multianvil apparatus was conducted on a series of samples along the NaAlSi3O8–H2O join up to 2.8 wt.% H2O at the Spring-8 synchrotron radiation facility (Hyogo, Japan). This allowed us to determine viscosities normally too low to be measured at ambient pressure for hydrous silicate melts at high temperatures due to rapid devolatilization. Pressure was fixed at 2.5 GPa for all experiments allowing us to gauge the effect of chemical composition on viscosity. In particular, the series of samples allowed us to vary the melt's degree of polymerization while maintaining a constant Al to Si ratio. Our results show that, for all samples, viscosity decreases as a function of pressure between 1 atm and 2.5 GPa at 1550 °C, indicating that the pressure anomaly can still be observed as depolymerization of the melt increases from nominally 0 (dry albite liquid) to NBO/T=0.8 (assuming water speciation entirely as hydroxyl groups at experimental conditions). We also find that the magnitude of the decrease in viscosity over this pressure interval does not appear to be dependent on the amount of water in the melt (i.e., NBO/T). An explanation for this behavior might be that the molar volume, at least over this limited compositional range, is nearly constant and the effects of compression of these melts, though different in degree of polymerization, are similar.
    Beschreibung: Published
    Beschreibung: 2-9
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Viscosity ; Silicate melts ; High pressure ; 04. Solid Earth::04.01. Earth Interior::04.01.05. Rheology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 15
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    Physical properties of tuffs from a scientific borehole at Alban hills volcanic district (central Italy) (2008)
    Elsevier
    Details
    Publikationsdatum: 2020-11-17
    Beschreibung: Recent seismic swarms and hydrothermal activity suggest that the Quaternary volcanic complex of the Alban Hills may pose a threat to the city of Rome. A 350m scientific borehole was therefore drilled into this volcanic area to elucidate its inner structure for the first time. Wire-line logs were run in the borehole in order to characterize the physical properties of the rocks and their variations with depth. In particular, a detailed sonic log was run to measure the P-wave velocity from the well-head down to 110 m. To further investigate velocity changes, we carried out laboratory measurements of P and S elastic wave velocities and fluid permeability at effective pressures up to 70 MPa during both increasing and decreasing pressure cycles on selected core samples representative of the main volcanic units. Specifically, we studied samples from two pyroclastic units representative of two classes of volcanic deposits that are representative of the whole succession: (i) a coarse-grained, well-lithified facies (Pozzolane Rosse unit), containing abundant mm-to-cm lava clasts and crystals; and (ii) a fine-grained, matrix-supported pyroclastic deposit (Tufo Pisolitico di Trigoria unit), with rare lithic lava clasts and sparse pumice. Elastic wave velocities reveal significant differences between units and indicate how, within the same lithology, the different degree of lithification and presence of clasts can affect significantly physical property values. The mean laboratory value of the Pwave velocity for Pozzolane Rosse and Tufo Pisolitico di Trigoria units is respectively of 3.75 and 3.2 km/s at an effective pressure equivalent to that at the depth at which the sonic velocity was measured. Under increasing effective pressure a profound influence on the transport properties is observed. Permeability ranges from the order of 10−18 m2 for the Pozzolane Rosse unit to the order of 10−15 m2 for the Tufo Pisolitico di Trigoria unit, in good agreement with the shallow aquifer circulating in the shallower units.
    Beschreibung: Published
    Beschreibung: 161-169
    Beschreibung: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Scientific borehole ; Volcanic rocks ; Physical properties ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
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  • 16
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    The evolution of elastic moduli with increasing crack damage during cyclic stressing of a basalt from Mt. Etna volcano (2008)
    Elsevier
    Details
    Publikationsdatum: 2020-11-16
    Beschreibung: Volcanic edifices, such as Mt. Etna (Italy), are commonly subject to repeated cycles of stress over time due to the combination of magma emplacement from deep reservoirs to shallow depths and superimposed tectonic stresses. Such repeated stress cycles lead to anisotropic deformation and an increase in the level of crack damage within the rocks of the edifice and hence changes to their elastic moduli, which are a key parameter for reliable modelling of deformation sources. We therefore report results of changes in elastic moduli measured during increasing amplitude cyclic stressing experiments on dry and water-saturated samples of Etna basalt. In all experiments, the Young’s modulus decreased by approximately 30% over the total sequence of loading cycles, and the Poisson’s ratio increased by a factor of approximately 3 ± 0.5. Microseismicity, in terms of acoustic emission (AE) output, was also recorded throughout each experiment. Our results demonstrate that AE output only re-commences during any loading cycle when the level of stress where AE ceased during the unloading portion of the previous cycle is exceeded; a manifestation of the Kaiser stress-memory effect. In cycles where no AE output is generated, we also observe no change in elastic moduli. This result is observed for both mechanical and thermal stressing. Our results are interpreted in relation to measurements of volcano-tectonic seismicity and deformation at Mt. Etna volcano.
    Beschreibung: Published
    Beschreibung: 153-160
    Beschreibung: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): rock mechanics, elastic moduli, Etna basalt ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 17
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    TWODEE-2: A shallow layer model for dense gas dispersion on complex topography (2008)
    Elsevier
    Details
    Publikationsdatum: 2020-11-17
    Beschreibung: TWODEE-2 is a FORTRAN 90 code based on previous code (TWODEE). It is designed to solve the shallow water equations for fluid depth, depth-averaged horizontal velocities and depth-averaged fluid density. The shallow layer approach used by TWODEE-2 is a compromise between the complexity of CFD models and the simpler integral models. It can be used for forecasting gas dispersion near the ground and/or for hazard assessment over complex terrains. The inputs to the model are topography, terrain roughness, wind measurements from meteorological stations and gas flow rate from the ground sources. Optionally the model can be coupled with the output of a meteorological processor which generates a zero-divergence wind field incorporating terrain effects. Model outputs are gas concentration, depth-averaged velocity, averaged cloud thickness and dose. The model can be a useful tool for gas hazard assessment by evaluating where and when lethal concentrations for humans and animals can be reached.
    Beschreibung: Published
    Beschreibung: 667-674
    Beschreibung: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Dense gas transport ; Fortran code ; Gas hazard ; Computational model ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 05. General::05.01. Computational geophysics::05.01.99. General or miscellaneous ; 05. General::05.08. Risk::05.08.01. Environmental risk
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  • 18
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    Present-day stress-field modelling of southern Italy constrained by stress and GPS data (2009)
    Elsevier
    Details
    Publikationsdatum: 2020-11-16
    Beschreibung: The present-day tectonic setting of the Italian peninsula is very complex and involves competing geodynamic processes. In this context, southern peninsular Italy is characterised by extension along the Apenninic belt and in the Tyrrhenian margin and by transpression in the Apulia-Gargano region. The extension is well defined by means of geological, seismological, and contemporary stress data. For the latter only few data are available in the Apulia-Gargano region, leaving the state of stress in that area unresolved. Here we develop a finite-element model of the southern Italian region in order to predict the contemporary stress field. Our model predictions are constrained by model-independent observations of the orientation of maximum horizontal stress (SHmax), the tectonic regime, and the horizontal velocities derived from GPS observations. We performed a blind test with 31 newly acquired SHmax orientations in the Southern Apennines. These new data come from the analysis of borehole breakouts performed in 46 deep oil exploration wells ranging in depth from 1300 to 5500 m. The model results agree with the stress data that define a prevailing NW-SE SHmax orientation along the Apenninic belt and foredeep and thus are capable to predict the stress field where no stress information is available. We first analyse how much model predictions, based on older data, deviate from present-day stress data and then recalibrate the models based on our new stress data, giving insight into the resolution of both models and data. In the studied region, which is affected by low deformation rates, we find that geodetic data alone cannot resolve such low levels of deformation due to the high relative measurement errors. We conclude that both GPS and stress data are required to constrain model results.
    Beschreibung: This research was supported by the Italian Presidenza del Consiglio dei Ministri - Dipartimento della Protezione Civile (DPC) through the INGV-DPC project S1.
    Beschreibung: Published
    Beschreibung: 193-204
    Beschreibung: 2T. Deformazione crostale attiva
    Beschreibung: JCR Journal
    Beschreibung: open
    Schlagwort(e): Neotectonics ; Borehole-breakouts ; Southern Apennines ; Finite-element models ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.03. Geodesy::04.03.08. Theory and Models ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 19
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    Chemical and isotopic equilibrium between CO2 and CH4 in fumarolic gas discharges: generation of CH4 in magmatic-hydrothermal systems (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: The chemical and isotopic composition of fumarolic gases emitted from Nisyros Volcano, Greece,and of a single gas sample from Vesuvio, Italy, was investigated in order to determine the origin of methane (CH4) within two subduction-related magmatic-hydrothermal environments. Apparent temperatures derived from carbon isotope partitioning between CH4 and CO2 of around 340°C for Nisyros and 470°C for Vesuvio correlate well with aquifer temperatures as measured directly and/or inferred from compositional data using the H2O-H2-CO2-CO-CH4 geothermometer. Thermodynamic modeling reveals chemical equilibrium between CH4, CO2 and H2O implying that carbon isotope partitioning between CO2 and CH4 in both systems is controlled by aquifer temperature. N2/3He and CH4/3He ratios of Nisyros fumarolic gases are unusually low for subduction zone gases and correspond to those of midoceanic ridge environments. Accordingly, CH4 may have been primarily generated through the reduction of CO2 by H2 in the absence of any organic matter following a Fischer-Tropsch-type reaction. However, primary occurrence of minor amounts of thermogenic CH4 and subsequent re-equilibration with co-existing CO2 cannot be ruled out entirely. CO2/3He ratios and 13CCO2 values imply that the evolved CO2 either derives from a metasomatized mantle or is a mixture between two components, one outgassing from an unaltered mantle and the other released by thermal breakdown of marine carbonates. The latter may contain traces of organic matter possibly decomposing to CH4 during thermometamorphism.
    Beschreibung: European community
    Beschreibung: Published
    Beschreibung: 2321–2334
    Beschreibung: partially_open
    Schlagwort(e): fumarolic gases ; hydrothermal systems ; chemical and isotopic equilibrium ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 20
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    Water speciation and Sr isotopic exchange during water-melt interaction: a combined NMR-TIMS study on the Cretaio Tephra (Ischia Island,south Italy) (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: In order to improve the microscopic understanding of the water-magma interaction process during explosive volcanism,volcanic glasses representative of deposits with sedimentological characteristics suggesting different water/melt ratios were studied by a combination of the nuclear magnetic resonance (NMR) and TIMS methods. The glasses were separated from pumices of two surge layers and one fallout bed of the Cretaio Tephra (Ischia Island,Italy), which is the product of an explosive eruption that occurred at Ischia in the second century BC. The 29Si CP^MAS NMR experiments indicate the occurrence of 1H^29Si dipolar couplings in glasses from the phreatomagmatic activity, suggesting the presence of hydrogen atoms in proximity of silicon atoms. This feature is not detected in the glass from the deposit of the magmatic explosion. 1H MAS NMR spectra reveal different peaks attributed to different hydrous species characterized by different motional properties. These include ‘rigid’ H2O groups isolated in the glass structure, more mobile water species and possibly structural hydroxyl groups. 1H MAS NMR spectra recorded after deuteration experiments of the glass at a temperature up to 300‡C revealed that the exchange reactions of the D2O vapor with hydrogen were limited to the most mobile water species,possibly on vesicle surfaces or in channels. The hydrogen concentration linearly correlates with the 87Sr/86Sr isotope ratio in glasses,suggesting isotopic tracer exchanges between the Sr dissolved in the water vapor and the Sr in the silicon-oxygen network during hydration. It is proposed that the uprising melt interacted with a hydrothermal system of seawater-derived fluids,characterized by relatively high Sr isotopic composition.
    Beschreibung: Published
    Beschreibung: 311-320
    Beschreibung: partially_open
    Schlagwort(e): Ischia ; Cretaio Tephra ; Water-melt interaction ; Nuclear magnetic resonance ; Sr isotopes ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 21
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    Thermal and geochemical constraints on the ‘deep’ magmatic structure of Mt. Vesuvius (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: A review of available and new isotopic data on rocks from Mt. Vesuvius together with geophysical and mineralogical data allow us to define a ‘deep’ complex magmatic reservoir where mantle-derived magmas arrive, stagnate and differentiate, and to constrain a thermal model, which describes the history and present state of the reservoir and its surrounding rocks. The top of the reservoir is located at about 8 km depth, and it extends discontinuously down to 20 km depth. The reservoir is hosted in densely fractured continental crustal rocks, where magmas and crust can interact, and, according to thermal modeling results, has been fed more than once in the last 400 ka. The hypothesis of crustal contamination is favored by the high temperatures reached by crustal rocks as a consequence of repetitive intrusions of magma. From the ‘deep’ reservoir magmas rise to form ‘shallow’ magma chambers at different depths, as already known in the literature, where they can undergo low-pressure differentiation and mixing and feed the volcanic activity.
    Beschreibung: Published
    Beschreibung: 1-12
    Beschreibung: partially_open
    Schlagwort(e): Magmatic system ; Crustal contamination ; Thermal modeling ; Isotope geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 22
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    Evidence of active tectonics on a Roman aqueduct system (II–III century A.D.) near Rome, Italy (2006)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: In this paper we describe evidence of strong tectonic deformation affecting two aqueducts of Roman age (II–III century A.D.). The channels are located approximately 20 km northeast of Rome along the ancient Via Tiburtina. Brittle and ductile deformation affects these two structures, including extensional joint systems, NE-oriented faults, and horizontal distortion. This deformation is consistent with rightlateral movement on major N-striking faults, and represents the first evidence that tectonic deformation took place in historical times in the vicinity of Rome, with local strike–slip movement superimposed on a regional extensional fault system.
    Beschreibung: Published
    Beschreibung: 679–690
    Beschreibung: reserved
    Schlagwort(e): Strike–slip tectonics ; Active tectonics ; Geo-archaeology ; Rome ; Italy ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 23
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    Solubility and speciation of sulfur in silicate melts: The Conjugated Toop-Samis-Flood-Grjotheim (CTSFG) model (2006)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: A Conjugated Toop-Samis-Flood-Grjotheim (CTSFG) model is developed by combining the framework of the Toop-Samis polymeric approach with the Flood-Grjotheim theoretical treatment of silicate melts and slags. Electrically equivalent ion fractions are computed over the appropriate matrixes (anionic and cationic) in a Temkin notation for fused salts, and are used to weigh the contribution of the various disproportionation reactions of type: M2/pO(melt)+ 1/2S(gas)+M2/pS(melt)+1/2O2(gas) M2/po(melt)+1/2S2(gas)+3/2O2(gas)-M2/pSO4(melt)v being the charge of the generic Mp-1 cation. The extension of the anionic matrix is calculated in the framework of a previously developed polymeric model (Ottonello et al., 2001), based on a parameterization of Lux-Flood acid-base properties of melt components. Model activities follow the Raoultian behavior implicit in the Temkin notation, without the needs of introducing adjustable parameters. The CTSFG model is based on a large amount of data available in literature and exhibits a satisfactory heuristic capability, with virtually no compositional limits, as long as the structural role given to each oxide holds. The model may be employed to compute gas-melt equilibria involving sulfur and allows computing sulfide and sulfate contents of silicate melts whenever the fugacity of a gaseous sulfur species and oxygen are known. Alternatively, the model calculates the oxidation state of the system (i.e., oxygen fugacity), whenever an analytical determination of either sulfide/sulfate or ferrous/ferric ratios in the melt is provided. Calculated sulfide and sulfate capacities allow the estimates of sulfur abundance in various melts of geological interest, both under anhydrous and hydrous conditions or, alternatively, of fS2, given fO2 and the bulk sulfur content. In this case, fSO2 and fH2S may be eventually computed along the water-sulfur-melt boundary provided fH2O is known.
    Beschreibung: Published
    Beschreibung: 801-823
    Beschreibung: partially_open
    Schlagwort(e): sulfur ; silicate melts ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics
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    Crustal contamination and crystal entrapment during polybaric magma evolution at Mt.Somma-Vesuvius volcano, Italy: Geochemical and Sr isotope evidence (2007)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: New major and trace element analyses and Sr-isotope determinations of rocks from Mt. Somma–Vesuvius volcano produced from 25 ky BP to 1944 AD are part of an extensive database documenting the geochemical evolution of this classic region. Volcanic rocks include silica undersaturated, potassic and ultrapotassic lavas and tephras characterized by variable mineralogy and different crystal abundance, as well as by wide ranges of trace element contents and a wide span of initial Sr-isotopic compositions. Both the degree of undersaturation in silica and the crystal content increase through time, being higher in rocks produced after the eruption at 472 AD (Pollena eruption). Compositional variations have been generally thought to reflect contributions from diverse types of mantle and crust. Magma mixing is commonly invoked as a fundamental process affecting the magmas, in addition to crystal fractionation. Our assessment of geochemical and Srisotopic data indicates that compositional variability also reflects the influence of crustal contamination during magma evolution during upward migration to shallow crustal levels and/or by entrapment of crystal mush generated during previous magma storage in the crust. Using a variant of the assimilation fractional crystallization model (Energy Conservation– Assimilation Fractional Crystallization; [Spera and Bohrson, 2001. Energy-constrained open-system magmatic processes I: General model and energy-constrained assimilation and fractional crystallization (EC–AFC) formulation. J. Petrol. 999– 1018]; [Bohrson, W.A. and Spera, F.J., 2001. Energy-constrained open-system magmatic process II: application of energyconstrained assimilation–fractional crystallization (EC–AFC) model to magmatic systems. J. Petrol. 1019–1041]) we estimated the contributions from the crust and suggest that contamination by carbonate rocks that underlie the volcano (2 km down to 9–10 km) is a fundamental process controlling magma compositions at Mt. Somma–Vesuvius in the last 8 ky BP. Contamination in the mid- to upper crust occurred repeatedly, after the magma chamber waxed with influx of new mantle- and crustal-derived magmas and fluids, and waned as a result of magma withdrawal and production of large and energetic plinian and subplinian eruptions.
    Beschreibung: Published
    Beschreibung: 303– 329
    Beschreibung: reserved
    Schlagwort(e): Mt. Somma–Vesuvius volcano ; Sr isotopes ; Geochemistry ; Crustal contamination ; Mantle source ; Phenocryst entrapment ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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  • 25
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    Experimental determination of permeability of Neapolitan Yellow Tuff. (2007)
    Elsevier
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    Publikationsdatum: 2017-04-04
    Beschreibung: This paper presents and discusses the measurement of permeability of Neapolitan Yellow Tuff (NYT) samples obtained in the framework of a study concerning the phenomenon of bradyseism, i.e. the slow vertical movement of soil, in the Campi Flegrei caldera (Campania—Italy). Measurements have been performed under isothermal, non-isothermal and transient non-isothermal conditions using a specifically designed apparatus. Results of measurements of porosity of different samples are also reported. Experimental results in isothermal conditions show that the volume flux through the samples changes linearly with applied pressure. The values of permeability obtained turn out to be independent of the temperature and pressure gradients applied to the samples. This result is consistent with the fact that the permeability is a characteristic of the porous medium, and as such is not affected by temperature and pressure variation, at least in the range examined. The permeability values measured in our laboratories agree quite well with the ones measured in situ by the Agenzia Generale Italiana Petroli (AGIP) during a geothermal exploration of the Campi Flegrei area in 1980. An interesting, still unexplained phenomenon has been detected during transient phases when both pressure and temperature gradients were applied to the samples. The phenomenon consists in an enhancement of volume flux due to heat flux in the transient phase. The extra volume-flux disappears once the steady temperature gradient is reached.
