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  • Elsevier  (106,256)
  • Annual Reviews
  • 2005-2009  (106,845)
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  • 2008  (106,845)
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  • 1
    Publication Date: 2020-10-29
    Description: 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.
    Description: Published
    Description: 91-101
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: 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)
    Type: article
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  • 2
    Publication Date: 2020-10-29
    Description: The bulk electrical conductivity of the phonotephritic lava from the 1944 eruption of Mt Vesuvius was measured using complex impedance spectroscopy in a multianvil apparatus at 1 GPa and temperatures up to 700 °C. Melting experiments prior to the electrical measurements were also performed on this sample in a piston cylinder apparatus in order to gauge how bulk conductivity varies as a function of its melt fraction. Unlike the behaviour found in basaltic rocks in which conductivity increases with increasing melt fraction, we observe a conductivity decrease of the order of a factor of ten for samples at 700 °C ranging in melt fraction from 32 vol.% to completely molten.We attribute this anomalous behaviour to the progressive loss of highly conductive leucite upon melting. The addition of potassium to the melt phase, however, does not result in an increase of the total alkali concentration due to the melting of other mineral components. We also present an empirical model to predict the electrical conductivity of fully molten silicate liquids as a function of temperature and chemical composition, based on conductivity data for natural silicate liquids found in the literature. The inclusion of compositional terms reduces the error by more than a factor of four with respect to a composition independent, temperature-only parameterization.
    Description: Published
    Description: 192-201
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: Electrical conductivity ; silicate melts ; partial melting ; Mt. Vesuvius ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 3
    Publication Date: 2020-11-19
    Description: We report on structural and anisotropy of magnetic susceptibility (AMS) results from the Upper Miocene sediments of the Amantea basin, located on the Tyrrhenian coast of the Calabrian Arc (Southern Italy). The stratigraphic succession of the basin is organized in three depositional sequences, separated by two major angular unconformities. Detailed geologica1 mapping and structural analysis demonstrate that the stratigraphic evolution of the Amantea basin is strongly controlled by a synsedimentary extensional tectonic regime. Severa1 NNE-SSW-trending norma1 fault arrays with large scatter in inclination values have been interpreted as due to a domino faulting mechanism, consistent with a WNW-ESE stretching direction. AMS data have been obtained for 13 sites, both in the not constrained in age first depositional sequence (3 sites), and in the upper Tortonian-lower Messinian clays from the second depositional sequence (10 sites). Al1 the sites show a strong magnetic foliation parallel to the bedding planes, and a well defined magnetic lineation subparallel to the local bedding dip directions. The magnetic lineations cluster around a WNW-ESE trend and are parallel to the stretching directions inferred by fault-slip analysis and basin architecture. These new data then confirm the possibility to use the magnetic lineation to map the strain trajectory in weakly deformed extensional sedimentary basins. Paleomagnetic data (from previous studies) show that the whole Calabrian block underwent a 15°-20° clockwise rotation probably in the Pleistocene, postdating the extensional tectonic events which controlled the Amantea basin geometry. Therefore we suggest for the Amantea basin an original E-W-oriented stretching direction, which may be considered as the older extensional direction characterizing the Late Miocene evolution of the southern Tyrrhenian Sea domain.
    Description: Published
    Description: 33-49
    Description: JCR Journal
    Description: reserved
    Keywords: magnetic fabric ; extentional tectonics ; Miocene ; Calabrian Arc ; Italy ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
    Publication Date: 2020-11-26
    Description: 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.