    Beschreibung: Published
    Beschreibung: 125-136
    Beschreibung: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Beschreibung: 3.5. Geologia e storia dei sistemi vulcanici
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Campi Flegrei ; hydrothermal systems; ; resurgent calderas ; porous media ; hydraulic permeability ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
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  • 26
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    Changing conditions of magma ascent and fragmentation during the Etna 122 BC basaltic Plinian eruption: Evidence from clast microtextures (2007)
    Elsevier
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    Publikationsdatum: 2017-04-04
    Beschreibung: The Etna 122 BC basaltic eruption had two Plinian phases, each preceded and followed by weak phreatic and phreatomagmatic activity. This study infers changing eruption dynamics from density, grain size, and microtextural data from the erupted pyroclasts. The Plinian clasts show no evidence for quenching by external water; instead, all clasts are microvesicular and have high bubble number densities relative to the products of weaker basaltic explosive eruptions, suggesting that the 122 BC magma underwent coupled degassing linked to rapid ascent and decompression. This coupled degassing was probably enhanced by crystallization of abundant microlites, which increased the magma's effective viscosity during conduit ascent. Detailed measurements of vesicles and microlites show wide variations in number densities, size distributions, and shapes among clasts collected over narrow stratigraphic intervals. For such a diversity of clasts to be expelled together, portions of melt with contrasting ascent and degassing histories must have arrived at the fragmentation surface at essentially the same time. We suggest that a parabolic velocity profile across the conduit ensured that magma near the conduit walls ascended more slowly than magma along the axis, leading to a longer residence time and more advanced degrees of outgassing and crystallization in the marginal magma. In our model, accumulation of this outgassed, viscous magma along conduit walls reduced the effective radius of the shallow conduit and led to blockages that ended the Plinian phases.
    Beschreibung: Published
    Beschreibung: 333-354
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): basaltic Plinian ; Etna ; vesicles ; microlites ; conduit dynamics ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 27
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    Volumetric observations during paroxysmal eruptions at Mount Etna: pressurized drainage of a shallow chamber or pulsed supply? (2008)
    Elsevier
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    Publikationsdatum: 2017-04-04
    Beschreibung: The October 17 to November 5, 1999, eruption of Mount Etna’s Bocca Nuova crater emplaced a V15U106 m3 flow field. The eruption was characterized by 11 paroxysmal events during which intense Strombolian and lava fountain activity fed vigorous channelized PaPa flows at eruption rates of up to 120 m3 s31. Each paroxysm lasted between 75 and 450 min, and was separated by periods of less intense Strombolian activity and less vigorous (610 m3 s31) effusion. Ground-based, satellite- and model-derived volumetric data show that the eruption was characterized by two periods during which eruption rates and cumulative volume showed exponential decay. This is consistent with a scenario whereby the system was depressurized during the first eruptive period (October 17^23), repressurized during an October 24 pause, and then depressurized again during the second period (October 25^28). The imbalance between the erupted and supplied volumes mean that the two periods involved the collection of 1.5^5.7U106 m3 and 1.2^ 3.6U106 m3, respectively, or an increase in the time-averaged supply to 11.6^13.6 m3 s31 and 12.5^14.9 m3 s31. Two models are consistent with the observed episodic fountaining, derived volumetric trends and calculated volume imbalance: a magma collection model and a pulsed supply model. In the former case, depressurization of a shallow reservoir cause the observed volumetric trends and foam collapse at the reservoir roof powers fountaining. In the pulsing case, variations in magma flux account for pressurization^depressurization and supply the excess volume. Increases in rise rate and volatile flux, coupled with rapid exsolution during ascent, trigger fountaining. Limiting equations that define critical foam layer volumes and magma rise rates necessary for Hawaiian-style fountaining favor the latter model.
    Beschreibung: Published
    Beschreibung: 79-95
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 3.5. Geologia e storia dei sistemi vulcanici
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: 4.3. TTC - Scenari di pericolosità vulcanica
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Etna ; lava fountaining ; eruption rates ; lava channel ; foam layers ; rise rates ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.01. Earth Interior::04.01.05. Rheology ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.02. Exploration geophysics::04.02.05. Downhole, radioactivity, remote sensing, and other methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.07. Instruments and techniques ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 28
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    Hydrochemical dynamics of the “lake–spring” system in the crater of El Chichón volcano (Chiapas, Mexico) (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: El Chichón volcano (Chiapas, Mexico) erupted violently in March–April 1982, breaching through the former volcano–hydrothermal system. Since then, the 1982 crater has hosted a shallow (1–3.3 m, acidic (pH ∼ 2.2) and warm (∼ 30 °C) crater lake with a strongly varying chemistry (Cl/SO4=0–79 molar ratio). The changes in crater lake chemistry and volume are not systematically related to the seasonal variation of rainfall, but rather to the activity of near-neutral geyser-like springs in the crater (Soap Pool). These Soap Pool springs are the only sources of Cl for the lake. Their geyser-like behaviour with a long-term (months to years) periodicity is due to a specific geometry of the shallow boiling aquifer beneath the lake, which is the remnant of the 1983 Cl-rich (24,000 mg/l) crater lake water. The Soap Pool springs decreased in Cl content over time. The zero-time extrapolation (1982, year of the eruption) approaches the Cl content in the initial crater lake,meanwhile the extrapolation towards the future indicates a zero-Cl content by 2009±1. This particular situation offers the opportunity to calculate mass balance and Cl budget to quantify the lake–spring system in the El Chichón crater. These calculations show that the water balance without the input of SP springs is negative, implying that the lake should disappear during the dry season. The isotopic composition of lake waters (δD and δ18O) coincide with this crater lake-SP dynamics, reflecting evaporation processes and mixing with SP geyser and meteoric water. Future dome growth, not observed yet in the post-1982 El Chichón crater, may be anticipated by changes in lake chemistry and dynamics.
    Beschreibung: Published
    Beschreibung: 237–248
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: 2.4. TTC - Laboratori di geochimica dei fluidi
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): El Chichón volcano ; crater lake–Spring dynamics ; fluid geochemistry ; stable isotopes ; monitoring ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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  • 29
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    Vent conditions for expected eruptions at Vesuvius (2008)
    Elsevier
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    Publikationsdatum: 2017-04-04
    Beschreibung: Determining consistent sets of vent conditions for next expected eruptions at Vesuvius is crucial for the simulation of the sub-aerial processes originating the volcanic hazard and the eruption impact. Herewerefer to the expected eruptive scales and conditions defined in the frame of the EC Exploris project, and simulate the dynamics of magma ascent along the volcanic conduit for sub-steady phases of next eruptions characterized by intensities of the Violent Strombolian (VS), Sub-Plinian 2 (SP2), and Sub-Plinian 1 (SP1) scale. Sets of conditions for the simulations are determined on the basis of the bulk of knowledge on the past history of Vesuvius [Cioni, R., Bertagnini, A., Santacroce, R., Andronico, D., Explosive activity and eruption scenarios at Somma–Vesuvius (Italy): towards a new classification scheme. Journal of Volcanology and Geothermal Research, this issue.]. Volatile contents (H2O and CO2) are parameterized in order to account for the uncertainty in their expected amounts for a next eruption. In all cases the flow in the conduit is found to be choked, with velocities at the conduit exit or vent corresponding to the sonic velocity in the two-phase non-equilibrium magmatic mixture. Conduit diameters and vent mixture densities are found to display minimum overlapping between the different eruptive scales, while exit gas and particle velocities, as well as vent pressures, largely overlap. Vent diameters vary from as low as about 5 m for VS eruptions, to 35–55 m for the most violent SP1 eruption scale. Vent pressures can be as low as less than 1 MPa for the lowest volatile content employed of 2 wt.% H2O and no CO2, to 7–8 MPa for highest volatile contents of 5 wt.% H2O and 2 wt.% CO2 and large eruptive scales. Gas and particle velocities at the vent range from 100–250 m/s, with a tendency to decrease, and to increase the mechanical decoupling between the phases, with increasing eruptive scale. Except for velocities, all relevant vent quantities are more sensitive to the volatile content of the discharged magma for the highest eruptive scales considered.
    Beschreibung: Published
    Beschreibung: 359-365
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Vesuvius ; Numerical simulations ; Vent conditions ; Volcanic hazard ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 30
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    Carbon dioxide of Pu`u`O`o volcanic plume at Kilauea retrieved by AVIRIS hyperspectral data (2009)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: A remote sensing approach permits for the first time the derivation of a map of the carbon dioxide concentration in a volcanic plume. The airborne imaging remote sensing overcomes the typical difficulties associated with the ground measurements and permits rapid and large views of the volcanic processes together with the measurements of volatile components exolving from craters. Hyperspectral images in the infrared range (1900–2100 nm), where carbon dioxide absorption lines are present, have been used. These images were acquired during an airborne campaign by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) over the Pu`u` O`o Vent situated at the Kilauea East Rift zone, Hawaii. Using a radiative transfer model to simulate the measured up-welling spectral radiance and by applying the newly developed mapping technique, the carbon dioxide concentration map of the Pu`u` O`o Vent plume were obtained. The carbon dioxide integrated flux rate were calculated and a mean value of 396±138 t d−1 was obtained. This result is in agreement, within the measurements errors, with those of the ground measurements taken during the airborne campaign.
    Beschreibung: Published
    Beschreibung: 3192–3199
    Beschreibung: 1.10. TTC - Telerilevamento
    Beschreibung: JCR Journal
    Beschreibung: partially_open
    Schlagwort(e): Hyperspectral data ; Volcanic plume ; Carbon dioxide ; AVIRIS ; Kilauea ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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    Mercury gas emissions from La Soufrière Volcano, Guadeloupe Island (Lesser Antilles) (2009)
    Elsevier
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    Publikationsdatum: 2017-04-04
    Beschreibung: Quantifying mercury (Hg) emissions from active volcanoes is of particular interest for better constraining the global cycle and environmental impact of this highly toxic element. Here we report on the abundance of total gaseous (TGM=Hg0 (g)+HgII (g)) and particulate (Hg(p)) mercury in the summit gas emissions of La Soufrière andesitic volcano (Guadeloupe island, Lesser Antilles), where enhanced degassing of mixed hydrothermalmagmatic volatiles has been occurring since 1992 from the Southern summit crater.We demonstrate that Hg in volcanic plume occurs predominantly as gaseous mercury, with a mean TGM/Hg(p) mass ratio of ~63. Combining the mean TGM/H2S mass ratio of the volcanic plume (~3.2×10−6), measured close to the source vent, with the H2S plume flux (~0.7 t d−1), determined simultaneously, allows us to estimate a gaseous mercury emission rate of 0.8 kg yr−1 from La Soufrière summit dome. Somewhat lower TGM/Stot mass ratio in fumarolic gases from the source vent (4.4×10−7) suggests that plume chemical composition is not well represented by the emission source (fumaroles) due to chemical processes prior to (or upon) discharge. Current mercury emission from La Soufrìere volcano represents a very small contribution to the estimated global volcanic budget for this element.
    Beschreibung: Published
    Beschreibung: 276-282
    Beschreibung: 4.3. TTC - Scenari di pericolosità vulcanica
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Mercury ; Fumaroles ; Volcanic plume ; Trace metals ; Gaseous and particulate mercury ; Emission rate ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 32
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    Halogens in volcanic systems (2009)
    Elsevier
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    Publikationsdatum: 2017-04-04
    Beschreibung: The transport, degassing and atmospheric release of halogens from active volcanism on Earth have been the focus of increasing interest over the last few decades, and have recently been the subject of the 1st workshop on “Halogens in volcanic systems and their environmental impacts” that was held in December of 2007 at Yosemite Lodge in Yosemite National Park, California. As an introduction to this Chemical Geology special issue, collecting contributions from many of the participants at the workshop, we review here recent advances in this field, including experimental and theoretical investigations of halogen behaviour in volcanic and related magmatic systems. We discuss previous research on several aspects of halogen geochemistry, including halogen abundances in the mantle and magmas on Earth; the effects of halogens on phase equilibria and melt viscosities; their partitioning between melt and fluid phase(s) upon decompression, cooling and crystallisation of magmas in the Earth's crust; and their final atmospheric release as volcanic gases. The role of halogens in the genesis of hydrothermal systems and in the transport of ore-forming metals is also reviewed, and we discuss our current understanding of atmospheric processing of volcanic halogens in both the troposphere and stratosphere, and their consequent impacts. In spite of these recent advancements, our current understanding of halogen geochemistry at active volcanoes is still far too fragmentary, and the key questions that require answers from future research are summarised in our conclusions.
    Beschreibung: Published
    Beschreibung: 1-18
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Halogens ; Magmatic fluids ; Ore deposits ; Volcanic degassing ; Volcanic gas ; Atmospheric effects ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 33
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    Degassing of halogens from basaltic volcanism: Insights from volcanic gas observations (2009)
    Elsevier
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    Publikationsdatum: 2017-04-03
    Beschreibung: The currently available data set of S–Cl–F abundances in volcanic gas plumes and high-temperature fumarolic gas samples from basaltic volcanism is reviewed here in the attempt to derive constraints on the modes of halogen degassing from mafic silicate melts. Apart from large volcano-to-volcano variations, reflecting remarkable differences in volatile abundances in the source magmas, each of the explored volcanoes displays large changes of SO2/HCl and SO2/HF ratios with the style of volcanic activity, with HCl/HF staying fairly constant. Halogen abundances are low and SO2/HCl and SO2/HF are high when fresh (volatile-rich) magmas sustain degassing, as during explosive eruptions, at the onset of eruptive cycles, or shortly before paroxysmal events. Low SO2/HCl and SO2/HF ratios are instead characteristic of late stages of volcanic degassing, typically being observed in the concluding stages of basaltic eruptions, or during periods of reduced magma supply at persistently degassing volcanoes. These observations are taken as evidence of halogens being less keen to enter the gas phase (relative to S) during degassing of basaltic magmas; and quantitatively interpreted in light of a Rayleigh-type open-system degassing model. The model, though simple, quantitatively reproduces the range of volcanic gas compositions observed at basaltic volcanoes worldwide, and allows prediction of vapour/melt partitioning contrasts of factors ~9 and ~36 for the volatile couples S–Cl and S–F, respectively. These predictions require validation from appropriately designed experiments of halogen partitioning between magmatic vapours and silicate melts over a range of P–T–X conditions.
    Beschreibung: Published
    Beschreibung: 99-109
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Volcanic degassing ; Halogens ; Volcanic gases ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 34
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    Chronology of the 2007 eruption of Stromboli and the activity of the Scientific Synthesis Group (2009)
    Elsevier
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    Publikationsdatum: 2017-04-04
    Beschreibung: On 27 February 2007, at 12.49 GMT, a new eruption of Stromboli took place with the effusion of a lava flow from a fracture cutting the flank of the NE cone, which rapidly reached the sea. The eruption had been heralded by an increase in the amplitude of tremor and flank movement since at least the 14th of February. Short-term precursors were an increase in the rate of occurrence of small landslides within the “Sciara del Fuoco” scar on the North-western flank of the volcano. A new effusive vent opened at 18.30 GMT on the Sciara del Fuoco at an height of 400 m asl. The new lava emission caused the sudden termination of the summit flow and initiated a period of non-stationary lava outpouring which ended on 2 April, 2007. The eruption has been characterized by a rapid decrease in the eruption rate after the first days and subsequently by episodic pulse increases. On the 15th of March, the increase in lava outpouring, monitored by a thermal camera, heralded by 9 min the occurrence of a violent paroxysmal explosion with the formation of an impulsive eruption column and the emission of small pumices mingled with black scoriae. The pumice had a bulk composition similar to that of the lava and of the black scoriae, but with a distinct lower content of phenocrysts. A similar feature has been repeatedly observed during the major explosive paroxysms of Stromboli. Short term precursors of the paroxysm were recorded by strainmeter and tiltmeter stations. The volcano monitoring activity has been made by a joint team of researchers from the INGV sections of Catania, Napoli, Palermo and Rome, along with researchers from the Universities of Florence, Pisa, Roma Tre, and Palermo. The scientific activity was coordinated by a Synthesis Group made up by scientists responsible for the different monitoring techniques of INGV and Universities and by the volcanic experts of Commissione Nazionale Grandi Rischi of the Prime Minister Office (Civil Protection Department). The group made a daily evaluation of the state of the volcano and transmitted its recommendations to the Civil Protection Department (DPC). Several prevention measures were adopted by DPC, the main of which were the evacuation of the coast zone when strong acceleration of the Sciara del Fuoco slope motion (occurred twice) could led to a dangerous tsunami by flank collapse (as last occurred on 30 December 2002) and four days before the 15 March paroxysm when access was prohibited to the part of the volcano above 290 m asl.
    Beschreibung: Published
    Beschreibung: 123–130
    Beschreibung: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Stromboli volcano ; 2007 eruption ; scientific emergency management ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
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  • 35
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    Rapid morphological changes at the summit of an active volcano: reappraisal of the poorly documented 1964 eruption of Mount Etna (Italy) (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: While the eruptive record of Mount Etna is reasonably complete for the past 400 years, the activity of the early and late 1960s, which took place at the summit, is poorly documented in the scientific literature. From 1955 to 1971, the Central and Northeast Craters were the sites of long-lived mild Strombolian and effusive activity, and numerous brief episodes of vigorous eruptive activity, which led to repeated overflows of lava onto the external flanks of the volcano. A reconstruction of the sequence of the more important of these events based on research in largely obscure and nearly inaccessible sources permits a better understanding of the eruption dynamics and rough estimates of erupted volumes and of the changes to the morphology of the summit area. During the first half of 1964, the activity culminated in a series of highly dynamic events at the Central Crater including the opening of a fissure on the E flank of the central summit cone, lava fountains, voluminous tephra emission, prolonged strong activity with continuous lava overflows, and growth of large pyroclastic intracrater cones. Among the most notable processes during this eruption was the breaching of a section of the crater wall, which was caused by lateral pressure of lava ponding within the crater. Comparison with the apparently similar summit activity of 1999 allows us to state that (a) lava overflows from large pit craters at the summit are often accompanied by breaching of the crater walls, which represents a significant hazard to nearby observers, and that (b) eruptive activity in 1999 was much more complex and voluminous than in 1964. For 1960s standards however, the 1964 activity was the most important summit eruption in terms of intensity and output rates for about 100 years, causing profound changes to the summit morphology and obliterating definitively the former Central Crater.
    Beschreibung: Published
    Beschreibung: 203-218
    Beschreibung: partially_open
    Schlagwort(e): Mount Etna ; Summit eruption ; Crater morphology and Lava overflows ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 36
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    Pulsed lava effusion at Mount Etna during 2001 (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Effusion rate and degassing data collected at Mt. Etna volcano (Italy) in 2001 show variations occurring on time scales of hours to months. We use both long- and short-term data sets spanning January to August to identify this variation. The long data sets comprise a satellite- and ground-based time series of effusion rates, and the latter include field-based effusion rate and degassing data collected May 29–31. The satellite-derived effusion rates for January through August reveal four volumetric pulses that are characterized by increasing mean effusion rate values and lead up to the 2001 flank eruption. Peak effusion rates during these 23–57 day pulses were 1.2 m3 s-1 in Pulse 1 (1 Jan–4 Mar), 1.1 m3 s-1 in Pulse 2 (5 Mar–21 Apr), 4.2 m3 s-1 in Pulse 3 (24 Apr–18 Jun), 8.8 m3 s-1 in Pulse 4 (23 Jun–16 Jul), and 22.2 m3 s-1 during the flank eruption (17 Jul–9 Aug). Rank-order analysis of the satellite data shows that effusion rate values during the 2001 flank eruption define a statistically different trend than Etna's persistent activity from Jan 1 to Jul 17. Data prior to the flank eruption obey a power-law relationship that may define an effusion rate threshold of ~3–5 m3 s-1 for Etna's typical persistent activity. Our short-term data coincide with the satellite-derived peak effusion period of Pulse 3. Degassing (at-vent puff frequency) shows a general increase from May 29 to 31, with hour-long variations in both puff frequency and lava flow velocity (effusion rate). We identify five 3–14 h degassing periods that contain 26 shorter (19–126 min-long) oscillations. This variation shows some positive correlation with effusion rate measurements during the same time period. If a relationship between puff frequency and effusion rate is valid, we propose that their short-term variation is the result of changes in the supply rate of magma to the near-vent conduit system. Therefore, these short-term data provide some evidence that the clear weeks- to months-long variation in Etna's effusive activity (January–August 2001) was overprinted by a minutes- to hour-scale oscillation in shallow supply.