    Description: Published
    Description: 281-294
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: 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
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  • 5
    Publication Date: 2020-11-17
    Description: We investigate the P wave velocity structure and the Vp/Vs ratio beneath the Italian peninsula down to 100 and 60 km depth respectively by seismic travel time tomography. We invert data provided by the International Seismological Centre (ISC) (1997–2005), making use of some alternative strategies for the travel time approach in a well constrained and worldwide adopted code (SIMULPS). Resolution for the different layers is discussed and sensitivity analyses are performed through test inversions to explore the resolution characteristics of the model at different spatial scales. The resulting tomographic images provide a detailed sketch of the P wave anomalies, clearly showing, among the other features, the shape of the Ivrea body in the Western Alps, the upwelling of the oceanic crust in the Ligurian Sea and the slab under the Calabrian arc. They are less informative for the Vp/Vs ratio. Nevertheless, some features are very interesting and deserve further investigation like the anomalous decrease of the Vp/Vs ratio under the Ligurian Sea or the variations of the Vp/Vs ratio calculated in the first 10 km depth of the Apenninic region with respect to the lower values of the Alpine region at the same depth. The tomographic cross sections reveal a continuous superposition of two kinds of crusts (transitional over Adriatic) all along the peninsula but do not show any slab, intended as a clear, vertical downgoing high velocity material in either the northern or central Apennines.
    Description: Published
    Description: 1-23
    Description: 4T. Sismicità dell'Italia
    Description: JCR Journal
    Description: reserved
    Keywords: Seismic tomography ; Lithospheric structure ; Vp/Vs ratio ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
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  • 6
    Publication Date: 2020-12-21
    Description: A sedimentary sequence spanning Marine Isotope Stage (MIS) 6 to MIS 2 in core LC07, recovered in the central Mediterranean, has been investigated in order to produce a high-resolution paleoceanographic reconstruction. The changes in productivity deduced from calcareous plankton relative abundances and independently confirmed by the BaXS fluctuations are linked to the stability of the water column which is mainly controlled by the water mass temperature. During glacial intervals, productivity was generally enhanced. Oligotrophic and warmer water masses with a deepened seasonal thermocline can be inferred for most of MIS5. The magnetic properties of the sediment show increased occurrences of North Africa dust in the central Mediterranean during cold phases, likely as a consequence of a more efficient erosive process triggered by southward displacement of the intertropical convergence zone. Although increases in both productivity and Saharan dust occurred during cold periods, the atmospheric inputs do not seem to contribute significantly to the fertilization of primary producers. A Shannon Index curve has been used to tentatively synthesize the variations of calcareous nannofossil assemblages through the last 150 kyr. The assemblage diversity sharply increased coincident with the transition from the penultimate glacial to the last interglacial, subsequently low diversity was gradually reached again in the last glacial.
    Description: Published
    Description: 26-41
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: calcareous nannofossils ; foraminifera ; paleoproductivity ; Late Pleistocene ; central mediterranean ; 03. Hydrosphere::03.01. General::03.01.06. Paleoceanography and paleoclimatology ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism
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  • 7
    Publication Date: 2020-12-21
    Description: The lithological and compositional characteristics of eighteen different pyroclastic deposits of Campanian origin, dated between 125 cal ky BP and 22 cal ky BP, were described. The pyroclastic deposits were correlated among different outcrops mainly located on the Apennine slopes that border the southern Campanian Plain. They were grouped in two main stratigraphic and chronologic intervals of regional significance: a) between Pomici di Base (22.03 cal ky BP; Somma–Vesuvius) and Campanian Ignimbrite (39 cal ky BP; Campi Flegrei) eruptions; and b) older than Campanian Ignimbrite eruption. Three new 14C AMS datings support the proposed correlations. Six eruptions were attributed to the Pomici di Base- Campanian Ignimbrite stratigraphic interval, while twelve eruptions are older than Campanian Ignimbrite. Of the studied deposits two originated from Ischia island, five are related to Campi Flegrei, and three to Somma– Vesuvius. Two eruptions have an uncertain correlation with Somma–Vesuvius or Campi Flegrei, while six eruptions remain of uncertain source. Minimum volumes of five eruptions were assessed, ranging between 0.5 km3 and 4 km3. Two of the studied deposits were correlated with Y-3 and X-5 tephra layers, which are widely dispersed in the central Mediterranean area. The new stratigraphic and chronologic data provide an upgraded chrono-stratigraphy for the explosive activity of Neapolitan volcanoes in the period between 125 and 22 cal ky BP.
    Description: Published
    Description: 19–48
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: JCR Journal
    Description: reserved
    Keywords: Neapolitan volcanoes ; late Pleistocene ; explosive eruptions ; Somma–Vesuvius ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
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  • 8
    Publication Date: 2021-01-07
    Description: 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
    Description: Published
    Description: 89–102
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: 4.5. Degassamento naturale
    Description: JCR Journal
    Description: reserved
    Keywords: 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
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  • 9
    Publication Date: 2021-05-12
    Description: Although the tectonic features and stress regime typical for accretionary complexes and back-arc domains have been widely documented so far, few are known on the transitional zone separating these two systems. Here we report on structural analysis and anisotropy of magnetic susceptibility (AMS) results from Eocene–Pliocene sediments exposed in western Sardinia. From late Oligocene to middle Miocene, the studied area was located between the Alpine–Apennine wedge to the east, which was undergoing shortening and accretion, and the Liguro–Provenc al basin, undergoing extension and spreading. We find that, prior to the formation of the Liguro–Provenc al basin, the middle Eocene–lower Oligocene sediments cropping out at the southwesternmost edge of Sardinia were subjected to NE–SW shortening (in present-day coordinates), in agreement with recently reported geological information. Conversely, the upper Oligocene–Pliocene sedimentary sequences record a different evolutionary stage of extensional processes. Upper Oligocene–middle–upper Burdigalian sediments clearly show a N–S-oriented magnetic lineation that can be related to extensional direction along the prevalent E–W-oriented normal faults. On the other hand, no magnetic lineation has been detected in upper Burdigalian–Serravallian sediments, which mark the end of the first rifting process in Sardinia, which likely coincides with the rift-to-drift transition at the core of the Liguro–Provençal basin. Finally, a NE–SW extension is observed in two Tortonian–Pliocene sites at the northwestern margin of the NNW–SSE-oriented Campidano graben. Our study confirms that AMS may represent a valuable strain-trajectory proxy and significantly help to unravel the characters of temporally superimposed tectonic events.
    Description: Published
    Description: 213-232
    Description: 3.4. Geomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: Back-arc basin ; Magnetic anisotropy susceptibility (AMS) ; Sardinia ; Mediterranean area ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology
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  • 10
    Publication Date: 2020-11-17
    Description: Mt. Etna in Sicily (Italy) is one of the best monitored basaltic volcanoes in the world due to the frequent eruptions from its summit and flanks. Routine monitoring carried out by the Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Catania, for surveillance purposes permits following the evolution of volcanic events. In this paper, a description of the ash monitoring system as occurred during the August-December 2006 summit eruption at the Southeast Crater (SEC) is shown. This eruption was characterized by lava flow effusions and vigorous Strombolian activity. Eighteen paroxysmal episodes occurred up to the end of November, forming weak ash plumes accompanied by moderate tephra fallout over Etna’s slopes. During these events, we applied a multidisciplinary approach to promptly monitor the paroxysmal activity and the associated tephra fallout, through analysis from seismic tremor and observation from live-cameras, sampling operations, mapping and analysis of the deposit. During the most significant episodes, we carried out textural and grain-size analysis on tephra samples and evaluated the whole grain-size deposit and the erupted volume, while numerical simulations of tephra dispersal allowed better understanding eruptive dynamics. An example of this methodology is applied to the 16 November episode, during which seismic tremor furnished important constraints on the chronology. This paroxysmal eruption produced light fallout on the north-east sector of the volcano for about ten hours and a number of debris-avalanches over the slopes of the SEC cone. The erupted deposit was composed for the most part of lithic components and characterized by a whole grain-size distribution centered on 2.2 , while its total mass was evaluated 7 x 106 kg. On the whole, such integrated studies help to obtain information on magma fragmentation and eruptive mechanisms, to characterize the explosive styles shown by Etna and finally, to better approach the monitoring of imminent eruptions.