    Beschreibung: Published
    Beschreibung: 231-246
    Beschreibung: partially_open
    Schlagwort(e): effusion rate ; degassing ; oscillation ; shallow supply and Etna ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 37
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    H2S fluxes from Mt. Etna, Stromboli, and Vulcano (Italy) and implications for the sulfur budget at volcanoes (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: We present here new measurements of sulfur dioxide and hydrogen sulfide emissions from Vulcano, Etna, and Stromboli (Italy), made by direct sampling at vents and by filter pack and ultraviolet spectroscopy in downwind plumes. Measurements at the F0 and FA fumaroles on Vulcano yielded SO2/H2S molar ratios of 0.38 and 1.4, respectively, from which we estimate an H2S flux of 6 to 9 for the summit crater. For Mt. Etna and Stromboli, we found SO2/H2S molar ratios of 20 and 15, respectively, which combined with SO2 flux measurements, suggest H2S emission rates of 50 to 113 and 4 to 8, respectively. We observe that source and plume SO2/H2S ratios at Vulcano are similar, suggesting that hydrogen sulfide is essentially inert on timescales of seconds to minutes. This finding has important implications for estimates of volcanic total sulfur budget at volcanoes since most existing measurements do not account for H2S emission.
    Beschreibung: Published
    Beschreibung: 1861–1871
    Beschreibung: partially_open
    Schlagwort(e): H2S atmospheric budget ; volcanic degassing ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 38
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    Changes in fluid geochemistry and physico-chemical conditions of geothermal systems caused by magmatic input: The recent abrupt outgassing off the island of Panarea (Aeolian Islands, Italy) (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Hydrothermal systems and related vents can exhibit dramatic changes in their physico-chemical conditions over time as a response to varying activity in the feeding magmatic systems. Massive steam condensation and gas scrubbing processes of thermal fluids during their ascent and cooling cause further compositional changes that mask information regarding the conditions evolving at depth in the hydrothermal system. Here we propose a new stability diagram based on the CO2-CH4-CO-H2 concentrations in vapor, which aims at calculating the temperatures and pressures in hydrothermal reservoirs. To filter gas scrubbing effects, we have also developed a model for selective dissolution of CO2-H2S-N2-CH4-He-Ne mixtures in fresh and/or air-saturated seawater. This methodology has been applied to the recent (November 2002) crisis that affected the geothermal field off the island of Panarea (Italy), where the fluid composition and fluxes have been monitored for the past two decades. The chemical and isotopic compositions of the gases suggest that the volatile elements originate from an active magma, which feeds a boiling saline solution having temperatures of up to 350 C and containing 12 mol CO2 in vapor. The thermal fluids undergo cooling and re-equilibration processes on account of gas-water-rock interactions during their ascent along fracture networks. Furthermore, steam condensation and removal of acidic species, partial dissolution in cold air-saturated seawater and stripping of atmospheric components, affect the composition of the geothermal gases at shallow levels. The observed geochemical variations are consistent with a new input of magmatic fluids that perturbed the geothermal system and caused the unrest event. The present-state evolution shows that this dramatic input of fluids is probably over, and that the system is now tending towards steady-state conditions on a time scale of months.
    Beschreibung: Published
    Beschreibung: 3045-3059
    Beschreibung: partially_open
    Schlagwort(e): Submarine degassing ; geothermal system ; gas-water interaction ; gas geothermometry ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 39
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    Gas hazard assessment in a densely inhabited area of Colli Albani Volcano (Cava dei Selci, Roma) (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: The northwestern flank of the Colli Albani, a Quaternary volcanic complex near Rome, is characterised by high CO2 values and Rn activities in the groundwater and by the presence of zones with strong emission of gas from the soil. The most significant of these zones is Cava dei Selci where many houses are located very near to the gas emission site. The emitted gas consists mainly of CO2 (up to 98 vol) with an appreciable content of H2S (0.8). The He and C isotopic composition indicates, as for all fluids associated with the Quaternary Roman and Tuscany volcanic provinces, the presence of an upper mantle component contaminated by crustal fluids associated with subducted sediments and carbonates. An advective CO2 flux of 37 tons/day has been estimated from the gas bubbles rising to the surface in a small drainage ditch and through a stagnant water pool, present in the rainy season in a topographically low central part of the area. A CO2 soil flux survey with an accumulation chamber, carried out in February-March 2000 over a 12 000 m2 surface with 242 measurement points, gave a total (mostly conductive) flux of 61 tons/day. CO2 soil flux values vary by four orders of magnitude over a 160-m distance and by one order of magnitude over several metres. A fixed network of 114 points over 6350 m2 has been installed in order to investigate temporal flux variations. Six surveys carried out from May 2000 to June 2001 have shown large variations of the total CO2 soil flux (8/25 tons/day). The strong emission of CO2 and H2S, which are gases denser than air, produces dangerous accumulations in low areas which have caused a series of lethal accidents to animals and one to a man. The gas hazard near the houses has been assessed by continuously monitoring the CO2 and H2S concentration in the air at 75 cm from the ground by means of two automatic stations. Certain environmental parameters (wind direction and speed; atm P, T, humidity and rainfall) were also continuously recorded. At both stations, H2S and CO2 exceeded by several times the recommended concentration thresholds. The highest CO2 and H2S values were recorded always with wind speeds less than 1.5 m/s, mostly in the night hours. Our results indicate that there is a severe gas hazard for people living near the gas emission site of Cava dei Selci, and appropriate precautionary and prevention measures have been recommended both to residents and local authorities.
    Beschreibung: - GNV funded research project Gas Hazard of Colli Albani
    Beschreibung: Published
    Beschreibung: 81^94
    Beschreibung: partially_open
    Schlagwort(e): Colli Albani ; CO2 flux ; H2S ; gas hazard ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 40
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    Magma dynamics at mid-ocean ridges by noble gas kinetic fractionation: Assessment of magmatic ascent rates (2006)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Despite its impact in understanding oceanic crust formation and eruptive styles of related volcanism, magma dynamics at midocean ridges are poorly known. Here, we propose a new method to assess ascent rates of mid-ocean ridge basalt (MORB) magmas,as well as their pre- and sin-eruptive dynamics. It is based on the idea that a rising magma can reach a variable degree of both CO2 supersaturation in melt and kinetic fractionation among noble gases in vesicles in relation to its ascent rate through the crust. To quantify the relationship, we have used a model of multicomponent bubble growth in MORB melts, developed by extending the single-component model of Proussevitch and Sahagian [A.A. Proussevitch, D.L. Sahagian, Dynamics and energetics of bubble growth in magmas: analytical formulation and numerical modeling, J. Geophys. Res. 103 (1998), 18223–18251.] to CO2–He–Ar gas mixtures. After proper parameterization, we have applied it to published suites of data having the required features (glasses from Pito Seamount and mid-Atlantic ridges). Our results highlight that the investigated MORB magmas display very different ranges of ascent rates: slow rises of popping rock forming-magmas that cross the crust (0.01–0.5 m/s), slightly faster rates of energetic effusions (0.1–1 m/s), up to rates of 1–10 m/s which fall on the edge between lava effusion and Hawaiian activity. Inside a single plumbing system, very dissimilar magma dynamics highlight the large differences in compressive stress of the oceanic crust on a small scale. Constraints on how the systems of ridges work, as well as the characteristics of the magmatic source, can also be obtained. Our model shows how measurements of both the dissolved gas concentration in melt and the volatile composition of vesicles in the same sample are crucial in recognizing the kinetic effects and definitively assessing magma dynamics. An effort should be made to correctly set the studied samples in the sequence of volcanic submarine deposits where they are collected. Enhanced knowledge of a number of physical properties of gas-bearing MOR magmas is also required, mainly noble gas diffusivities, to describe multicomponent bubble growth at a higher confidence level.
    Beschreibung: Published
    Beschreibung: 138-158
    Beschreibung: partially_open
    Schlagwort(e): Bubble growth ; MORB ; Noble gas ; Kinetic fractionation ; Modeling ; 04. Solid Earth::04.04. Geology::04.04.07. Rock geochemistry ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 41
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    The 1980 pressure response and flank failure of Mount St. Helens (USA) inferred from seismic scaling exponents (2006)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: The cataclysmic 18 May 1980 eruption at Mount St. Helens was preceded by intense seismic activity marking the mechanical response of the volcanic edifice to interior pressurisation. This seismicity is analysed to yield the temporal change in the seismic scaling exponent, D, inferred from the seismic b-value, that in-turn is related to the seismic moment of an earthquake. Time evolution of D preceding the eruption onset reveals: (1) a major decrease in D occurring over only a few days at the end of March; (2) a steady but stepped decrease in D (steps ~5–10 days) occurring from the end of March to early May; (3) a sharp decrease in D in early May; and (4) steady low values of D occurring 2–3 days before the eruption onset. This response is interpreted as major ruptures, formed at the end of March, arresting and participating in, but not triggering the ultimate failure of the flank. Rather, the rate of interior fracturing slowed in the 2 months preceding the 18 May 1980 major blast, and the triggering of failure is consistent with interior gas overpressurisation. The occurrence of two swarms of low frequency seismic events and the high values of the harmonic tremor indicate the action of interior pressurisation on a cycle of 20–25 days. Solutions are applied to represent the harmonic interior pressurisation of the edifice by gas exsolving from the volcano core. The transient radial migration of overpressured gas may reduce the apparent strength of the edifice, and ultimately trigger failure of the flank. Importantly, this mechanism is capable of triggering flank failure both after multiple core pressurisation cycles have been sustained, and as core pressures are low and diminishing—and may be a minimum. These twin attributes are both apparent in the seismic record for Mount St. Helens, used as a proxy for the unrecorded timing and magnitude of gas pressurisation at the volcano core.
    Beschreibung: Published
    Beschreibung: 155-168
    Beschreibung: partially_open
    Schlagwort(e): seismicity ; scaling exponents ; haronic inflation ; pressurisation mechanics ; 04. Solid Earth::04.01. Earth Interior::04.01.04. Mineral physics and properties of rocks ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 42
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    Focused and diffuse effluxes of CO2 from mud volcanoes and mofettes south of Mt. Etna (Italy) (2007)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Several sites with anomalous emissions of carbon dioxide were investigated in the region south of Mt. Etna volcano in order to assess the types of emission (focused and/or diffuse), their surface extension and the total output of CO2. Most of the studied emissions are located on the southwest boundary of Mt. Etna, near the town of Paternò. They consist of three mud volcanoes (known as Salinelle), one spring with bubbling gas (Acqua Grassa) and one area of diffuse degassing (Peschería). Another site (Naftía Lake) with remarkable gas emissions (bubbling gas into a lake as well as adjacent areas of diffuse soil degassing) is located further southwest of Mt. Etna in an area of extinct Quaternary volcanism on the northwest margin of Hyblean Mts. In all of these areas the origin of the highest CO2 emissions is clearly magmatic, and degassing to the atmosphere occurs mostly through tectonic structures, probably at a regional scale. The magmatic source that feeds anomalous degassing in the above areas is likely to be the same that feeds volcanic activity at Mt. Etna. Focused degassing was measured at each emission vent using devices that measure the air speed, whereas diffuse soil degassing was measured using the accumulation chamber method. In total, 712 measurements were carried out (146 in focused degassing vents, 566 on diffuse degassing areas). Single CO2 output values ranged from 1.8 10−5 to 1.68 kg s−1. In the case of diffuse degassing areas, statistical analyses allowed to discriminate between biogenic CO2 and CO2 deriving from a magmatichydrothermal source. Only the efflux values from the latter source were considered in the output estimates. The total estimated output thus obtained was about 2.61 kg s−1, relevant to a total surface of about 146,500 m2 (which includes only the magmatic CO2 emissions). This value is comparable with that of most non-volcanic emissions from geothermal and/or faulted areas of centralsouthern Italy, as well with the CO2 output from some of the volcanic areas of Italy.
    Beschreibung: Istituto Nazionale di Geofisica e Vulcanologia; Dipartimento per la Protezione Civile.
    Beschreibung: Published
    Beschreibung: 46–63
    Beschreibung: 4.5. Degassamento naturale
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Mt. Etna ; mud volcanoes ; soil CO2 effluxes ; magmatic degassing ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 43
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    Environmental impact of magmatic fluorine emission in the Mt. Etna area (2007)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: The sustained and uninterrupted plume degassing at Mount Etna volcano, Southern Italy, represents the troposphere’s most prominent natural source of fluorine. Of the ~ 200 Mg of fluorine (as HFg) emitted daily by the volcano, 1.6±2.7 Mg are deposited by wet and dry deposition. Fluorine-deposition via volcanic ash, here characterised for the first time, can be quite significant during volcanic eruptions (i.e. 60 Mg of fluorine were deposited during the 2001 eruption through volcanic ash, corresponding to ~ 85% of the total fluorine deposition). Despite the fact that these depositions are huge, the fate of the deposited fluorine and its impact on the environment are poorly understood. We herein present original data on fluorine abundance in vegetation (Castanea Sativa and Pinus Nigra) and andosoils from the volcano’s flank, in the attempt to reveal the potential impact of volcanogenic fluorine emissions. Fluorine contents in chestnut leaves and pine needles are in the range 1.8-35 µg/g and 2.1-74 µg/g respectively; they exceed the typical background concentrations in plants growing in rural areas, but fall within the lower range of typical concentrations in plants growing near high fluorine anthropogenic emission sources. The rare plume fumigations on the lower flanks of Mt Etna (distance 〉 4 km from summit craters) are probably the cause of the “undisturbed” nature of Etnean vegetation: climatic conditions, which limit the growth of vegetation on the upper regione deserta, are a natural limit to the development of more severe impacts. High fluorine contents, associated with visible symptoms, were only measured in pine needles at three sites, located near recently-active (2001 to 2003) lateral eruptive fractures. Total fluorine contents (FTOT) in the Etnean soils have a range of 112-341 µg/g, and fall within the typical range of undisturbed soils; fluorine extracted with distilled water (FH2O) have a range of 5.1 to 61 µg/g and accounts for 2-40 % of FTOT. FH2O is higher in topsoils from the eastern flank (downwind), while it decreases with depth in soil profiles and on increasing soil grain size (thereby testifying to its association with clay-mineral-rich, fine soil fractions). The fluorine adsorption capacity of the andosoils acts as a natural barrier that protects the groundwater system.
    Beschreibung: Published
    Beschreibung: 87-101
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: 4.5. Degassamento naturale
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Mt. Etna ; Fluorine ; environmental volcanology ; impact of volcanic F ; soils ; vegetation ; volcanic ash ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 03. Hydrosphere::03.03. Physical::03.03.01. Air/water/earth interactions ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 05. General::05.08. Risk::05.08.01. Environmental risk
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  • 44
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    Gas geochemistry as a tool to investigate the Earth's degassing through volcanic and seismic areas: The soul of the 8th International Conference on Gas Geochemistry (2007)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Introduction of a special issue of the journal
    Beschreibung: no abstract
    Beschreibung: Published
    Beschreibung: 1-4
    Beschreibung: 4.5. Degassamento naturale
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Earth's degassing ; volcanic areas ; seismic areas ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 45
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    Halogen diffusion in a basaltic melt (2007)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: The diffusion of the halogens fluorine, chlorine, and bromine was measured in a hawaiitic melt from Mt. Etna at 500 MPa and 1.0 GPa, 1250 to 1450 ºC at anhydrous conditions; the diffusion of F and Cl in the melt was also studied with about 3 wt% of dissolved water. Experiments were performed using the diffusion-couple technique in a piston cylinder. Most experiments were performed with only one halogen diffusing between the halogen-enriched and halogen-poor halves of the diffusion couple, but a few experiments with a mixture of halogens (F, Cl, Br) were also performed in order to investigate the possibility of interactions between the halogens during diffusion. Fluorine and chlorine diffusivity show a very similar behavior, slightly diverging at low temperature. Bromine diffusion is a factor of about 2 to 5 lower than the other halogens in this study. Diffusion coefficients for fluorine range between 2.3x10−11 and 1.4x10−10 m2s−1, for chlorine between 1.1x10−11 and 1.3x10−10 and for bromine between 9.4x10−12 and 6.8x10−11 m2s−1. No pressure effect was detected at the conditions investigated. In experiments involving mixed halogens, the diffusivities appear to decrease slightly (by a factor of ~ 3), and are more uniform among the three elements. However, activation energies for diffusion do not appear to differ between experiments with individual halogens or when they are all mixed together. The effect of water increases the diffusion coefficients of F and Cl by no more than a factor of 3 compared to the anhydrous melt (DF = 4.0x10−11 to 1.6x10−10 m2s−1; DCl = 3.0x10−11 to 1.9x10−10 m2s−1). Comparing our results to the diffusion coefficients of other volatiles in nominally dry basaltic melts, halogen diffusivities are about one order of magnitude lower than H2O, similar to CO2, and a factor of ~5 higher than S. The contrasting volatile diffusivities may affect the variable extent of volatile degassing upon melt depressurization and vesiculation, and can help our understanding of the compositions of rapidly grown magmatic bubbles.
    Beschreibung: NSERC Discovery grant INGV-DPC 2004-2006 Projects (V3_6 – Etna)
    Beschreibung: Published
    Beschreibung: 3570-3580
    Beschreibung: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Diffusion ; Halogens ; Basalt ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 46
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    Belt bending driven by lateral bending of subducting lithospheric slab: geophysical evidences from the northern Apennines (Italy) (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Many of the mountain belts displaying a curved shape are "oroclines", i.e. are produced after progressive bending of an originally straight fold and thrust belt. The bending process was previously explained as a consequence of several possible events taking place in the crustal orogenic wedge, such as occurrence of obstacles, non-coaxial deformation, and mouvements on wrench faults. Recent paleomagnetic results from the northern Apenninic Arc document that this belt is properly an orocline and results from Late Messinian-Early Pliocene bending of a Messinian straight belt-foredeep system. Tomographic images in turn show the presence of a high-velocity body, interpreted as subducted slab, in the upper mantle beneath the northern Apennines, between 35 and 670 km depth. Down to 100 km, this body displays an arcuate shape which closely mirrors the geological outlines, while it appears to be straight (and parallel to the Messinian pre-rotated belt) at depth. We explore here the possibility that the arcuate shape of the northern Apennines is a consequence, closely following in time, on much deeper processes than previously suggested, i.e. the lateral bending of the subducting Adriatic plate.
    Beschreibung: Published
    Beschreibung: 53-64
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): paleomagnetism ; seismic tomography ; Northern Apennines ; orocline ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 47
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    Transpressive strain on the Lipari–Vulcano volcanic complex and dynamics of the “La Fossa” cone (Aeolian Islands, Sicily) revealed by GPS surveys on a dense network (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Ground deformation resulting from the last two GPS surveys carried out in March 2006 and September 2007 on the Lipari–Vulcano volcanic complex are analyzed. Data inversion was performed by Genetic Algorithms approach, using the horizontal strain measured on 258 GPS baselines, in order to avoid bias due to the ambiguity in fixing the reference system and to disregard the vertical deformation of the “La Fossa” cone. There are two networks in this area: the main Lipari–Vulcano network and the denser Vulcano–Nord one. Surveying strategies adopted for the main network during the latest surveys allowed long baselines, from Lipari and Vulcano to the surrounding permanent stations in the southern Tyrrhenian, to be processed with reliable accuracy. The fast-static strategy was instead adopted to survey the Vulcano–Nord network. Data from the main Lipari–Vulcano network has been processed in the ITRF05 frame and also in a local reference frame together with the Vulcano–Nord data. A significant Northward motion of Vulcano island with respect to the ITRF05 has been detected. This motion abruptly decreases in the northern part of Vulcano, suggesting a decoupling of the main Vulcano island from the rest of the volcanic complex. The analysis in the local reference frame evidenced a relative SSE-ward motion of Lipari and Northern part of Vulcano, with respect to the central and southern Vulcano. This comparison also highlights a local uplift of the “La Fossa” cone. In addition, a strain tensor analysis was performed, which highlighted a main NNE–SSW contraction and a minor ESE–WNW extension detected only on the southern part of Vulcano. This results are in agreement with a transpressive kinematics of the Lipari–Vulcano volcanic complex, with a main dextral component of displacement along a NW–SE striking structure.