    Description: FIRB Italian project “Sviluppo Nuove Tecnologie per la Protezione e Difesa del Territorio dai Rischi Naturali” funded by Italian Minister of University and Research
    Description: Published
    Description: 123-134
    Description: 5V. Processi eruttivi e post-eruttivi
    Description: JCR Journal
    Description: open
    Keywords: Mt. Etna ; volcanic ash monitoring ; tephra deposit ; 2006 eruption ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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  • 11
    Publication Date: 2021-01-14
    Description: The viscosity of an iron-bearing melt with composition similar to Unzen andesite was determined experimentally in the high (109-1010.5 Pa·s) and low (5-1000 Pa·s) viscosity range using a parallel plate viscometer and the falling sphere method, respectively. Falling sphere experiments were carried out in an internally heated argon pressure vessel and in a piston cylinder apparatus at 1323 to 1573 K and 200 to 2000 MPa. Creep experiments were performed in the temperature range of 747 - 845 K at 300 MPa. The water content of the melt varies from nominally dry to 6.2 wt% H2O. The Fe2+/Fetot ratio was determined for each sample in the quenched glass using a colorimetric method. Pressure has minor influence on the viscosity compared with the effect of temperature, water content (main compositional parameter controlling the viscosity) or with the Fe2+/Fetot ratio (especially important at low water content of the melt). Based on our new viscosity data and literature data with measured Fe2+/Fetot ratio we propose a new empirical equation to estimate the viscosity η (in Pa·s) of andesitic melts as a function of temperature T (in K), water content w (in wt%) and Fe2+/Fetot ratio. The derived relationship reproduces the experimental data (87 in total) in the viscosity range from 100.5 to 1013 Pa·s with a 1σ standard deviation of 0.17 log units. However, application of this calculation model is limited to Fe2+/Fetot〉0.3 and to temperatures above Tg. Moreover, in the high viscosity range the variation of viscosity with water content is constrained only by few experimental data and needs verification by additional measurements. The viscosity data are used to interpret mixing processes in the Unzen magma chamber prior to 1991-1995 eruption. We demonstrate that the viscosities of the rhyolite and andesite melts from the two end-member magmas are nearly identical prior and during mixing, enabling efficient magma mixing.
    Description: Published
    Description: 208-217
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: open
    Keywords: viscosity ; andesite melt ; dissolved water ; redox state of iron ; Unzen ; magma mixing ; 04. Solid Earth::04.04. Geology::04.04.07. Rock geochemistry
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  • 12
    Publication Date: 2021-07-14
    Description: Field geological data of the Pantelleria Island, a large Late Quaternary volcano located in the Sicily Channel rift zone, integrated with offshore geophysical information, are used to derive the structural setting of the Island and the surrounding region, and to analyse the relationships between tectonics and magmatism. Field work shows that the principal faults exposed on the Island fall into two systems trending NNE–SSW and NW–SE. Mapped faults from offshore multichannel seismic profiles show similar trends, and some of them represent the offshore extension of the Pantelleria Island structures. The NW–SE faults bound the Pantelleria Graben, one of the three main depressions formed since the Late Miocene–Early Pliocene within the African continental platform, which compose the Sicily Channel rift zone. A 3-D Moho depth geometry, derived from inversion of Bouguer gravity data, shows a significant uplift of the discontinuity up to 16–17 km beneath the westernmost part of the Pantelleria Graben and beneath the Pantelleria Island; it lows rapidly to 24–25 km away from the graben northeastward and south-westward. The Moho uplift could explain the presence of a shallow magma chamber in the southern part of the Island, where processes of magmatic differentiation are documented. Geological and geophysical data suggest that the northwestern part of the Sicily Channel is presently dominated by a roughly E–W directed extensional regime. Crustal cracking feeding the Quaternary volcanism could be also related to this extensional field that would be further responsible for the development of the N–S trending volcanic belt that extends in the Sicily Channel from Lampedusa Island to the Graham Bank. This mode of deformation is confirmed also by geodetic data. This implies that in the northwestern part of the Sicily Channel, the E–W extension replaced the NE–SW crustal stretching that originated the NW-trending tectonic depressions constituting the rift zone. © 2008 Elsevier B.V. All rights reserved.
    Description: Published
    Description: 32-46
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: Pantelleria Island ; Channel rift zone ; structural analysis ; Quaternary volcanism ; gravity modelling ; tectonic extension ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology
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  • 13
    Publication Date: 2020-11-16
    Description: The MAGFLOW cellular automata model was able to fairly accurately reproduce the time of the lava flow advance during the 2006 Etna eruption leading to very plausible flow predictions. MAGFLOW is intended for use in emergency response situations during an eruption to quickly forecast the lava flow path over some time interval from the immediate future to a long-time forecast. Major discrepancies between the observed and simulated paths occurred in the early phase of the 2006 eruption due to an underestimation of the initial flow rate, and at the time of the overlapping with the 2004-2005 lava flow. Very good representations of the areas likely to be inundated by lava flows were obtained when we adopt a time-varying effusion rate and include the 2004-2005 lava flow field in the Digital Elevation Model (DEM) of topography.
    Description: Published
    Description: 1050-1060
    Description: 5V. Processi eruttivi e post-eruttivi
    Description: JCR Journal
    Description: open
    Keywords: Lava Flow ; Etna volcano ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.01. Computational geophysics::05.01.02. Cellular automata, fuzzy logic, genetic alghoritms, neural networks ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation
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  • 14
    Publication Date: 2020-11-16
    Description: Here we report the results of the analysis of a GPS velocity field in the Umbria–Marche Apennines (central Italy) obtained from the integration of diverse geodetic networks. The velocity field obtained shows a high degree of consistency both spatially and in terms of comparison with independent information, despite the limited time span of some GPS stations. Starting from the velocity field we derive a continuous strain rate field applying a spline interpolation technique which provide a smooth estimate of the deformation field. The main feature of the resulting strain rate field is a continuous high (N50 nanostrain/year) strain rate belt coincident with the area of largest historical and instrumental seismic release. The model directions of the principal axes agree with geological and seismological information indicating NE–SW extension. We transform the strain rate field into geodetic moment rate using the Kostrov formula to evaluate the potential seismic activity of the region and compare it with actual seismic release in the last 720 years from MwN5.5 earthquakes. This comparison highlights a large possible deficit in the seismic release with respect to the overall potential seismic activity, particularly concentrated in the northern part of the study area. This discrepancy can be resolved with either a large amount of seismicity to be released in the near future or significant aseismic slip and deformation.
    Description: Published
    Description: 3-12
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Description: reserved
    Keywords: GPS ; crustal deformation ; Northen Apennines ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
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  • 15
    Publication Date: 2020-11-25
    Description: The Mesa del Caballo trench assessment confirms the Holocene activity of the main strand of the Boconó fault at the Apartaderos pull-apart basin. Fifteen earthquakes, of which fourteen have been radiocarbon dated, have been recognized, spanning the last 20,500 yr. Recurrence intervals of these ≥7 magnitude events are variable. The dominant mode of recurrence is 400–450 yr, and the second one is 900 yr. Eventually some events are 1400–1800 yr apart. We suspect that our seismic record may be incomplete. This could be easily justified by several conditions: most of the earthquake recognitions is based on open-crack filling and they superpose spatially (eventually masking or destroying older fills), trenching may miss some events because the fault is made of en echelon Riedel shears, and a short return period may lead to faint differences between paleosoils few hundreds years of age apart. This trench also images an older activity of the fault, as evidenced by plentiful earthquake-triggered liquefaction features, as well as slumping and rotational sliding. By comparing paleoseismic results between the Morro de Los Hoyos and Mesa del Caballo trenches, it appears that both fault strands bounding the Apartaderos pull-apart basin move simultaneously. Besides, the main strand also coseismically slips twice in between those common events. In other words, the seismic scenario could be that the northern strand recurs every 1200–1350 yr while the southern does every 400– 450 yr. This is also in agreement with a respective slip share of 25 and 75% of the 9–10 mm/yr average slip of the Boconó fault in the Mérida Andes central sector.