    Beschreibung: Published
    Beschreibung: 64-70
    Beschreibung: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Volcano-tectonics ; Modeling ; ground deformation ; Tyrrhenian sea ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.03. Geodesy::04.03.08. Theory and Models ; 04. Solid Earth::04.03. Geodesy::04.03.09. Instruments and techniques ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.08. Volcanic arcs
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 48
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    Middle Pleistocene to Holocene activity of the Gondola Fault Zone (Southern Adriatic Foreland): deformation of a regional shear zone and seismotectonic implications (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Recent seismicity in and around the Gargano Promontory, an uplifted portion of the Southern Adriatic Foreland domain, indicates active E–W strike-slip faulting in a region that has also been struck by large historical earthquakes, particularly along the Mattinata Fault. Seismic profiles published in the past two decades show that the pattern of tectonic deformation along the E–W-trending segment of the Gondola Fault Zone, the offshore counterpart of the Mattinata Fault, is strikingly similar to that observed onshore during the Eocene–Pliocene interval. Based on the lack of instrumental seismicity in the south Adriatic offshore, however, and on standard seismic reflection data showing an undisturbed Quaternary succession above the Gondola Fault Zone, this fault zone has been interpreted as essentially inactive since the Pliocene. Nevertheless, many investigators emphasised the genetic relationships and physical continuity between the Mattinata Fault, a positively active tectonic feature, and the Gondola Fault Zone. The seismotectonic potential of the system formed by these two faults has never been investigated in detail. Recent investigations of Quaternary sedimentary successions on the Adriatic shelf, by means of very high-resolution seismic–stratigraphic data, have led to the identification of fold growth and fault propagation in Middle–Upper Pleistocene and Holocene units. The inferred pattern of gentle folding and shallow faulting indicates that sediments deposited during the past ca. 450 ka were recurrently deformed along the E–W branch of the Gondola Fault Zone. We performed a detailed reconstruction and kinematic interpretation of the most recent deformation observed along the Gondola Fault Zone and interpret it in the broader context of the seismotectonic setting of the Southern Apennines-foreland region. We hypothesise that the entire 180 km-long Molise–Gondola Shear Zone is presently active and speculate that also its offshore portion, the Gondola Fault Zone, has a seismogenic behaviour.
    Beschreibung: Study supported by ISMAR-CNR projects EUROSTRATAFORM (EVK3-CT-2002-00079) and “Rischi Sottomarini”(GNDT 2000–2004) and by the Project S2 funded in the framework of the 2004–2006 agreement between the Italian Department of Civil Protection and INGV (Research Unit 2.4). This is ISMAR-CNR (Bologna) contribution n. 1570.
    Beschreibung: Published
    Beschreibung: 110-121
    Beschreibung: 3.2. Tettonica attiva
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Quaternary ; Foreland deformation ; Active fault ; Adriatic Sea ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.04. Geology::04.04.04. Marine geology ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 49
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    Intrusion of eccentric dikes: The case of the 2001 eruption and its role in the dynamics of Mt. Etna volcano (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: The 2001 eruption represents one of the most studied events both from volcanological and geophysical point of view on Mt. Etna. This eruption was a crucial event in the recent dynamic of the volcano, marking the passage from a period (March 1993 – June 2001) of moderate stability with slow, continuous flank sliding and contemporaneous summit eruptions, to a period (July 2001 to present) of dramatically increased flank deformations and flank eruptions. We show new GPS data and high precision relocation of seismicity in order to demonstrate the role of the 2001 intrusive phase in this change of the dynamic regime of the volcano. GPS data consist of two kinematic surveys carried out on 12 July, a few hours before the beginning of the seismic swarm, and on 17 July, just after the onset of eruptive activity. A picture of the spatial distribution of the sin-eruptive seismicity has been obtained using the HypoDD relocation algorithm based on the double-difference (DD) technique. Modeling of GPS measurements reveal a southward motion of the upper southern part of the volcano, driven by a NNW-SSE structure showing mainly left-lateral kinematics. Precise hypocenter location evidences an aseismic zone at about sea level, where the magma upraise was characterized by a much higher velocity and an abrupt westward shift, revealing the existence of a weakened or ductile zone. These results reveal how an intrusion of a dike can severely modify the shallow stress field, triggering significant flank failure. In 2001, the intrusion was driven by a weakened surface, which might correspond to a decollement plane of the portion of the volcano affected by flank instability, inducing an additional stress testified by GPS measurements and seismic data, which led to an acceleration of the sliding flanks.
    Beschreibung: In press
    Beschreibung: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Beschreibung: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Beschreibung: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 3.2. Tettonica attiva
    Beschreibung: 3.5. Geologia e storia dei sistemi vulcanici
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: 4.2. TTC - Scenari e mappe di pericolosità sismica
    Beschreibung: 4.3. TTC - Scenari di pericolosità vulcanica
    Beschreibung: 4.4. Scenari e mitigazione del rischio ambientale
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Stress release ; Dike ; Volcano-tectonics ; Flank instability ; Mount Etna ; Instrumental monitoring ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 50
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    Structural features of the 2007 Stromboli eruption (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: On 27 February 2007, two NE–SW and NNW–SSE dike-fed effusive vents opened to the North (at 650 and 400 m above sea level, asl) of the summit craters at Stromboli, forming a fissure parallel to the inner walls of the Sciara del Fuoco (SdF) sector collapse depression. The formation of these vents was soon followed by rapid subsidence of the summit crater area. This partly obstructed the central conduit, temporarily choking the fissure and increasing the deformation of the upper part of SdF. The reactivation of the NNW–SSE vent and the opening of a new vent located at 500 m asl, fed by a second dike, released the internal pressure and surface deformation ceased. The eruption then continued again from the 400 m vent, after a summit explosion on 15 March, until ending in early April after a progressive decrease of magma output. Repeated NE–SW dike intrusions have occurred in recent years, close to the upper SE limit of the SdF. In that zone, named Bastimento, the eruptive fractures traced the discontinuities that borders the SdF, increasing the risk of triggering new sector collapse. Whereas the NE–SW trending structures lie along the regional volcanostructural trend of the Aeolian arc through Stromboli, the NNW–SSE vents are oblique to this trend and may be controlled by the anomalous stress field within the unstable flank of the SdF. Another fundamental aspect of the 2007 eruption is the collapse of the central conduit, due to the rapid and deep magma drainage linked to the opening of the 400 m vent. The intrusion of dikes and development of flank vents during the 2007 eruption could possibly have triggered catastrophic landslides and related tsunami or eruptive paroxysms, but the opening of new effusive vents released the internal pressures, diminishing the hazard.
    Beschreibung: In press
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 3.2. Tettonica attiva
    Beschreibung: 3.5. Geologia e storia dei sistemi vulcanici
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: 4.3. TTC - Scenari di pericolosità vulcanica
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): 2007 Stromboli eruption ; Dike-fed vent ; Volcano-Tectonics ; Conduit collapse ; Flank instability ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.08. Volcanic arcs ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.08. Risk::05.08.99. General or miscellaneous
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 51
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    Comparison between different methodologies for detecting Radon in soil along an active fault: the case of the Pernicana fault system, Mt. Etna (Italy) (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Three different methodologies were used to measure Radon (222Rn) in soil, based on both passive and active detection system. The first technique consisted of Solid State Nuclear Track Detectors (SSNTD), CR-39 type, and allowed integrated measurements. The second one consisted of a portable device for short time measurements. The last consisted of a continuous measurement device for extended monitoring, placed in selected sites. Soil 222Rn activity was measured together with soil Thoron (220Rn) and soil carbon dioxide (CO2) efflux, and it was compared with the content of radionuclides in the rocks. Two different soil gas horizontal transects were investigated across the Pernicana fault system (NE flank of Mount Etna), from November 2006 to April 2007. The results obtained with the three methodologies are in a general agreement with each other and reflect the tectonic settings of the investigated study area. The lowest 222Rn values were recorded just on the fault plane, and relatively higher values were recorded a few tens of meters from the fault axis on both of its sides. This pattern could be explained as a dilution effect resulting from high rates of soil CO2 efflux. Time variations of 222Rn activity were mostly linked to atmospheric influences, whereas no significant correlation with the volcanic activity was observed. In order to further investigate regional radon distributions, spot measurements were made to identify sites having high Rn emissions that could subsequently be monitored for temporal radon variations.. SSNTD measurements allow for extended-duration monitoring of a relatively large number of sites, although with some loss of temporal resolution due to their long integration time. Continuous monitoring probes are optimal for detailed time monitoring, but because of their expense, they can best be used to complement the information acquired with SSNTD in a network of monitored sites.
    Beschreibung: In press
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 3.2. Tettonica attiva
    Beschreibung: 4.4. Scenari e mitigazione del rischio ambientale
    Beschreibung: 4.5. Degassamento naturale
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Soil Radon and Thoron activity ; soil CO2 efflux ; Pernicana fault system ; Mount Etna ; volcano-tectonic monitoring ; 03. Hydrosphere::03.04. Chemical and biological::03.04.07. Radioactivity and isotopes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.08. Instruments and techniques ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.02. Exploration geophysics::04.02.05. Downhole, radioactivity, remote sensing, and other methods ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 52
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    An exceptional case of endogenous lava dome growth (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: During an eruption at the Bocca Nuova, one of the summit craters of Mt. Etna, in October-November 1999 a part of the crater floor near its WNW rim was uplifted to form a dome-shaped feature that consisted of older lava and pyroclastics filling the crater. This endogenous dome grew rapidly over the crater rim, thus being perched precariously over the steep outer slope of the Bocca Nuova, and near-continuous collapse of its steep flanks generated swiftly moving pyroclastic avalanches over a period of several hours. These avalanches advanced at speeds of 10-20 m s-1 and extended up to 0.7 km from their source on top of lavas emplaced immediately before. Their deposits were subsequently covered by lava flows that issued from vents below the front of the dome and from the Bocca Nuova itself. Growth of the dome was caused by the vertical intrusion of magma in the marginal W part of the crater, which deformed and uplifted previously emplaced, still hot and plastically deformable eruptive products filling the crater. The resulting avalanches had all characteristics of pyroclastic flows spawned by collapse of unstable flanks of lava domes, but in this case the magma involved was of mafic (hawaiitic) composition and would have, under normal circumstances, produced fluid lava flows. The formation of the dome and the generation of the pyroclastic avalanches owe their occurrence to the rheological properties of the eruptive products filling the crater, which were transformed into the dome, and to the morphological configuration of the Bocca Nuova and its surroundings. The density contrast between successive erupted products may also have played a role. Although events of this type are to be considered exceptional at Etna, their recurrence might represent a serious hazard to visitors to the summit area.
    Beschreibung: Published
    Beschreibung: 115-128
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Mt. Etna ; Bocca Nuova ; endogenous lava dome ; pyroclastic avalanches ; magma ascent ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions ; 05. General::05.08. Risk::05.08.99. General or miscellaneous
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 53
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    Modeling the interplay of fO2 and fS2 along the FeS-silicate melt equilibrium (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: In this paper we will discuss a simplified thermodynamic description for the saturation of FeS, either liquid or solid, in magmatic melts. The Conjugated-Toop–Samis–Flood–Grjotheim model [Moretti R. and Ottonello G., 2005. Solubility and speciation of sulfur in silicate melts, the Conjugated-Toop–Samis–Flood–Grjotheim (CTSFG) model. Geochimica et Cosmochimica Acta, 69, 801–823] has furnished the theoretical reference frame, since it already accounts for the solubility of gaseous sulfur and the speciation and oxidation state of sulfur in silicate melts. We provide a new model to predict the saturation of magmatic silicate melts with an FeS phase that is internally consistent with these previous parameterizations. The derived model provides an effective sulfogeobarometer, which is superior with respect to previous models. For magmas rising from depth to surface, our appraisal of molar volumes of sulfur-bearing species in silicate melts allows us to model oxidation–reduction processes at different pressures, and sulfur concentrations for saturationwith either liquid or solid phases. In this respect, the nature of the oxygen fugacity buffer is critical. On the basis of model results on some typical compositions of volcanological interest, the sulfur contents at sulfide saturation (SCSS) have been calculated and the results duplicate the experimental observations that the SCSS is positively correlatedwith pressure forwatersaturated acidic melts and negatively correlated with pressure for water-poor basaltic melts. This new model provides fO2–fS2 pairs of FeS saturation of natural silicatemelts. In caseswhere the redox constraint is lacking, the model can be used to investigate whether the dissolved sulfur content approaches SCSS or not, and if so, to estimate at which fO2 value the silicate melt is saturated with a sulfide phase
    Beschreibung: Published
    Beschreibung: 286–298
    Beschreibung: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Sulfur ; Silicate melt ; Iron sulfide ; Chemical thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 54
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    Emplacement mechanism of gravity flows inferred fromhigh resolution Lidar data: The 1944 Somma–Vesuvius lava flow (Italy) (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: A Digital Terrain Model derived from high resolution Lidar data allows the determination of the morphometric and physical parameters of a lava flow erupted from the Somma–Vesuvius volcano in 1944. The downstream variation of morphometric parameters including slope, aspect, relative relief, thickness, width, and cross sectional area is analyzed, and the changes in viscosity, velocity and flow rate are estimated. The aims of the analyses are to recognize different flow surfaces, to reconstruct the flow kinematics, and to obtain information on the mechanism of emplacement. The results indicate that the 1944 lava flow can be divided in three sectors: a near vent sector (NVS) characterized by a toe-like surface, an intermediate sector (IS) with an ‘a’ātype brittle surface, and a distal sector (DS) with a sheet-like ductile surface. Lateral leveés and channels do not occur in NVS, whereas they are well developed in IS. In DS, leveés increase with an increasing distance from the vent. Fold-like surfaces occur in NVS and DS, reflecting local shortening processes due to a decrease in the slope of the substratum and overflows from the main channel. IS and DS emplaced between March 18 and 21, 1944, whereas NVS emplaced on March 19 and partly covered IS. The morphometric and physical parameters indicate that IS moved in a ‘tube’-like regime, whereas DS emplaced in a 'mobile crust' regime. The IS to DS transition is marked by an increase in velocity and the flow rate, and by a decrease in thickness, width, cross sectional area, and viscosity. This transition is due to an abrupt increase in the slope of the substratum. The estimated velocity values are in good agreement with the measurements during the 1944 eruption. The analysis used here may be extended to other lava flows. Some gravity flows (debris/mud flows, floods, and avalanches) have rheological properties and shapes similar to those of lavas, and the same process-form relationships may apply to these flows. The approach used here may be therefore useful for evaluating hazards from various gravity currents.
    Beschreibung: Published
    Beschreibung: 223–235
    Beschreibung: 1.10. TTC - Telerilevamento
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: 5.4. TTC - Sistema Informativo Territoriale
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Lava flow ; Gravity flow ; Lidar ; Digital Terrain Model (DTM) ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 55
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    Effects of soil gas permeability and recirculation flux on soil CO2 flux measurements performed using a closed dynamic accumulation chamber (2009)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Dynamic accumulation chamber methods have been extensively used to estimate the total output of CO2 released from active volcanic area. In order to asses the performance and reliability of a closed dynamic system several tests were carried out with different soil permeabilities and soil CO2 fluxes. A special device was used to create a constant one-dimensional CO2 flux through a soil column with a known permeability. Three permeabilities were investigated, ranging between 3.6 × 10− 2 and 3.5 × 10 μm2, as were several CO2 fluxes (ranging between 1.1 × 10− 6 and 6.3 × 10− 5 kg m− 2 s− 1). The results highlight that the accuracy of soil CO2 flux measurements strictly depends on the soil gas permeability and the soil CO2 flux regimen. Generally chamber measurements underestimate CO2 fluxes at low soil permeability and low soil CO2 fluxes, whereas appreciable overestimations occur for high permeability soil, especially for high soil CO2 fluxes. Other tests carried out with different settings for the measurement device, such as the chamber volume and the flux of the pump used to recirculate air through the chamber and the gas analyzer (recirculation flux), revealed a strong dependence of the closed dynamic chamber measurements on the recirculation flux. Low recirculation fluxes (0.2–0.4 l min− 1) decreased the performance of the measurement system, causing underestimations of the actual soil CO2 flux, whereas higher values (0.6–1.0 l min− 1) resulted in overestimations, especially for elevated soil CO2 fluxes. An empirical equation was deduced to allow accumulation chamber fluxes to be calculated very accurately based on soil gas permeabilities measured in the field.
    Beschreibung: Published
    Beschreibung: 387-393
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Soil CO2 flux measuraments ; Closed dynamic chamber ; soil gas permeability ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 56
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    Time-dependent deformation of the eastern flank of Mt. Etna: after-slip or viscoelastic relaxation? (2009)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Major results of post-intrusive GPS monitoring of the five months encompassing and following the onset of 2002-03 Mt. Etna eruption are presented and discussed here. The overall ground deformation pattern is characterized by a time-dependent relaxation function. We evaluated two different parameterizations of relaxation functions, each one linked to a different relaxation process: i) viscoelastic relaxation and ii) after-slip mechanism. The former indicated that the process occurred within a weak layer characterized by viscosity values ranging between 7.1 • 1014 Pa s and 1.3 • 1015 Pa s. The latter evidenced that frictional processes occurred beneath a layer of velocity-strengthening having a thickness with values ranging between 0.4 km and 1.7 km. Either model may explain the observed time-dependent deformation, both from the statistical point of view and the comparison with geologic and seismic information. Although we are unable to favour one model rather than the other, these results indicate that the mechanism, responsible for the observed post-intrusive deformation, occurs within a sliding “zone” located inside the clayey sedimentary basement.
    Beschreibung: This study was undertaken with financial support from the FLANK project (DPC-INGV 2008 - 2010 contract)
    Beschreibung: Published
    Beschreibung: 300-311
    Beschreibung: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): 2002-03 Mt. Etna eruption ; Post-intrusive relaxation ; Viscoelastic ; After-slip ; Rheology ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 57
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    Fingerprinting ash deposits of small scale eruptions by their physical and textural features (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Correlation of distal ash deposits with their proximal counterparts mainly relies on chemical and mineralogical characterization of bulk rock and matrix glasses. However, the study of juvenile fragments often reveals the heterogeneity in terms of clast shape, external surface, groundmass texture and composition. This is particularly evident in small scale eruptions, characterized by a strong variability in texture and relative abundance of juvenile fragments. This heterogeneity introduces an inherent uncertainty, that makes the compositional data alone inadequate to unequivocally characterize the tephra bed. Pyroclast characteristics, if described and quantified, can represent an additional clue for the correct identification of the tephra. The paper presents morphological, textural and compositional data on the products of an ash eruption from Middle Age activity of Vesuvius, to demonstrate the information that can be extracted from the proposed type of analysis. Juvenile fragments from five ash layers throughout the studied products were randomly hand-picked and fully characterized in terms of external morphology, particle outline parameterization, groundmass texture and glass composition. Statistical analysis of shape parameters characterized groups of fragments that can be compared with the other textural and physical parameters. The main result is that the data do not show important cross-correlation so suggesting that all of these parameters, together with accurate field data are needed for the complete fingerprinting of a tephra bed. We suggest that this approach is especially important for characterizing the products of small scale, compositionally undistinguishable, eruptions and represents the necessary step to deal with before going into more detailed compositional analyses.
    Beschreibung: Published
    Beschreibung: 277-287
    Beschreibung: 3.5. Geologia e storia dei sistemi vulcanici
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): tephrostratigraphic methods ; shape parameters ; groundmass texture ; mid-intensity eruptions ; ash deposits ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 58
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    Deep water gravity core from the Marsili Basin (Tyrrhenian Sea) records Pleistocenic–Holocenic explosive events and instability of the Aeolian Archipelago (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: A 4.8 m long gravity core was recovered on a relative topographic high in the northern part of the Marsili Basin (southern Tyrrhenian Sea) at a water depth of 3200 m. The core was taken in order to decipher the sedimentary record of the past volcanic events of the nearby Aeolian arc. A succession of thin (2 cm to 5 cm thick) fine-grained turbidites, mainly of volcaniclastic origin, topped by hemipelagic mud layers and a number of primary tephra layers were recovered by the core. The most prominent turbidite occurs in the lower part of the core at 385 cm. It consists of a 20 cm-thick, thinning-upward, pebble to sand-sized bed. Grain-size analysis and component compositions in the 0.063–0.250 mm size fractions were determined on thirty samples taken from primary tephra beds and the silty–sandy basal part of the volcaniclastic turbidite units. SEM scans and glass fraction chemical analyses were successively carried out on a selection of 17 samples. To aid source correlation and comparison, sub-aerial tephras of the Lower Pollara (Salina, 24 ± 3.6 ka), Gabellotto-Fiumebianco (Lipari, 8.5 or 11.5 ka), Monte Pilato (Lipari, 749 or 580 AD) and Secche di Lazzaro (Stromboli, ~ 5 ka) eruptions were also analyzed with the same procedure. Primary tephra respectively belonging to the eruptions of Lower Pollara, Gabellotto-Fiumebianco and Vesuvius (AP eruptions 3.5 ka–79 AD) were identified in the core at the expected relative stratigraphic depths. Two turbidite beds composed of monogenic glass shards were also identified and interpreted as the remobilisation of primary tephras of Secche di Lazzaro (Stromboli, 5 ka) and Pilato (Lipari, 580 or 749 AD). Tephrochronology results indicate that the cored sequence formed in the last 30 ka suggesting an average sedimentation rate of 0.15–0.17 mm/y. The thick pebbly sandy turbidite unit in the lower part of the core has component and glass composition compatible with the Lower Pollara volcanic sequence of Salina Island. In view of the grain-size and thickness of the turbidite unit, we suggest that it represents the deposit of a large failure event. The tephra corresponding to the Lower Pollara event lies below the turbidite unit, separated by 16 cm of hemipelagic mud, indicating that the collapse took place sometime after the eruption.