    Description: Published
    Description: 38-53
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: Active faults ; South America ; Paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 16
    Publication Date: 2020-12-14
    Description: This paper presents a new methodology for studying the evolution of curved mountain belts by means of paleomagnetic analyses performed on analogue models. Eleven models were designed aimed at reproducing various tectonic settings in thin-skinned tectonics. Our models analyze in particular those features reported in the literature as possible causes for peculiar rotational patterns in the outermost as well as in the more internal fronts. In all the models the sedimentary cover was reproduced by frictional low-cohesion materials (sand and glass micro-beads), which detached either on frictional or on viscous layers. These latter were reproduced in the models by silicone. The sand forming the models has been previously mixed with magnetite-dominated powder. Before deformation, the models were magnetized by means of two permanent magnets generating within each model a quasi-linear magnetic field of intensity variable between 20 and 100 mT. After deformation, the models were cut into closely spaced vertical sections and sampled by means of 1x1-cm Plexiglas cylinders at several locations along curved fronts. Care was taken to collect paleomagnetic samples only within virtually undeformed thrust sheets, avoiding zones affected by pervasive shear. Afterwards, the natural remanent magnetization of these samples was measured, and alternating field demagnetization was used to isolate the principal components. The characteristic components of magnetization isolated were used to estimate the vertical-axis rotations occurring during model deformation. We find that indenters pushing into deforming belts from behind form non-rotational curved outer fronts. The more internal fronts show oroclinal-type rotations of a smaller magnitude than that expected for a perfect orocline. Lateral symmetrical obstacles in the foreland colliding with forward propagating belts produce non-rotational outer curved fronts as well, whereas in between and inside the obstacles a perfect orocline forms only when the ratio between obstacles’ distance and thickness of the cover is greater than 10. Finally, when a belt collides with an obstacle in the foreland oblique to the shortening direction the outer front displays rotations opposite in sign to oroclinal-type rotations, whereas the internal fronts seem to assume an "oroclinal type" rotational pattern. Furthermore rotation is easier in laterally unconfined models, i.e. when the wedge can "escape" laterally. The results from our models may be useful when compared to paleomagnetic rotations detected in natural arcs. In these cases, our results may allow for better understanding the tectonic setting controlling the genesis of curved mountain fronts, as is the case of the Gela Nappe of Sicily we compare with some of our models.
    Description: Published
    Description: 633-654
    Description: JCR Journal
    Description: reserved
    Keywords: paleomagnetism ; tectonic rotations ; physical models ; arcuate belts ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 17
    Publication Date: 2020-12-09
    Description: This work presents the results of an assessment of the existence and concentration of 13 volatile organic compounds (VOCs) in groundwaters from 14 hydrological basins in Sicily (25,710 km2). On the basis of hydrological, hydrogeochemical and geological studies, 324 sampling points were selected. All groundwater sampled were collected twice, from October to December 2004 and from February to May 2005, and were analysed to determine the concentration and spatial distribution of the VOCs in the aquifers. The need to analyze a large number of samples in a short space of time so as to obtain quantitative analyses in trace concentration levels spurred us to create a new analytical method, both simple and sensitive, based on HS-SPME/GC/MS. The concentrations of VOCs measured in industrial and intensive agricultural unconfined aquifers were greater than those found in other aquifers. Tetrachloroethylene, chloroform, trichloroethylene and 1,2-dichloropropane were the most frequently detected VOCs. However, they exceeded the guideline values proposed by the EU in only three aquifers located near to industrial and intense agricultural areas.
    Description: Published
    Description: 3563-3577
    Description: 4.4. Scenari e mitigazione del rischio ambientale
    Description: JCR Journal
    Description: reserved
    Keywords: groundwater pollution ; VOCs ; aliphatic compounds ; groundwater monitoring ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 18
    Publication Date: 2020-12-07
    Description: A geochemical survey of thermal waters collected from submarine vents at Panarea Island (Aeolian Islands, southern Italy) was carried out from December 2002 to March 2007, in order to investigate i) the geochemical processes controlling the chemical composition of the hydrothermal fluids and ii) the possible relations between the chemical features of the hydrothermal reservoir and the activity of the magmatic system. Compositional data of the thermal water samples were integrated in a hydrological conceptual model, which describes the formation of the vent fluid by mixing of seawater, seawater concentrated by boiling, and a deep, highly-saline end-member, whose composition is regulated by water-rock interactions at relatively high temperature and shows clear clues of magmatic-related inputs. The chemical composition of concentrated seawater was assumed to be represented by that of the water sample having the highest Mg content. The composition of the deep end-member was instead calculated by extrapolation assuming a zero-Mg end-member. The Na–K–Ca geothermometer, when applied to the thermal end-member composition, indicated an equilibrium temperature of approximately 300 °C, a temperature in agreement with the results obtained by gas-geothermometry.