    Beschreibung: Published
    Beschreibung: 133-144
    Beschreibung: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Beschreibung: 3.5. Geologia e storia dei sistemi vulcanici
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): tephrochronology ; turbidity current ; flank collapse ; Marsili Basin ; gravity core ; 04. Solid Earth::04.04. Geology::04.04.04. Marine geology ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
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  • 59
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    Recicling and “re-hydration” of degassed magma inducing transient dissolution/crystallization events at Stromboli (Italy) (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Intrusive degassing and recycling of degassed and dense magma at depth have been proposed for a long time at Stromboli. The brief explosive event that occurred at the summit craters on 9 January 2005 threw out bombs and lapilli that could be good candidates to illustrate recycling of shallow degassed magma at depth. We present an extensive data set on both the textures and the mineral, bulk rock and glassy matrix chemistry of the “9 Jan” products. The latter have the common shoshonitic–basaltic bulk composition of lavas and scoriae issued from typical strombolian activity. In contrast they differ by the heterogeneous chemistry of their matrix glasses and their crystal textures that testify to crystal dissolution event(s) just prior magma crystallization upon ascent and eruption. Comparison between mineral paragenesis of the natural products and experimental phase equilibria suggest water-induced magma re-equilibration. We propose that mineral dissolution is related to water enrichment of the recycled degassed magma, via differential gas bubble transfer and to some extents its physical mixing with volatile-rich magma blobs. However, all these features illustrate transient processes. Even though evidence of mineral dissolution is ubiquitous at Stromboli, its effect on the bulk magma chemistry is minor because of the subtle interplay between mineral dissolution and crystallization in magmas having comparable bulk chemistry.
    Beschreibung: Published
    Beschreibung: 325-336
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): mineral dissolution ; magma chemistry ; volatiles ; trace elements ; Stromboli ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 60
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    Diffuse degassing of carbon dioxide at Somma-Vesuvius volcanic complex (Southern Italy) and its relation with regional tectonics (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: A systematic survey of soil CO2 concentrations was carried out on the flanks of Somma^Vesuvius volcano in order to constrain possible pathways responsible of carbon dioxide diffuse degassing taking place during the present state of quiescence. Measurements were performed at 1162 sites in late winter^spring 2000,highlighting that soil CO2 concentrations range from 50 to 10500 ppmV. A statistical analysis was developed in order to define the threshold value of anomaly and separate the biogenic CO2 component,produced by soil respiration,from the inorganic component of deep provenance. A computer routine was also elaborated to interpret the grid of CO2 anomalous concentration values and define the actual location,orientation and length of degassing structures. The results obtained by this procedure reveal a main control of the regional stress field on the patterns of gas migration. The identified degassing lineaments are typically oriented along the Apenninic (NW^SE) and anti-Apenninic (NE^SW)trends,which are known to govern the past geological and structural evolution of the Campanian Plain and present seismicity and deformation pattern of Mount Vesuvius. A main degassing area was recognized on the eastern and southern flanks of the volcano,which likely relates to the geometry of the underlying carbonate basement,reaching its top (500 m depth) in this sector of the volcano.
    Beschreibung: Published
    Beschreibung: 55-79
    Beschreibung: partially_open
    Schlagwort(e): Somma-Vesuvius ; CO2 degassing ; Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 61
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    Birth, growth and morphologic evolution of the `Laghetto´ cinder cone during the 2001 Etna eruption (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: We have undertaken detailed observations of the formation of the `Laghetto´ cinder cone, a new cone that formed during a 2-week period of intense activity in Piano del Lago, on the upper slopes of Mount Etna in summer 2001. We describe the events leading to the formation of a small graben, the formation of pit craters on the base of the graben, the onset of phreatomagmatic activity, a transition to intense Strombolian activity, and a return to phreatomagmatic activity as the eruption came to an end. We discuss the reasons for these transitions, and describe the morphological development of the cone during these events. Arcuate cracks on the southern part of the cone were related to withdrawal of magma at the end of the eruption. Other slope instabilities that developed during the eruption include the formation of small radial grain flows on the outer flanks of the cone and the collapse into the crater of part of the crater rim. Some of the failure planes we observed were first identified using a FLIR TM 695 thermal infrared camera. This is the first time that infrared thermography has been used to detect instability of volcanic structures. Results obtained during this test case demonstrate that thermal cameras are a very useful tool for studies of volcanic instability.
    Beschreibung: Published
    Beschreibung: 225-239
    Beschreibung: partially_open
    Schlagwort(e): Etna volcano ; cinder cone ; volcano instability ; thermal images ; phreatomagmatic activity ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 62
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    The buried caldera of Misti volcano, Peru, revealed by combining a self-potential survey with elliptic Fourier function analysis of topography (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: This survey proposes a new approach to identify buried caldera boundaries of a volcanic cone, combining (1) a systematic elliptic Fourier functions (EFF) analysis on the contour lines based on the external shape of the edifice with (2) self-potential (SP) measurements on volcano flanks. The methodology of this approach is to investigate the relationships between (1) vertical morphological changes inferred from EFF analysis and (2) lateral lithological transition inside the edifice inferred from SP/elevation gradients. The application of these methods on Misti volcano in southern Peru displays a very good correlation. The three main boundaries evidenced by hierarchical cluster analysis on the contour lines coincide with the two main boundaries characterised by SP signal and with a secondary SP signature related with a summit caldera. In order to explain these results showing a very good correlation between morphologic and lithologic changes as function of elevation, caldera boundaries have been suggested. The latter would be located at an average elevation of (1) 4350–4400 m, (2) 4950–5000 m, and (3) 5500– 5550 m. For the lowest boundary in elevation, the coincidence with the lateral extension of the hydrothermal system inferred from SP measurements suggests that caldera walls act as a barrier for lateral extension of hydrothermal systems. In the summit area, the highest boundary has been related with the summit caldera, inferred by a secondary SP minimum and geological evidence.
    Beschreibung: - Institut de Recherche pour le Développement (IRD) - Instituto Geofisico del Peru´ (IGP).
    Beschreibung: Published
    Beschreibung: 283– 297
    Beschreibung: partially_open
    Schlagwort(e): caldera ; elliptic Fourier functions ; geomorphology ; self-potential ; Misti volcano ; Peru ; 03. Hydrosphere::03.02. Hydrology::03.02.02. Hydrological processes: interaction, transport, dynamics ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.02. Exploration geophysics::04.02.04. Magnetic and electrical methods ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 05. General::05.02. Data dissemination::05.02.04. Hydrogeological data ; 05. General::05.05. Mathematical geophysics::05.05.99. General or miscellaneous ; 05. General::05.08. Risk::05.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 63
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    2001 flank eruption of the alkali- and volatile-rich primitive basalt responsible for Mount Etna's evolution in the last three decades (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Since the early 1970s enhanced eruptive activity of Mount Etna has been accompanied by selective geochemical changes in erupted lavas, among which a gradual increase of alkalis whose origin is still debated. Here we provide further insight into the origin of this recent evolution, based on a detailed study of the chemistry and dissolved volatile content of melt inclusions trapped in olivine crystals of unusual plagioclase-poor primitive basalt that was extruded during a highly explosive flank eruption in July–August 2001. Two types of lava were erupted simultaneously along a N–S fracture system. Trachybasalts from the upper vents (2950–2700 m) were simply drained out by fracturing of the central volcanic conduit. They are identical to summit crater lavas and contain Mg-poor olivines (Fo70–72) with evolved and volatile-poor melt inclusions that represent late-stage crystallisation during shallow open conduit degassing. In contrast, plagioclase-poor basalt (80% of total) extruded through the lower vents (2550–2100 m) derived from lateral dyke intrusion of a more primitive and volatile-rich magma across the sedimentary basement. This primitive melt is best preserved in rare Fo82.4–80.5 skeletal olivines present in lapilli deposits from the most powerful activities at the 2550 m vent. Its high dissolved contents of H2 O (3.4 wt.%), CO2 (0.11 to 0.41 wt.%), S (0.32 wt.%), Cl (0.16 wt.%) and F (0.094 wt.%) point to its closed system ascent from ∼400 to 250 MPa (∼12 to 6.5 km depth b.s.l.). However, the predominance of euhedral olivine phenocrysts with common reverse zoning (cores Fo76–78 and rims Fo78–80) and decrepited inclusions shows that most of the erupted basalt derived from a slightly more evolved, crystallizing body of the same magma that was invaded by the uprising primitive melt prior to erupting. The few preserved inclusions in these olivines indicate pre-eruptive storage of that magma body at about 5 km depth b.s.l., in coherence with seismic data. We propose that the 2001 flank eruption resulted from gradual overpressuring of Etna's shallow plumbing system due to the influx of volatile-rich primitive basalt that may have begun several months in advance. We find that this basalt is much richer in alkalis (2.0 wt.% K2 O) and has higher S/Cl (2.0) but lower Cl/K and Cl/F ratios than all pre-1970s Etnean lavas (1.4 wt.% K2 O, S/Cl=1.5), as further exemplified by melt inclusions in entrained olivine xenocrysts. Combining these new observations with previously published data, we argue that the 2001 basalt represents a new alkali-rich basic end-member feeding Mt. Etna, only few amount of which had previously been extruded during a 1974 peripheral eruption and, more recently, during brief paroxysmal summit events. Over the last three decades this new magma has progressively mixed with and replaced the former K-poorer trachybasalts filling the plumbing system, leading to extrusion of gradually more primitive and alkali-richer lavas. Its geochemical singularities cannot result from shallow crustal contaminations. Instead, they suggest the involvement of an alkali-richer but Cl-poorer arc-type component during recent magma genesis beneath Etna.
    Beschreibung: Published
    Beschreibung: 1-17
    Beschreibung: partially_open
    Schlagwort(e): Mt. Etna ; volatiles ; degassing ; eruptive mechanism ; magma geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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  • 64
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    Development of tumuli in the medial portion of the 1983 aa flow-field, Mount Etna, Sicily (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: A number of tumuli formed on the aa-dominated lava fan complex which developed in the medial zone of the 1983 flow-field of Mount Etna during the later stages of the eruption. This complex flow-field formed on shallow sloping ground below a scarp between 1900 and 1700 m asl. A major tube system fed a branching tube network in the fan complex. Numerous tumuli and break-outs of lava formed in the fan. Three main types of tumulus are identified: (1) Focal tumuli, which are formed from the break-up and uplift of `old´, thick lava crust and themselves become sustained sites for the distribution of lava both as flows and within distributary tubes. These focal tumuli are significant centres associated with major tubes. (2) Satellite tumuli, which are typically elongate, whale-back shaped features that branch out from focal tumuli. These satellite tumuli were initially lava flows erupted from a focal tumulus. The crust of the flow slowed or came to a halt and the rigid crust became uplifted and fractured, forming a dome-shaped ridge feature. These satellite tumuli continued to be fed from the focal tumulus and became sites of lava emission with numerous break-outs. (3) Distributary tumuli formed on the fan associated with short-lived break-outs from tubes and are relatively simple structures formed from limited effusion of toey lobes and pahoehoe lava. The major tumuli on the fan complex show distinct dilation fractures. The fracture surfaces provide good exposure of the crust and three distinct zones are recognised – an upper zone showing columnar jointing, a middle zone consisting of planar fracture surfaces and a basal zone with distinctive banded planar fracture surfaces showing evidence of both brittle and ductile formation. Using these data a model is proposed for tumulus growth. Field analysis of the fan complex shows how it was fed by a branching tube system, leading to flow thickening, formation of tumuli and numerous ephemeral boccas.
    Beschreibung: Published
    Beschreibung: partially_open
    Schlagwort(e): aa lava flow-field ; Mount Etna ; tumulus ; lava crust and lava tubes. ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 65
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    Genesis of chlorine and sulphur in fumarolic emissions at Vulcano Island (Italy) : assessment of pH and redox conditions in the hydrothermal system (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Chlorine- and sulphur-bearing compounds in fumarole discharges of the La Fossa crater at Vulcano Island (Italy) can be modelled by a mixing process between magmatic gases and vapour from a boiling hydrothermal system. This allows estimating the compounds in both endmembers. Magma degassing cannot explain the time variation of sulphur and HCl concentrations in the deep endmember, which are more probably linked to reactions of solid phases at depth, before mixing with the hydrothermal vapours. Based on the P^T conditions and speciation of the boiling hydrothermal system below La Fossa, the HCl and Stot contents in the hydrothermal vapours were used to compute the redox conditions and pH of the aqueous solution. The results suggest that the haematite magnetite buffer controls the hydrothermal fO2 values, while the pH has increased since the end of the 1970s. The main processes affecting pH values may be linked to Na^Ca exchanges between evolved seawater, feeding the boiling hydrothermal system, and local rocks. While Na is removed from water, calcium enters the solution, undergoes hydrolysis and produces HCl,lowering the pH of the water. The increasing water^rock ratio within the hydrothermal system lowers the Ca availability, so the aqueous solution becomes less acidic. Seawater flowing towards the boiling hydrothermal brine dissolves a large quantity of pyrite along its path. In the boiling hydrothermal system, dissolved sulphur precipitates as pyrite and anhydrite, and becomes partitioned in vapour phase as H2S and SO2. These results are in agreement with the paragenesis of hydrothermal alteration minerals recovered in drilled wells at Vulcano and are also in agreement with the isotopic composition of sulphur emitted by the crater fumaroles.
    Beschreibung: Published
    Beschreibung: 137-150
    Beschreibung: partially_open
    Schlagwort(e): chlorine ; sulphur ; hydrothermal system ; genetic processes ; Vulcano Island ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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  • 66
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    Contrasting triggering mechanisms of the 2001 and 2002–2003 eruptions of Mount Etna (Italy) (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Mount Etna produced two significant eruptions in 2001 and 2002–2003, which we have analysed using geological, seismic and deformation data. These eruptions showed some similarities, such as the activating of two magmatic plumbing systems (central–lateral and eccentric), but they differed in their triggering mechanisms. While the 2001 eruption was largely the result of the emplacement of a N–S eccentric dike (independent from the central conduits) consistent with E–W regional extension, the 2002–2003 eruption occurred in response to a major flank slip on the eastern and southeastern sides of the volcano. This is demonstrated by the spatial and temporal distribution of seismicity and deformation preceding and accompanying the two eruptions. During the months prior to the 2001 eruption, most epicenters were concentrated on the southern flank, at depths of 5–15 km below sea level. During the 4 days before the eruption, earthquake hypocenters migrated to shallower levels (from 5 km bsl. upward) indicating the emplacement of the eccentric dike. This is confirmed by the patterns of ground fracturing observed in the field and deformation documented by electronic distance measurements (EDM). In contrast, the months before the 2002–2003 eruption were characterised by shallower seismicity, mainly concentrated along the active faults bordering the slipping flank sector. Flank slip accelerated in September 2002 and a second, more vigorous acceleration of flank slip occurred on 26–27 October 2002, accompanying the opening of eruptive vents. The very short (2 h) seismic crisis preceding the onset of eruptive activity stands in neat contrast with the 4 days of intense seismicity before the 2001 eruption. Subsequently, flank slip-deformation extended all over the eastern and southeastern flanks of the volcano, causing serious damage in this sector. The events of 2001–2003 can be seen as a continuous chain of intimately interacting processes including regional tectonics, magma accumulation and eruption, and flank instability. In this scenario the 2001 eruption led to increased flank instability that subsequently accelerated and culminated with the massive flank slip, which in turn facilitated the 2002–2003 eruption. This sequence of events points to a long-term feedback mechanism between magmatism and flank instability at Etna.
    Beschreibung: Published
    Beschreibung: 235-255
    Beschreibung: partially_open
    Schlagwort(e): eruption triggering ; central–lateral vs. eccentric eruptions ; flank instability and slip ; volcano-tectonics ; Mt. Etna ; instrumental monitoring ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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    Fluid circulation at Stromboli volcano (Aeolian Islands, Italy) from self-potential and CO2 surveys (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: This work addresses the study of fluid circulation of the Stromboli island using a dense coverage of self-potential (SP) and soil CO2 data. A marked difference exists between the northern flank and the other flanks of the island. The northern flank exhibits (1) a typical negative SP/altitude gradient not observed on the other flanks, and (2) higher levels of CO2. The general SP pattern suggests that the northern flank is composed of porous layers through which vadose water flows down to a basal water table, in contrast to the other flanks where impermeable layers impede the vertical flow of vadose water. In the Sciara del Fuoco and Rina Grande-Le Schicciole landslide complexes, breccias of shallow gliding planes may constitute such impermeable layers whereas elsewhere, poorly permeable, fine-grained pyroclastites or altered lava flows may be present. This general model of the flanks also explains the main CO2 patterns: concentration of CO2 at the surface is high on the porous north flank and lower on the other flanks where impermeable layers can block the upward CO2 flux. The active upper part of the island is underlain by a well-defined hydrothermal system bounded by short-wavelength negative SP anomalies and high peaks of CO2. These boundaries coincide with faults limiting ancient collapses of calderas, craters and flank landslides. The hydrothermal system is not homogeneous but composed of three main subsystems and of a fourth minor one and is not centered on the active craters. The latter are located near its border. This divergence between the location of the active craters and the extent of the hydrothermal system suggests that the internal heat sources may not be limited to sources below the active craters. If the heat source strictly corresponds to intrusions at depth around the active conduits, the geometry of the hydrothermal subsystems must be strongly controlled by heterogeneities within the edifice such as craters, caldera walls or gliding planes of flank collapse, as suggested by the correspondence between SP^CO2 anomalies and structural limits. The inner zone of the hydrothermal subsystems is characterized by positive SP anomalies, indicating upward movements of fluids, and by very low values of CO2 emanation. This pattern suggests that the hydrothermal zone becomes self-sealed at depth, thus creating a barrier to the CO2 flux. In this hypothesis, the observed hydrothermal system is a shallow one and it involves mostly convection of infiltrated meteoric water above the sealed zone. Finally, on the base of CO2 degassing measurements, we present evidence for the presence of two regional faults, oriented N41‡ and N64‡, and decoupled from the volcanic structures.
    Beschreibung: Published
    Beschreibung: 1^18
    Beschreibung: partially_open
    Schlagwort(e): Stromboli ; hydrothermal system ; self-potential ; soil gas ; carbon dioxide ; Aeolian islands ; 03. Hydrosphere::03.02. Hydrology::03.02.02. Hydrological processes: interaction, transport, dynamics ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 68
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    Geochemistry of fluids from submarine hot springs at Punta de Mita, Nayarit, Mexico (2006)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Thermal springs with a maximum measured temperature of 89°C discharge hot water and gas from a depth of 11 m, 400 m offshore of Punta Pantoque, located in the northern part of Bahìa de Banderas, near Puerto Vallarta, Mexico. The composition of all water samples collected from the sea bottom is close to that of sea water. Nevertheless, it was possible to estimate the thermal endmember composition by extrapolating the sulfate concentration to zero. This endmember is similar in chemical composition both to waters of the Rio Purificacion and La Tuna thermal springs, located to the South along the Pacific coast of the Jalisco Block, and to pore waters from the deep-sea drilling cores from some accretionary complexes. Gas composition as well as isotopic composition of He and carbon from CO2, CH4 and C2H6 suggests an essentially thermo-biogenic origin for the gas and the presence of a high proportion of radiogenic, crustal helium. Isotopic composition of He in the Punta de Mita gas (0.4 Ra) is the lowest ever measured in Mexican hydrothermal gases. These findings do not support the idea that there exists a direct connection between the Punta de Mita springs and the last volcanic events which occurred in this area at V3 Ma. Rather, this hydrothermal activity is related to deep active faulting and the existence of a deep regional aquifer or local aquifers of connate waters underlying the granites of the Jalisco Block.
    Beschreibung: Published
    Beschreibung: 329-338
    Beschreibung: partially_open
    Schlagwort(e): submarine springs ; hydrothermal systems ; geothermometry ; He-isotopes ; formation waters ; Jalisco Block ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 69
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    The Magma feeding system of Somma-Vesuvius (Italy)strato-volcano:new inferences from a review of geochemical and Sr,Nd,Pb and O isotope data. Volcanism in the Campania Plain: Vesuvius, Campi Flegrei and Ignimbrites (2007)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: A large database of major, trace and isotope (Sr, Nd, Pb, O) data exists for rocks produced by the volcanic activity of Somma-Vesuvius volcano. Variation diagrams strongly suggest a major role for evolutionary processes such as fractional crystallization, contamination, crystal trapping and magma mixing, occurring after magma genesis in the mantle. Most mafic magmas are enriched in LILE (K, Rb, Ba), REE (Ce, Sm) and Y, show small Nb–Ta negative anomalies, and have values of Nb/Zr at about 0.15. Enrichments in LILE, REE, Nb and Ta do not correlate with Sr isotope values or degree of both K enrichment and silica undersaturation. The results indicate mantle source heterogeneity produced by slab-derived components beneath the volcano. However, the Sr isotope values of Somma-Vesuvius increase from 0.7071 up to 0.7081 with transport through the uppermost 11–12 km of the crust. The Sr isotope variation suggests that the crustal component affected the magmas during ascent through the lithosphere to the surface. Our new geochemical assessment based on chemical, isotopic and fluid inclusion data points to the existence of three main levels of magma storage. Two of the levels are deep and may represent long-lived reservoirs, and an uppermost crustal level that probably coincides with the volcanic conduit. The deeper level of magma storage is deeper than 12 km and fed the 1944 AD eruption. The intermediate level coincides with the seismic discontinuity detected by Zollo et al. (1996) at about 8 km. This intermediate level supplies magmas with 87Sr/86Sr values between 0.7071 and 0.7074, and δO18 8‰ that typically erupted both during interplinian (i.e. 1906 AD) and sub-plinian (472 AD, 1631 AD) events. The shallowest level of magma storage at about 5 km was the site of magma chambers for the Pompei and Avellino eruptions. New investigations are necessary to verify the proposed magma feeding system.
    Beschreibung: Published
    Beschreibung: 183-204
    Beschreibung: open
    Schlagwort(e): NONE ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: book chapter
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  • 70
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    Time-dependent geochemistry of clinopyroxene from Alban Hills (Central Italy): clues to source and evolution of ultrapotassic magmas. (2007)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: We investigated chemical and isotopic compositions of clinopyroxene crystals from well age-constrained juvenile scoria clasts, lava flows, and hypoabyssal magmatic ejecta representative of the whole eruptive history of the Alban Hills Volcanic District. The Alban Hills is a Quaternary ultra-potassic district that was emplaced into thick limestone units along the Tyrrhenian margin of Italy. Alban Hills volcanic products, even the most differentiated, are characterised by low SiO2 content. We suggest that the low silica activity in evolving magmas can be ultimately due to a decarbonation process occurring at the magma/limestone interface. According to the liquid line of descent we propose, the differentiation process is driven by crystallisation of clinopyroxene+leuciteFapatiteFmagnetite coupled with assimilation of a small amount of calcite and/or with interaction with crustal CO2. By combining age, chemical data, strontium and oxygen isotopic compositions, and REE content of clinopyroxene, we give insights into the evolution of primitive ultrapotassic magmas of the Alban Hills Volcanic District over an elapsed period of about 600 kyr. Geochemical features of clinopyroxene crystals, consistent with data coming from other Italian ultrapotassic magmas, indicate that Alban Hills primary magmas were generated from a metasomatized lithospheric mantle source. In addition, our study shows that the 87Sr / 86Sr and LREE/HREE of Alban Hills magmas continuously diminished during the 600–35 ka time interval of the Alban Hills eruptive history, possibly reflecting the progressive depletion of the metasomatized mantle source of magmas.
    Beschreibung: Published
    Beschreibung: 330–346
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Clinopyroxene ; 87Sr / 86Sr ; REE ; Ultrapotassic rocks ; Alban Hills ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 71
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    Evaluation of carbon isotope fractionation of soil CO2 under an advective–diffusive regimen: A tool for computing the isotopic composition of unfractionated deep source (2007)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: A physical model based on the advective–diffusion theory was developed in order to describe the mixing between a deep gas source and the atmosphere. The model was used to predict the isotopic fractionation of carbon in soil CO2. Gas samples were collected at different depths in areas characterized by different geological settings and CO2 fluxes. The relative theoretical and experimental isotopic profiles were compared and a good agreement was found. These profiles show how the isotopic composition of CO2 changes through the upper few decimeters of soil and how the amount of the isotopic fractionation is strongly influenced by soil CO2 flux. Finally, the model was used to derive the carbon isotopic composition of unfractioned deep CO2 source for all the investigated sites
    Beschreibung: Published
    Beschreibung: 3016–3027
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: 2.4. TTC - Laboratori di geochimica dei fluidi
    Beschreibung: 4.5. Degassamento naturale
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Carbon isotope fractionation ; soil degassing ; gas transport ; D13C(CO2) ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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    Mapping the Moho of the Western Alps by wide-angle reflection seismics (2007)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: In the text
    Beschreibung: Published
    Beschreibung: 193-202
    Beschreibung: 3.3. Geodinamica e struttura dell'interno della Terra
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): CROP ; wide-angle ; reflection ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 73
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    Magma-carbonate interaction: an experimental study on ultrapotassic rocks (2007)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: The Alban Hills ultrapotassic volcanic district is one of the main districts emplaced during Quaternary time along the Tyrrhenian margin of Italy. Alban Hills lava flows and scoria clasts are made up essentially of clinopyroxenes and leucites and their chemical composition is mostly K-foiditic. Differentiated products (MgO〈3 wt%) are characterized by low SiO2 concentration (〈50 wt%) and geochemical features indicate that this unique differentiation trend is driven by crystal fractionation plus carbonate crust interaction. Notably, the Alban Hills Volcanic District was emplaced into thick limestone units. With the aim of constraining the magmatic differentiation, we performed experiments on the Alban Hills parental composition (plagioclase-free phono-tephrite) under anhydrous, hydrous, and hydrous-carbonated conditions. Experiments were carried out at 1 atm, 0.5 GPa and 1 GPa, temperatures ranging from 1050 to 1300 °C, and H2O and CaCO3 in the starting material up to 2 and 7 wt%, respectively. The experiments performed at 0.5 GPa resulted to be the most representative of the Alban Hills plumbing system. Clinopyroxene and leucite are the main phases occurring under all the investigated conditions and the liquidus phases. Nevertheless, our experimental results demonstrate that the occurrence of CaCO3 in the starting material strongly affects phase relations. Experiments performed under hydrous conditions crystallize magnetite and phlogopite at relatively high temperature. This early crystallization drives the glass composition towards a silica enrichment, resulting in a differentiation trend moving from phono-tephritic (Alban Hills parental composition) to phonolitic compositions. This is in contrast with micro-textural evidences showing late crystallization of magnetite and phlogopite in the natural products and with the composition of the juvenile products. On the contrary, in the CaCO3-bearing experiments (i.e., simulating magma-carbonate interaction) the magnetite and phlogopite stability fields are strongly reduced. As a consequence, the melt differentiation is mainly controlled by the cotectic crystallization of clinopyroxene and leucite, resulting in a differentiation trend moving towards K-foiditic compositions. These experimental results are in agreement with micro-textural features and chemical compositions of Alban Hills natural products and with the magmatic differentiation model inferred by geochemical data. Magma-carbonate interaction is not a rare process and its occurrence has been demonstrated for different plumbing systems. However, the uniqueness of the Alban Hills liquid line of descent suggests that the efficacy of the carbonate contamination process is controlled by different factors, the dynamics of the plumbing system being one of the most important.
    Beschreibung: INGV-DPC Project V3_1 Colli Albani Project FIRB MIUR “Development of innovative technologies for the environmental protection from natural events”.
    Beschreibung: Published
    Beschreibung: On line First
    Beschreibung: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Alban Hills ; ultrapotassic rocks ; experimental petrology ; magma-carbonate interaction ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 74
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    The role of gas percolation in quiescent degassing of persistetly active basaltic volcanoes (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Using constraints from literature data on the petrology and texture of erupted material from Stromboli and geochemical measurements of gas emissions together with a model of gas solubility we construct a conceptual model of quiescent degassing for this volcano. We find that within a pressure range between 100 MPa and 50 MPa (∼3.6 km and ∼1.8 km depth respectively) vesiculating magma ascending within the conduit becomes permeable to gas flow and a transition from closed- to open-system degassing takes place. Above the transition, gas, rich in the most insoluble gases, flows up through degassing magma, and thereby becomes enriched in more soluble gases during ascent to the surface. The final gas emission is therefore a superposition of gases released from magma above the percolation transition and gas that has evolved in closed-system below the transition. Steady-state gas release from Stromboli can only be sustained via magma circulation, driven by the density variation between ascending vesiculating magma and descending degassed magma. By balancing the buoyant force of ascending vesiculating magma against the viscous resistance produced by travelling through descending, degassed magma in a simple flow model we determine that a cylindrical conduit diameter of 2.5–2.9 m produces the magma mass flow rate of 575 kg s−1, required to account for the observed quiescent SO2 gas flux on Stromboli of ∼2.3 kg s−1 (200 td−1).
    Beschreibung: Published
    Beschreibung: 46–60
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Stromboli ; gas ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 75
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    Seismotectonics of strike–slip earthquakes within the deep crust of southern Italy: Geometry, kinematics, stress field and crustal rheology of the Potenza 1990–1991 seismic sequences (Mmax 5.7) (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: We present a revision and a seismotectonic interpretation of deep crust strike–slip earthquake sequences that occurred in 1990– 1991 in the Southern Apennines (Potenza area). The revision is motivated by: i) the striking similarity to a seismic sequence that occurred in 2002 ∼140 km NNW, in an analogous tectonic context (Molise area), suggesting a common seismotectonic environment of regional importance; ii) the close proximity of such deep strike–slip seismicity with shallow extensional seismicity (Apennine area); and iii) the lack of knowledge about the mechanical properties of the crust that might justify the observed crustal seismicity. A comparison between the revised 1990–1991 earthquakes and the 2002 earthquakes, as well as the integration of seismological data with a rheological analysis offer new constraints on the regional seismotectonic context of crustal seismicity in the Southern Apennines. The seismological revision consists of a relocation of the aftershock sequences based on newly constrained velocity models. New focal mechanisms of the aftershocks are computed and the active state of stress is constrained via the use of a stress inversion technique. The relationships among the observed seismicity, the crustal structure of the Southern Apennines, and the rheological layering are analysed along a crustal section crossing southern Italy, by computing geotherms and two-mechanism (brittle frictional vs. ductile plastic strength) rheological profiles. The 1990–1991 seismicity is concentrated in a well-defined depth range (mostly between 15 and 23 km depths). This depth range corresponds to the upper pat of the middle crust underlying the Apulian sedimentary cover, in the footwall of the easternmost Apennine thrust system. The 3D distribution of the aftershocks, the fault kinematics, and the stress inversion indicate the activation of a right-lateral strike–slip fault striking N100°E under a stress field characterized by a sub-horizontal N142°-trending σ1 and a sub-horizontal N232°-trending σ3, very similar to the known stress field of the Gargano seismic zone in the Apulian foreland. The apparent anomalous depths of the earthquakes (N15 km) and the confinement within a relatively narrow depth range are explained by the crustal rheology, which consists of a strong brittle layer at mid crustal depths sandwiched between two plastic horizons. This articulated rheological stratification is typical of the central part of the Southern Apennine crust, where the Apulian crust is overthrusted by Apennine units. Both the Potenza 1990–1991 and the Molise 2002 seismic sequences can be interpreted to be due to crustal E–W fault zones within the Apulian crust inherited from previous tectonic phases and overthrusted by Apennine units during the Late Pliocene–Middle Pleistocene. The present strike–slip tectonic regime reactivated these fault zones and caused them to move with an uneven mechanical behaviour; brittle seismogenic faulting is confined to the strong brittle part of the middle crust. This strong brittle layer might also act as a stress guide able to laterally transmit the deviatoric stresses responsible for the strike–slip regime in the Apulian crust and may explain the close proximity (nearly overlapping) of the strike–slip and normal faulting regimes in the Southern Apennines. From a methodological point of view, it seems that rather simple two-mechanism rheological profiles, though affected by uncertainties, are still a useful tool for estimating the rheological properties and likely seismogenic behaviour of the crust.
    Beschreibung: Published
    Beschreibung: 281–300
    Beschreibung: 3.2. Tettonica attiva
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Strike–slip seismicity; ; Deep crust; ; Active stress; ; Crustal rheology; ; Seismotectonics; ; Southern Apennines ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 76
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    The role of pre-existing thrust faults and topography on the styles of extension in the Gran Sasso range (central Italy) (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Structural analysis and field mapping together with simple geometrical and flexural elastic models, document that two styles of Quaternary extensional tectonics characterized the Gran Sasso range (central Apennines, Italy). In the western part of the range, extension took place on 10–15-km-long range-front normal faults with associated 600–1000-m-high escarpments showing evidence of Late Glacial–Holocene activity. This topography has been reproduced with a thin elastic plate subjected to the isostatic forces induced by the movement along high-angle (55°–65°) planar normal faults. In the eastern part of the belt extension occurred on shallow-dipping normal faults (30°–35°) which reactivated progressively deeper pre-existing thrusts. In this area antithetic "domino" faults formed to accommodate the mechanical adjustment of the hanging-wall over a variably dipping major fault surface. The eastward increase in shortening, due to the earlier compressional phase, documented in the Gran Sasso belt by previous authors, accounts for the more developed zones of weakness and high topographic relief in the eastern sector. This setting could explain the different styles of extension and the more advanced northeastern limit of normal faulting in the eastern sector. This work suggests that normal faults can originate either with low- or high-angle geometry in the upper crust according to the pre-existing tectonic setting and that topography could be important in controlling the geometry and pattern of migrating normal faulting.
    Beschreibung: Published
    Beschreibung: 229-254
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): extensional tectonics ; Quaternary ; thrust faults ; topography ; Apennines ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Dike propagation in volcanic edifices: Overview and possible developments (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Eruptions are often fed by dikes; therefore, better knowledge of dike propagation is necessary to improve our understanding of how magma is transferred and extruded at volcanoes. This study presents an overview of dike patterns and the factors controlling dike propagation within volcanic edifices. Largely based on published data, three main types of dikes (regional, circumferential and radial) are illustrated and discussed. Dike pattern data from 25 volcanic edifices in different settings are compared to derive semi-quantitative relationships between the topography (relief, shape, height, and presence of sector collapses) of the volcano, tectonic setting (presence of a regional stress field), and mean composition (SiO2 content). The overview demonstrates how dike propagation in a volcano is not a random process; rather, it depends from the following factors (listed in order of importance): the presence of relief, the shape of the edifice and regional tectonic control. We find that taller volcanoes develop longer radial dikes, whose (mainly lateral) propagation is independent of the composition of magma or the aspect ratio of the edifice. Future research, starting from these preliminary evaluations, should be devoted to identifying dike propagation paths and likely locations of vent formation at specific volcanoes, to better aid hazards assessment.
    Beschreibung: In press
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 3.2. Tettonica attiva
    Beschreibung: 3.5. Geologia e storia dei sistemi vulcanici
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: 4.3. TTC - Scenari di pericolosità vulcanica
    Beschreibung: JCR Journal
    Beschreibung: open
    Schlagwort(e): dikes ; volcanoes ; topography ; tectonic setting ; eruptions ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 78
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    Unbekannt
    Elemental and isotope covariation of noble gases in mineral phases from Etnean volcanics erupted during 2001–2005, and genetic relation with peripheral gas discharges (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: During 2001–2005, Mount Etna was characterized by intense eruptive activity involving the emission of petrologically different products from several vents, which involved at least two types of magma with different degrees of evolution. We investigated the ratios and abundances for noble-gas isotopes in fluid inclusions trapped in olivines and pyroxenes in the erupted products. We confirm that olivine has the most efficient crystalline structure for preserving the pristine composition of entrapped gases, while pyroxene can suffer diffusive He loss. Both the minerals also experience noble gas air contamination after eruption. Helium isotopes of the products genetically linked to the two different magmas fall in the isotopic range typical of the Etnean volcanism. This result is compatible with the metasomatic process that the Etnean mantle is undergoing by fluids from the Ionian slab during the last ten kyr, as previously inferred by isotope and trace element geochemistry. Significant differences were also observed among olivines of the same parental magma that erupted throughout 2001–2005, with 3He/4He ratios moving from about 7.0 Ra in 2001 volcanites, to 6.6 Ra in 2004–2005 products. Changes in He abundances and isotope ratios were attributed to variations in protracted degassing of the same magma bodies from the 2001 to the 2004–2005 events, with the latter lacking any contribution of undegassed magma. The decrease in 3He/4He is similar to that found from measurements carried out every fifteen days during the same period in gases discharged at the periphery of the volcano. To our knowledge this is the first time that such a comparison has been performed so in detail, and provides strong evidence of the real-time feeding of peripheral emissions by magmatic degassing.
    Beschreibung: Published
    Beschreibung: 683-690
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: JCR Journal
    Beschreibung: open
    Schlagwort(e): fluid inclusions ; noble gases ; helium isotopes ; magma degassing ; olivine ; pyroxene ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 79
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    Unbekannt
    Shifting styles of basaltic explosive activity during the 2002-03 eruption of Mt. Etna, Italy (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: The 2002–03 flank eruption of Etna was characterized by two months of explosive activity that produced copious ash fallout, constituting a major source of hazard and damage over all eastern Sicily. Most of the tephra were erupted from vents at 2750 and 2800 m elevation on the S flank of the volcano, where different eruptive styles alternated. The dominant style of explosive activity consisted of discrete to pulsing magma jets mounted by wide ash plumes, which we refer to as ash-rich jets and plumes. Similarly, ash-rich explosive activity was also briefly observed during the 2001 flank eruption of Etna, but is otherwise fairly uncommon in the recent history of Etna. Here, we describe the features of the 2002–03 explosive activity and compare it with the 2001 eruption in order to characterize ash-rich jets and plumes and their transition with other eruptive styles, including Strombolian and ash explosions, mainly through chemical, componentry and morphology investigations of erupted ash. Past models explain the transition between different styles of basaltic explosive activity only in terms of flow conditions of gas and liquid. Our findings suggest that the abundant presence of a solid phase (microlites) may also control vent degassing and consequent magma fragmentation and eruptive style. In fact, in contrast with the Strombolian or Hawaiian microlite-poor, fluidal, sideromelane clasts, ash-rich jets and plumes produce crystal-rich tachylite clasts with evidence of brittle fragmentation, suggesting that high groundmass crystallinity of the very top part of the magma column may reduce bubble movement while increasing fragmentation efficiency.
    Beschreibung: In press
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Etna ; basaltic explosive activity ; ash-rich jet and plume ; tachylite ; sideromelane ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 80
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    Unbekannt
    Methana, the westernmost active volcanic system of the south Aegean arc (Greece): insight from fluids geochemistry (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: An extensive geochemical survey of the fluids released by the volcanic/geothermal system of Methana was undertaken. Gases were characterized based on the chemical and isotopic [helium (He) and carbon (C)] analysis of 27 samples. Carbon dioxide soil gas concentration and fluxes were measured at 179 sampling sites throughout the peninsula. Forty samples of thermal and cold groundwaters were also sampled and analysed to characterize the geochemistry of the aquifers. Gases of hydrothermal origin gave a preliminary geothermometric estimate of about 210 °C. The He-isotope composition indicated mantle contributions of up to 40%, and the C-isotope composition of CO2 indicated that it predominantly (〉90%) originated from limestone decomposition. The groundwater composition was suggestive of mixing between meteoric and hydrothermally modified sea-water endmembers and water–rock interaction processes limited to simple rock dissolution driven by an increased endogenous CO2 content. All of the thermal manifestations and anomalous degassing areas, although of limited extent, were spatially correlated with the main active tectonic system of the area. The total CO2 output of the volcanic system has been preliminary estimated to be less than 0.05 kg s–1. Although this value is very low compared to those of other volcanic systems, anomalous CO2 degassing at Methana – which is currently restricted to limited areas and at present is the only volcanic risk of the peninsula – is a potential gas hazard that warrants further assessment in future studies.
    Beschreibung: Published
    Beschreibung: 818-828
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Methana ; south Aegean volcanic arc ; fluids geochemistry ; soil gases ; groundwaters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 81
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    Unbekannt
    Methane fluxes from the soils in active volcanic areas: the case of Pantelleria Island (Italy) (2009)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Methane, the most abundant hydrocarbon in the atmosphere, plays an important role in the Earth’s atmospheric chemistry and radiative balance being the second most important greenhouse gas after CO2. Methane is released to the atmosphere by a wide number of sources, both natural and anthropogenic, with the latter being twice as large as the former (Kvenvolden and Rogers, 2005). It has recently been established that significant amounts of geological methane, produced within the Earth’s crust, are currently released naturally into the atmosphere (Etiope, 2004). Among natural sources the volcanic/geothermal emissions are probably the least constrained. Recent estimations for volcanic and geothermal systems in Europe (Etiope et al. 2007) gave a rather large provisional range (4-16 kt/a) that claims for much more field measurements in order to widen the current database and decrease the present uncertainties. Pantelleria is an active volcanic complex, at present in quiescent status, hosting a high enthalpy geothermal system. Explorative geothermal wells tapped an exploitable water-dominated reservoir at 600-800 m depth with maximum measured temperatures of 250 °C. While some data are available on diffuse CO2 fluxes, data on CH4 are available only for fumarolic fluids. In the present study we measured CH4 fluxes in the area of Favara Grande characterized by intense diffuse degassing and widespread signs of geothermal activity (fumaroles, steaming grounds and large zones devoid of vegetation). Values range from negative (-43 to 0 mgCH4 m2 day), typical of soils with methanotrophic activity, up to 3500 mgCH4 m2 day in the most thermalized area. The preliminary estimate of the methane release from the area of Favara Grande is about 2.5 t/a. Extrapolation to the whole volcanic/geothermal system of Pantelleria gives about 10 t/a.
    Beschreibung: Published
    Beschreibung: Davos, Switzerland
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Beschreibung: open
    Schlagwort(e): soil gases ; methane output ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 82
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    Unbekannt
    Geochemical evaluation of observed changes in volcanic activity during the 2007 eruption at Stromboli (Italy) (2009)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: On February 27, 2007 a new eruption started at Stromboli that lasted until April 2 and included a paroxysmal explosion on March 15. Geochemical monitoring carried out over several years revealed some appreciable variations that preceded both the eruption onset and the explosion. The carbon dioxide (CO2) flux from the soil at Pizzo Sopra La Fossa markedly increased a few days before the eruption onset, and continued during lava effusion to reach its maximum value (at 90,000 g m−2 d−1) a few days before the paroxysm. Almost contemporarily, the δ13CCO2 of the SC5 fumarole located in the summit area increased markedly, peaking just before the explosion (δ13CCO2~−1.8‰). Following the paroxysm, helium (He) isotopes measured in the gases dissolved in the basal thermal aquifer sharply increased. Almost contemporarily, the automatic station of CO2 flux recorded an anomalous degassing rate. Also temperatures and the vertical thermal gradient, which had been measured since November 2006 in the soil at Pizzo Sopra La Fossa, showed appreciable variabilities that lasted until the end of the eruption. The geochemical variations indicated the degassing of a new batch of volatile-rich magma that preceded and probably fed the paroxysm. The anomalous 3He/4He ratio suggested that the ascent of a second batch of volatile-rich magma toward the surface was probably responsible of the resumption of the ordinary activity. A comparison with the geochemical variations observed during the 2002–2003 eruption indicated that the 2007 eruption was less energetic.
    Beschreibung: Published
    Beschreibung: 246-254
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): geochemistry ; eruption ; dissolved gases ; Stromboli ; volcanic activity ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 83
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    Unbekannt
    Dike propagation in volcanic edifices: Overview and possible developments (2009)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Eruptions are fed by dikes; therefore, better knowledge of dike propagation is necessary to improve our understanding of how magma is transferred and extruded at volcanoes. This study presents an overview of dike patterns and the factors controlling dike propagation within volcanic edifices. Largely based on published data, three main types of dikes (regional, circumferential and radial) are illustrated and discussed. Dike pattern data from 25 volcanic edifices in different settings are compared to derive semi-quantitative relationships between the topography (relief, shape, height, and presence of sector collapses) of the volcano, tectonic setting (presence of a regional stress field), and mean composition (SiO2 content). The overview demonstrates how dike propagation in a volcano is not a random process; rather, it depends from the following factors (listed in order of importance): the presence of relief, the shape of the edifice and regional tectonic control. We find that taller volcanoes develop longer radial dikes, whose (mainly lateral) propagation is independent of the composition of magma or the aspect ratio of the edifice. Future research, starting from these preliminary evaluations, should be devoted to identifying dike propagation paths and likely locations of vent formation at specific volcanoes, to better aid hazards assessment.
    Beschreibung: Partly fundedwith DPC-INGVfunds (LAVAProject).
    Beschreibung: Published
    Beschreibung: 67–77
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 3.2. Tettonica attiva
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): dikes ; volcanoes ; topography ; tectonic setting ; eruptions ; 03. Hydrosphere::03.04. Chemical and biological::03.04.02. Carbon cycling ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.99. General or miscellaneous ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions ; 05. General::05.08. Risk::05.08.99. General or miscellaneous
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 84
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    Unbekannt
    Intrusion of eccentric dikes: The case of the 2001 eruption and its role in the dynamics of Mt. Etna volcano (2009)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: The 2001 eruption represents one of the most studied events both from volcanological and geophysical point of view on Mt. Etna. This eruption was a crucial event in the recent dynamics of the volcano, marking the passage from a period (March 1993–June 2001) of moderate stability with slow, continuous flank sliding and contemporaneous summit eruptions, to a period (July 2001 to present) of dramatically increased flank deformations and flank eruptions. We show new GPS data and high precision relocation of seismicity in order to demonstrate the role of the 2001 intrusive phase in this change of the dynamic regime of the volcano. GPS data consist of two kinematic surveys carried out on 12 July, a few hours before the beginning of the seismic swarm, and on 17 July, just after the onset of eruptive activity. A picture of the spatial distribution of the sin-eruptive seismicity has been obtained using the HypoDD relocation algorithm based on the double-difference (DD) technique. Modeling of GPS measurements reveals a southward motion of the upper southern part of the volcano, driven by a NNW–SSE structure showing mainly left-lateral kinematics. Precise hypocenter location evidences an aseismic zone at about sea level, where the magma upraise was characterized by a much higher velocity and an abrupt westward shift, revealing the existence of a weakened or ductile zone. These results reveal how an intrusion of a dike can severely modify the shallow stress field, triggering significant flank failure. In 2001, the intrusion was driven by a weakened surface, which might correspond to a decollement plane of the portion of the volcano affected by flank instability, inducing an additional stress testified by GPS measurements and seismic data, which led to an acceleration of the sliding flanks.
    Beschreibung: This work was funded by the Istituto Nazionale di Geofisica e Vulcanologia and by the Dipartimento per la Protezione Civile (Italy).
    Beschreibung: Published
    Beschreibung: 78–86
    Beschreibung: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Beschreibung: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 3.2. Tettonica attiva
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: 4.3. TTC - Scenari di pericolosità vulcanica
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): stress release ; dike ; volcano-tectonics ; flank instability ; Mt. Etna ; instrumental monitoring ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.99. General or miscellaneous ; 05. General::05.02. Data dissemination::05.02.02. Seismological data ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 85
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    New geological insights and structural control on fluid circulation in La Fossa cone (Vulcano, Aeolian Islands, Italy) (2009)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Electric resistivity tomography (ERT), self-potential (SP), soil CO2 flux, and temperature are used to study the inner structure of La Fossa cone (Vulcano, Aeolian Islands). Nine profiles were performed across the cone with a measurement spacing of 20 m. The crater rims of La Fossa cone are underlined by sharp horizontal resistivity contrasts. SP, CO2 flux, and temperature anomalies underline these boundaries which we interpret as structural limits associated to preferential circulation of fluids. The Pietre Cotte crater and Gran Cratere crater enclose the main hydrothermal system, identified at the centre of the edifice on the base of low electrical resistivity values (b20 Ω m) and strong CO2 degassing, SP, and temperature anomalies. In the periphery, the hydrothermal activity is also visible along structural boundaries such as the Punte Nere, Forgia Vecchia, and Palizzi crater rims and at the base of the cone, on the southern side of the edifice, along a fault attributed to the NW main tectonic trend of the island. Inside the Punte Nere crater, the ERT sections show an electrical resistive body that we interpret as an intrusion or a dome. This magmatic body is reconstructed in 3D using the available ERT profiles. Its shape and position, with respect to the Pietre Cotte crater fault, allows replacing this structure in the chronology of the development of the volcano. It corresponds to a late phase of activity of the Punte Nere edifice. Considering the position of the SP, soil CO2 flux, and temperature maxima and the repartition of conductive zones related to hydrothermal circulation with respect to the main structural features, La Fossa cone could be considered as a relevant example of the strong influence of preexisting structures on hydrothermal fluid circulation at the scale of a volcanic edifice.
    Beschreibung: Published
    Beschreibung: 231-245
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: JCR Journal
    Beschreibung: partially_open
    Schlagwort(e): electrical resistivity ; self-potential ; soil CO2 degassing ; temperature ; fluid circulation ; hydrothermal system ; structural boundary ; Vulcano ; La Fossa cone ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 03. Hydrosphere::03.03. Physical::03.03.02. General circulation ; 04. Solid Earth::04.01. Earth Interior::04.01.01. Composition and state ; 04. Solid Earth::04.02. Exploration geophysics::04.02.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 86
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    Unbekannt
    Long-term forecast of eruption style and size at Campi Flegrei caldera (Italy) (2009)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: The Campi Flegrei caldera is an active and restless volcano in the densely inhabited Neapolitan area of southern Italy. Because of the very high value (lives, properties, infrastructures, etc.) exposed to potential volcanic hazards, it is one of the areas at highest volcanic risk on Earth. In such a situation we have made an attempt to contribute to assessment of its volcanic hazards by providing a quantitative probabilistic longterm forecast of style and size of the next eruption. We have evaluated the most relevant physical parameters of the 22 explosive eruptions of the Campi Flegrei caldera over the past 5 ka. This time span has been taken as the reference period for volcanic hazards assessment on the basis of the volcanic and deformation history of the caldera. The evaluated parameters include dispersal, volume and density of the pyroclastic deposits, volume of erupted magma, total erupted mass, and eruption magnitude. The obtained results permit a size classification of the explosive eruptions, which are grouped into three sizes: small, medium, and large. On the basis of the reconstructed eruption dynamics, we have considered a type event(s) representative of each size class and hypothesized the style of the next event. An effusive eruption will likely generate a dome or very small lava flows, while an explosive event of any size very probably will produce particles fallout and flowage of pyroclastic density currents. Using a Bayesian inference procedure, we have assigned a conditional probability of occurrence to each of the eruption size classes. A small-size explosive eruption is the most likely event with a probability of about 60%; a large-size explosive eruption is the least likely event with a probability of about 4%; a medium-size explosive eruption has a probability of occurrence of about 25%; an effusive eruption has about 11% probability of occurrence.
    Beschreibung: Published
    Beschreibung: 265–276
    Beschreibung: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Beschreibung: 4.3. TTC - Scenari di pericolosità vulcanica
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): volcanic hazards assessment ; eruption size ; eruption style ; Campi Flegrei caldera ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 87
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    A multidisciplinary approach to detect active pathways for magma migration and eruption at Mt. Etna (Sicily, Italy) before the 2001 and 2002-03 eruptions (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Two strong flank eruptions occurred in July–August 2001 and from late October 2002 to late January 2003 at Mt. Etna volcano. The two eruptions mainly involved the upper southern flank of the volcano, a particularly active area during the last 30 years, damaging several tourist facilities and threatening some villages. The composite eruptive activity on the upper southern flank of Mt. Etna during 2001–2003 has confirmed “a posteriori” the results of a multidisciplinary study, started well before its occurrence by combining geological, seismic and geochemical data gathered in this part of the volcano. We were able, in fact, to highlight fractured zones likely to be re-activated in the near future in this area, where the largest majority of eruptive fissures in the recent past opened along N120° to N180° ranging directions. The spatial distribution of earthquake epicentres during the period June 30th 2000–June 30th 2001 showed the greatest frequency in a sector compatible with both the direction of the main fissures of the pre-2001 period and that of the 2001 and 2002 lateral eruptions. Soil CO2 and soil temperature surveys carried out in the studied area during the last 3 years have revealed anomalous release of magmatic fluids (mainly CO2 and water vapour) along some NNW–SSE-trending volcano-tectonic structures of the area even during inter-eruptive periods, indicating persistent convective hydrothermal systems at shallow depth connected with the main feeder conduits of Etna. The temporal changes in both seismic and geochemical data from June 30th, 2000 to June 30th, 2001 were compared with the evolution of volcanic activity. The comparison allowed to recognize at least two sequences of anomalous signals (August to December 2000 and April to June 2001), likely related to episodes of step-like magma ascent towards the surface, as indicated by the following eruptive episodes. The N120° to N180° structural directions are in accord with one of the main structural lines affecting eastern Sicily; they would be important pathways for magma uprise to the surface that will keep on feeding the eruptive activity of Etna in the near future. This study also pointed out the high instability of the southern slope of Etna, a sector where the potential hazard by lava flow invasion will remain high also in the near future.
    Beschreibung: Published
    Beschreibung: 20
    Beschreibung: partially_open
    Schlagwort(e): Mt. Etna ; fault detection ; soil gas ; historical eruptive fissures ; eruptive activity ; local seismicity ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 88
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    Fluid circulation and structural discontinuities inside Misti volcano (Peru) inferred from self-potential measurements (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: One of the seven potentially active andesite stratovolcanoes in southern Peru, Misti (5822 m), located 17 km northeast and 3.5 km above Arequipa, represents a major threat to the population (f900,000 inhabitants). Our recent geophysical and geochemical research comprises an extensive self-potential (SP) data set, an audioâ magnetotelluric (AMT) profile across the volcano and CO2 concentrations in the soil along a radial profile. The SP survey is the first of its kind in providing a complete mapping of a large andesitic stratovolcano 20 km in diameter. The SP mapping enables us to analyze the SP signature associated with a subduction-related active volcano. The general SP pattern of Misti is similar to that of most volcanoes with a hydrogeologic zone in the lower flanks and a hydrothermal zone in the upper central area. A quasi-systematic relationship exists between SP and elevation. Zones with constant SP/altitude gradients (Ce) are observed in both hydrogeologic (negative Ce) and hydrothermal (positive Ce) zones. Transition zones between the different Ce zones, which form a concentric pattern around the summit, have been interpreted in terms of lateral heterogeneities in the lithology. The highest amplitudes of SP anomalies seem to coincide with highly resistive zones. The hydrothermal system 6 km in diameter, which extends over an area much larger than the summit caldera, may be constrained by an older, concealed collapse caldera. A sealed zone has apparently developed through alteration in the hydrothermal system, blocking the migration of CO2 upward. Significant CO2 emanations are thus observed on the lower flanks but are absent above the hydrothermal zone.
    Beschreibung: - Institut de Recherche pour le Developpement (IRD) - Instituto Geofısico del Peru´ (IGP)
    Beschreibung: Published
    Beschreibung: 343-360
    Beschreibung: partially_open
    Schlagwort(e): Misti volcano ; self-potential ; audioâ magnetotelluric ; electrical resistivity ; structural discontinuity ; hydrothermal system ; Peru ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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    Dissolved helium isotope ratios in ground-waters: a new technique based on gas–water re-equilibration and its application to Stromboli volcanic system (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Here, a new technique for the determination of dissolved He isotope ratios in ground-waters is presented. This method is based on the extraction and subsequent equilibrium of dissolved gases in an added ‘‘host’’ gas phase. Ultra pure N2 is placed in glass flasks (250 cc), containing water samples, that were hermetically sealed after their collection. After shaking in an ultrasonic bath for 10 min, an aliquot of the separated gas phase was removed from the flask for MS analysis. 3He/4He ratios are measured by using a modified double collector mass spectrometer (VG 5400-TFT). Helium and Ne concentrations are calculated by comparing the partial pressures of masses 4 and 20 of the samples with those of the air-standard measured by a quadrupole mass spectrometer (QMS;VG Quartz). Using He and Ne equilibrium partitioning coefficients, it is possible to calculate the amount of gas originally dissolved in the water. The technique was tested on both air-saturated waters (ASW) and thermal waters from Stromboli (Aeolian Islands, South Italy), the results of which confirmed good reproducibility (ffi5%) and accuracy (ffi3%) of the data. The method was then applied to three thermal water samples collected from the same volcanic area and the results compared with those of a fumarolic and a soil gas. The isotope ratios for dissolved He gave values of 4.06–4.23 Ra, which are significantly higher than those previously reported in the literature (3.0, 3.5 and 2.9 Ra) and that measured at the fumarole (3.09 Ra), suggesting a newer and higher isotopic signature for the volcanic system. The proposed method appears to be a useful tool in the determination of 3He/4He ratios in ground-water systems, especially when free gases are not available or are dangerous to collect.
    Beschreibung: Published
    Beschreibung: 665–673
    Beschreibung: partially_open
    Schlagwort(e): dissolved helium isotopes ; gas water interaction ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 90
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    Isotopic, chemical and dissolved gas constraints on spring water from Popocatepetl volcano (Mexico): evidence of gas–water interaction between magmatic component and shallow fluids (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Geochemical research was carried out on cold and hot springs at Popocatepetl (Popo) volcano (Mexico) in 1999 to identify a possible relationship with magmatic activity. The chemical and isotopic composition of the fluids is compatible with strong gas–water interaction between deep and shallow fluids. In fact, the isotopic composition of He and dissolved carbon species is consistent with a magmatic origin. The presence of a geothermal system having a temperature of 80–1008 C was estimated on the basis of liquid geothermometers. A large amount of dissolved CO2 in the springs was also detected and associated with high CO2 degassing.
    Beschreibung: Published
    Beschreibung: 91– 108
    Beschreibung: partially_open
    Schlagwort(e): Popocatepetl volcano ; helium isotope composition ; carbon isotope composition ; dissolved gases ; gas–water interaction ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 91
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    Magma dynamics in the shallow plumbing system of Mt. Etna as recorded by compositional variations in volcanics of recent summit activity (1995–1999) (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: We describe the reactivation and the successive evolution of the shallow plumbing system of Mt. Etna between the end of the largest flank eruption of the last three centuries (1991–1993) and the subterminal eruption from South-East Crater (SEC), which occurred between February and mid-November 1999. Our analysis is based on observations of the volcanic activity and petrological studies of the erupted volcanics. Bulk rock, mineral and glass compositions have been determined for more than 80 samples erupted from the four summit craters between October 1995 and February 1999. These data allow us to recognise significant compositional variations among the products of different craters. In particular, volcanics produced between 1995 and 1999 by Bocca Nuova (BN), Voragine (VOR) and North-East Crater (NEC) show limited compositional variations and are similar to those observed during recent eruptions (e.g., 1991–93). More primitive magmas have been produced during the more vigorous fire fountains episodes. On the contrary, the South-East Crater produced slightly more differentiated volcanics than those of the other summit craters following its reactivation (November 1996) until the end of 1998. Whole rock compositions of products from this crater show low CaO/Al2O3, whereas interstitial glasses have lower MgO and higher alkali contents than those from the other craters. However, since the beginning of 1999, and just before the start of the subterminal eruption from SEC, the volcanics erupted from this crater progressively changed in composition, becoming similar to those of the other craters. This trend indicates that within the conduits of the summit craters, distinct thermal and fluid-dynamical regimes can evolve, controlling the cooling and crystallisation of Etna magmas.
    Beschreibung: Published
    Beschreibung: 55-71
    Beschreibung: partially_open
    Schlagwort(e): Mount Etna ; crystal fractionation ; petrologic monitoring and magmatic process ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
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  • 92
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    Genesis of fumarolic emissions as inferred by isotope mass balances: CO2 and water at Vulcano Island, Italy (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: We have developed a quantitative model of CO2 and H2O isotopic mixing between magmatic and hydrothermal gases for the fumarolic emissions of the La Fossa crater (Vulcano Island, Italy). On the basis of isotope balance equations, the model takes into account the isotope equilibrium between H2O and CO2 and extends the recent model of chemical and energy two-end-member mixing by Nuccio et al. (1999). As a result,the H2O and CO2 content and the dD, d18O, and d13C isotope compositions for both magmatic and hydrothermal end-members have been assessed. Low contributions of meteoric steam, added at a shallow depth, have been also recognized and quantified in the fumaroles throughout the period from 1988 to 1998. Nonequilibrium oxygen isotope exchange also seems to be occurring between ascending gases and wall rocks along some fumarolic conduits. The d13CCO2 of the magmatic gases varies around -3 to 1‰ vs. Peedee belemnite (PDB), following a perfect synchronism with the variations of the CO2 concentration in the magmatic gases. This suggests a process of isotope fractionation because of vapor exsolution caused by magma depressurization. The hydrogen isotopes in the magmatic gases (-1 to -35‰ vs. standard mean ocean water [SMOW]), as well as the above d13CCO2 value, are coherent with a convergent tectonic setting of magma generation, where the local mantle is widely contaminated by fluids released from the subducted slab. Magma contamination in the crust probably amplifies this effect. The computed isotope composition of carbon and hydrogen in the hydrothermal vapors has been used to calculate the dD and d13C of the entire hydrothermal system, including mixed H2O-CO2 vapor, liquid water, and dissolved carbon. We have computed values of about 10‰ vs. SMOW for water and -2 to -6.5‰ vs. PDB for CO2. On these grounds, we think that Mediterranean marine water (dDH2O 10‰) feeds the hydrothermal system. It infiltrates at depth throughout the local rocks, reaching oxygen isotope equilibrium at high temperatures. Interaction processes between magmatic gases and the evolving seawater also seem to occur, causing the dissolution of isotopically fractionated aqueous CO2 and providing the source for hydrothermal carbon. These results have important implications concerning fluid circulation beneath Vulcano and address the more convenient routine of geochemical surveillance.
    Beschreibung: Published
    Beschreibung: 759–772
    Beschreibung: partially_open
    Schlagwort(e): isotope geochemistry ; volcanic gases ; mixing modeling ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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  • 93
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    Reply to the comment by R.M. Prol-Ledesma on ‘‘Geochemistry of fluids from submarine thermal springs at Punta de Mita, Nayarit, Mexico’’ (2006)
    Elsevier
    In:  Taran Y. A., Inguaggiato S., Marin M., and Yurova L. M. (2002) Geochemistry of fluids from submarine hot springs at Punta de Mita, Nayarit, Mexico. J. Volcanol. Geoth. Res. 115, 329-338.
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: We thank R.M. Prol-Ledesma for her comment on the paper by Taran et al. (2002a) and the new data presented on the water composition of the Punta de Mita (PM) submarine springs. Prol-Ledesma (2003) comments refer to a supposedly wrong citation, superficial description of the geological background, incorrect method of water sampling, wrong approach for the estimation of the end-member composition, irrelevant discussion on the origin of fluids and, lastly, the using of someone else’s ideas and conclusions. In addition, she claims that our data on the fluid chemistry of the springs are not the first (original)ones. The Comment is supported by numerous references to publications by Prol-Ledesma et al. The text below follows the rubrics in the Comment.
    Beschreibung: Published
    Beschreibung: 319-322
    Beschreibung: partially_open
    Schlagwort(e): submarine springs ; hydrothermal systems ; geothermometry ; He-isotopes ; formation waters ; Jalisco Block ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 94
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    S–Cl–F degassing pattern of water-rich alkali basalt: Modelling and relationship with eruption styles on Mount Etna volcano (2007)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Our knowledge of the degassing pattern of sulphur, chlorine and fluorine during ascent and eruption of basaltic magmas is still fragmental and mainly limited to water-poor basalts. Here we model and discuss the pressure-related degassing behaviour of S, Cl and F during ascent, differentiation and extrusion of H2O–CO2-rich alkali basalt on Mount Etna (Sicily) as a function of eruptive styles. Our modelling is based on published and new melt inclusion data for dissolved volatiles (CO2, H2O, S, Cl, F) in quenched explosive products from both central conduit (1989–2001) and lateral dyke (2001 and 2002) eruptions. Pressures are obtained from the dissolved H2O and CO2 concentrations, and vapour–melt partition coefficients of S, Cl and F are derived from best fitting of melt inclusion data for each step of magma evolution. This allows us to compute the compositional evolution of the gas phase during either open or closed system degassing and to compare it with the measured composition of emitted gases. We find that sulphur, chlorine and fluorine begin to exsolve at respective pressures of ∼140 MPa, ∼100 MPa and ≤10 MPa during Etna basalt ascent and are respectively degassed at 〉95%, 22–55%, and ∼15% upon eruption. Pure open system degassing fails to explain gas compositions measured during either lateral dyke or central conduit eruptions. Instead, closed-system ascent and eruption of the volatile-rich basaltic melt well accounts for the time-averaged gas composition measured during 2002-type lateral dyke eruptions (S/Cl molar ratio of 5±1, 35% bulk Cl loss). Extensive magma fragmentation during the most energetic fountaining phases enhances Cl release (55%) and produces a lower S/Cl ratio of 3.7, as actually measured. Comparatively slower magma rise in the central conduits of Etna favours both sulphide saturation of the melt and greater chlorine release (55%), resulting in a distinct S/Cl evolution path and final ratio in eruptive gas. In both eruption types, any previous bubble–melt separation at depth leads to increased S/Cl and S/F ratios in emitted gas. High S/Cl ratios measured during some discrete eruptive events can thus be explained by transitions from closed (deep) to open (shallow) system degassing, with differential gas transfer extending down to ∼2 km depth below the vents. This depth coincides with the base of the volcanic pile where structural discontinuities and the high magma vesicularity (60%) may favour separate gas flow. Finally, the excess S–Cl–F gas discharge through Etna summit craters during non-eruptive periods requires a mixed supply from shallow magma degassing in the volcanic conduits and deeper-derived SO2-rich bubbles from the sub-volcano plumbing system. Our modelling provides a useful reference framework for interpreting the monitored variations of S, Cl and F in Mount Etna gas emissions as a function of volcanic activity. More broadly, the observations made for S, Cl and F degassing on Etna may apply to other basaltic volcanoes with water-rich magmas, such as in arcs.
    Beschreibung: Published
    Beschreibung: 772-786
    Beschreibung: reserved
    Schlagwort(e): Mt Etna ; volatiles ; magma degassing ; eruptive mechanisms ; modelling ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 95
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    Textural effects of steady state behaviour of the Stromboli feeding system (2007)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: The exceptionally persistent activity of Stromboli volcano has lasted for at least 1400 years. The normal strombolian activity is periodically interrupted by more energetic explosions (1–2 per year) and by sporadic effusive episodes (every 10–20 years). Normal activity and effusive episodes are characterized by crystal-rich high-K to shoshonitic basalts issuing from a volatile-poor shallow system. Crystal-poor pumice are emitted only during more violent explosions, and are thought to derive from deep pulses of volatile-rich magma. Shallow level degassing induces massive crystallization of deep pulses of feeding magma that, continuously mixing with the resident one, produces the crystal-rich shoshonite of the persistent activity. We examined the crystallization history of the crystal-rich, shallow reservoir using plagioclase Crystal Size Distribution (CSD) analysis of scoriae and lavas emitted in the past twenty years. CSDs show a linear dependence from crystal size in the size interval 0.06–1.2 mm; number density of larger crystals is biased by right hand truncation effects. CSDs slopes and intercepts are quite constant during the whole considered time span revealing a system that is close to the equilibrium also from a kinetic point of view. The linear crystal size distribution are reached by the system through episodes of growth and resorption, respectively occurring in the degassed and undegassed magma during the continuous mixing in the feeding system. Plagioclase net growth rate (2*10−11 cm/s) results from a balance of growth (10−10 cm/s) and resorption episodes which induce spectacular zoning and resorption textures in crystals larger than 200 μm. CSDs of mafic phases cannot be accurately acquired on each single sample due to poor counting statistics; the evaluation of pyroxene and olivine CSD on the whole data set, however, confirms the conclusions acquired from plagioclase CSDs.
    Beschreibung: Published
    Beschreibung: JCR Journal
    Beschreibung: open
    Schlagwort(e): crystal size distribution ; plagioclase growth ; magma residence time ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 96
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    Physics, chemistry and rheology of silicate melts and glasses (2007)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Knowledge of the physical, chemical and thermodynamic properties of silicate melts and glasses is required to understand magma formation and evolution at all scales of observation. As is illustrated by the papers published in this special issue of Chemical Geology, there is a complex interplay between microscopic and macroscopic features. Whereas determining the microscopic structure of glasses and melts is useful to understand how macroscopic properties vary with pressure, temperature and composition, studies of macroscopic properties in turn put strong constraints on which microscopic aspects are actually relevant to a given problem. In this issue this approach is successfully applied to a variety of topics which range from melt rheology to volatile solubility or from spectroscopic investigations of silicate speciation to computer simulation studies of melt/glass structure. These papers were originally presented and discussed in April 2005 at the Vienna meeting of the European Union of Geosciences. They represent an up-to-date overview of current research in the field, ranging from classical approaches to new science and technology solutions which will help expand our research possibilities. We thank the Chemical Geology staff and all contributors and colleagues who made this volume possible.
    Beschreibung: Published
    Beschreibung: 1
    Beschreibung: open
    Schlagwort(e): NONE ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 97
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    Enclaves provide new insights on the dynamics of magma mingling: a case study from Salina Island (Southern Tyrrhenian Sea, Italy) (2007)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Three lava flows (hereafter, flows A, B, and C) from Salina Island (Italy) consist of basaltic andesitic enclaves dispersed in a dacitic matrix. Enclaves represent 8–12 vol.% of the erupted magma. The number of enclaves and the surface covered by the enclaves at each outcrop do not vary significantly with the distance from the vent in the flows A and B. These feature reflect the dynamics of magma mingling within the reservoir and not the kinematics of the lava flow. In the flow C, these parameters vary irregularly. The statistical entropy S(t) of the enclaves, which is a measure of their spatial distribution (dispersion), is estimated in outcrops located at different distance from the vent. The Kolmogorov–Sinai entropy rate k, which describes the variations of S(t) with time, is also determined. In the lava flow A, S(t) increases linearly with time t for 0btb0.4; k is 0.04. For tN0.5, S(t) attains its maximum value and maintains constant with increasing t. In the lava flow B, S(t) linearly increases with t, and k is 0.01. In the lava flow C, there is not correlation between S(t) and t. The comparison between the results from the analysis of the Porri enclaves and those from numerical experiments on the variation of S(t) in chaotic advective mixing systems and from previous experimental models on magma mixing, allow us to draw some conclusions on dynamics of the basaltic andesite– dacite mingling in the magma chamber. Fully chaotic magma mingling systems show three evolution stages. An initial stage, which is unknown because of the disruption of the initial configuration of the interacting magmas, a second stage characterized by a linear increase of the statistical entropy with time, and a third stage, in which the uniformity of the system is reached, and the entropy does not vary with increasing time. A system in which the uniformity is never attained, is characterized by irregular variations of S(t) with time. In the flows A and B, the relations between S(t) and t are consistent with those of a fully chaotic dynamics possibly associated to convection. The basaltic andesite was uniformly distributed in the dacitic host due to the occurrence of convective movements driven by the injection of the basaltic andesite within the dacitic chamber. The mingling system recorded by the lava flow A evolved with a higher rate with respect to that of the flow B. This suggests that chaotic advection (stirring and folding) is more efficient in the magmatic system A than in B. On the contrary, the mingling system C is characterized by a non-uniform distribution of the basaltic andesite within dacite. This reflects the occurrence of a dynamics in which stirring and folding processes do not operate efficiently and are unable to uniformly distribute the dispersed phase within the continuous one. The decrease of k from A to B, and the lack of a measurable k in C, along with the observation that A and B were emitted before C, indicate that the efficiency of advective movements within the Porri magma chamber declined with decreasing time. Mingled magmas characterized by a homogeneous spatial distribution of enclaves or an initially inhomogeneous distribution evolving towards a homogeneous one are indicative of efficient advection processes that may favor magma mixing. Mingled magmas characterized by an inhomogeneous distribution of enclaves suggest low dynamical interaction between the two end-members. Magma mixing is not allowed.
    Beschreibung: Published
    Beschreibung: 128–140
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): volcanology ; petrology ; magma mingling ; enclaves ; lava flows ; entropy ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 98
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    The December 2002–July 2003 effusive event at Stromboli volcano, Italy: Insights into the shallow plumbing system by petrochemical studies (2007)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: On 28 December 2002, the persistent Strombolian activity at Stromboli was interrupted by the sudden onset of lava emission onto the Sciara del Fuoco slope, a horseshoe-shaped depression on the NW flank of the volcano. The effusive episode went on until 22 July 2003 and produced a cumulative volume of lavas of 11×106 m3 ranking the event as the largest occurred in the past 30 years. The eruptive vents were mainly located in the NE sector of the Sciara del Fuoco depression, at an elevation of 550–600 m a.s.l. On 30 December, the eastern portion of the Sciara del Fuoco collapsed producing a tsunamigenic landslide. On 5 April 2003, a paroxysmal eruption occurred at the summit craters during which crystal-poor pumiceous products were emitted. The paroxysm did not interrupt the lava emission. The Strombolian activity at the summit craters gradually resumed starting from March 2003 and fully recovered by the end of July. Periodic sampling of the lava at the active vents was carried out during the entire effusive event. All the analysed samples are shoshonitic basalts (SiO2 48.5–50.4 wt.%; K2O 2.1–2.4 wt.%) in the range of composition observed in the products erupted during the past 20 years. They bear about 50 vol.% zoned crystals of plagioclase An90–60, diopside–augite and olivine Fo70–73 in a compositionally homogeneous shoshonitic groundmass. Bulk rock major and trace element contents measured with different methodologies at different laboratories show only minor variations. Sr and Nd isotope ratios are close to those of the crystal-rich scoriae erupted in the previous years. Despite of small compositional variations related to the emptying of the zoned topmost portion of the conduit, the data show that the switch from Strombolian explosive to effusive activity is not associated with changes of the textures and composition of the erupted products. Slight but somehow systematic variation of trace elements and isotope ratios between products erupted before and after the 5 April eruption are likely accounted by limited mixing between the fresh, volatile-rich, crystal-poor, magma erupted as pumice during the paroxysm, and the volatile-poor, crystal-rich magma feeding the lava flow. The uniform composition of the erupted lava indicates the presence of a large volume of well-mixed, crystal-rich, homogeneous magma residing in the shallow plumbing system of the volcano. Two possible trigger mechanism of the effusive event are here proposed: (i) a discrete input of fresh magma into the lower part of the shallow magmatic system occurred some months before the eruption and was followed by crystallisation, degassing and mixing with the crystal-rich shallow magma which re-homogenised the system. These processes eventually led to the rise of the magma at a higher level and failure of the conduit walls. (ii) The onset of the effusion may represent the consequence of a gradual rise of the magma level in the conduits occurred in the past two decades. The process of progressive refilling, initiated after the 1985 effusive eruption, ultimately culminated on 28 December 2002 with the failure of the conduit wall and the opening of vents 100–150 m below the summit craters
    Beschreibung: Published
    Beschreibung: 263-284
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Stromboli volcano ; Aeolian Islands ; 2002–2003 eruption ; Mineralogy ; Geochemistry ; Sr isotope ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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    Natural emissions of methane from geothermal and volcanic sources in Europe (2007)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: It has recently been demonstrated that methane emission from lithosphere degassing is an important component of the natural greenhouse-gas atmospheric budget. Globally, the geological sources are mainly due to seepage from hydrocarbon-prone sedimentary basins, and subordinately from geothermal/volcanic fluxes. This work provides a first estimate of methane emission from the geothermal/volcanic component at European level. In Europe, 28 countries have geothermal systems and at least 10 countries host surface geothermal manifestations (hot springs, mofettes, gas vents). Even if direct methane flux measurements are available only for a few small areas in Italy, a fair number of data on CO2, CH4 and steam composition and flux from geothermal manifestations are today available for 6 countries (Czech Republic, Germany, Greece, Iceland, Italy, Spain). Following the emission factor and area-based approach, the available data have been analyzed and have led to an early and conservative estimate of methane emission into the atmosphere around 10,000 ton/yr (4000–16,000 ton/yr), basically from an area smaller than 4000 km2, with a speculative upper limit in the order of 105 ton/yr. Only 4–18% of the conservative estimate (about 720 ton/yr) is due to 12 European volcanoes, where methane concentration in volcanic gases is generally in the order of a few tens of ppmv. Volcanoes are thus not a significant methane source. While the largest emission is due to geothermal areas, which may be situated next to volcanoes or independent. Here inorganic synthesis, thermometamorphism and thermal breakdown of organic matter are substantial. Methane flux can reach hundreds of ton/yr from small individual vents. Geothermal methane is mainly released in three countries located in the main high heat flow regions: Italy, Greece, and Iceland. Turkey is likely a fourth important contributor but the absolute lack of data prevents any emission estimate. Therefore, the actual European geothermal–volcanic methane emission could be easily projected to the 105 ton/yr levels, reaching the magnitude of some other natural sources such as forest fires or wild animals.
    Beschreibung: Published
    Beschreibung: 76-86
    Beschreibung: 4.5. Degassamento naturale
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Methane ; volcanoes ; Geothermal vents ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
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    Textural effects of steady state behaviour of the Stromboli feeding system (2007)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: The exceptionally persistent activity of Stromboli volcano has lasted for at least 1400 years. The normal strombolian activity is periodically interrupted by more energetic explosions (1–2 per year) and by sporadic effusive episodes (every 10–20 years). Normal activity and effusive episodes are characterized by crystal-rich high-K to shoshonitic basalts issuing from a volatile-poor shallow system. Crystal-poor pumice are emitted only during more violent explosions, and are thought to derive from deep pulses of volatile-rich magma. Shallow level degassing induces massive crystallization of deep pulses of feeding magma that, continuously mixing with the resident one, produces the crystal-rich shoshonite of the persistent activity. We examined the crystallization history of the crystal-rich, shallow reservoir using plagioclase Crystal Size Distribution (CSD) analysis of scoriae and lavas emitted in the past twenty years. CSDs show a linear dependence from crystal size in the size interval 0.06–1.2 mm; number density of larger crystals is biased by right hand truncation effects. CSDs slopes and intercepts are quite constant during the whole considered time span revealing a system that is close to the equilibrium also from a kinetic point of view. The linear crystal size distribution are reached by the system through episodes of growth and resorption, respectively occurring in the degassed and undegassed magma during the continuous mixing in the feeding system. Plagioclase net growth rate (2 × 10− 11 cm/s) results from a balance of growth (10− 10 cm/s) and resorption episodes which induce spectacular zoning and resorption textures in crystals larger than 200 μm. CSDs of mafic phases cannot be accurately acquired on each single sample due to poor counting statistics; the evaluation of pyroxene and olivine CSD on the whole data set, however, confirms the conclusions acquired from plagioclase CSDs.
    Beschreibung: Published
    Beschreibung: 86-98
    Beschreibung: 2.4. TTC - Laboratori di geochimica dei fluidi
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): crystal size distribution ; plagioclase growth ; magma residence time ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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