    Description: Published
    Description: 246-254
    Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Description: JCR Journal
    Description: reserved
    Keywords: low-pH waters; shallow submarine hydrothermal springs; Panarea Island ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 19
    Publication Date: 2021-05-17
    Description: 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.
    Description: Published
    Description: 276-286
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: JCR Journal
    Description: reserved
    Keywords: 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 20
    Publication Date: 2021-06-16
    Description: In this paper we present the results of preliminary geomorphic and trenching investigations along the Kahrizak fault. This fault is located south of the highly populated metropolis of Tehran and represents one of the main structures in the area containing important seismic potential. The Kahrizak fault has a very clear expression at the surface where it forms a prominent 35-km-long, 15-m-high scarp on Holocene alluvial deposits. The fault strikes N70°-80°W and dips to the north. Movement is prevalently right-lateral with the northern side of the fault up. Trench excavations exposed a sequence of weathered, massive, alluvial deposits which are dated, by means of radiometric methods, to the Holocene. In the trenches the sequence is intensely deformed by north-dipping, high- and low-angle faults within a 30-m-wide zone. On the basis of stratigraphic and structural relations, some evidence for individual Holocene earthquakes is found; however, we were not able to reconstruct the seismic history of the fault nor to evaluate the size of deformation produced by each event. Because of the possible ~10 m offset of ancient linear hydraulic artifacts (qanáts), that cross the fault, we hypothesize that the most recent event may have occurred in historical times (more recent than 5000 yr B.P.) and it may be one of those reported in this area by the current catalogues of seismicity. Based on these preliminary investigations we estimate an elapsed time between 5000 and 800 years, a maximum slip per event dmax of ~10 m, a minimum Holocene vertical slip rate of ~1 mm/yr versus a horizontal slip rate of ~3.5 mm/yr, a maximum of ~3000 years for the average recurrence time, and an expected Mw = 7.0 to 7.4. These can be considered as a first-hand reference for the activity on this fault.
    Description: Published
    Description: 187-199
    Description: 3.2. Tettonica attiva
    Description: N/A or not JCR
    Description: reserved
    Keywords: Iran ; paleoseismicity ; geomorphology ; seismic hazard assessment ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 21
    Publication Date: 2020-10-29
    Description: We report high-resolution magnetic measurements from two Mediterranean piston cores: LC07 (Sicily Strait) and LC10 (Ionian Sea). Magnetostratigraphic results and δ18O data provide age constraints for core LC07, where we investigate magnetic property variations for two age intervals (0-600 kyr and 660-1020 kyr). For core LC10, rock magnetic parameters appear to be climatically controlled and are used to derive an astronomically tuned age model for the interval between 780 and 1200 kyr. In core LC07, the dominant control on the magnetic properties appears to be glacial-interglacial variations in the concentration of biogenic magnetite. In addition, an increased contribution from high coercivity minerals (e.g. hematite and/or goethite) probably reflects an enhanced eolian input during glacial periods. Climatic control of magnetotactic bacterial populations has been previously suggested in other environments, but this is the first such report from the Mediterranean. In contrast, the rock magnetic response to Quaternary climatic variability in core LC10 seems to be better expressed by variations in the concentration of high coercivity magnetic minerals. The contrast between a dominantly detrital/eolian flux and a dominantly biogenic flux at the same time for the two Mediterranean settings might relate to the presence of an active current regime in the Sicily Strait, which might decrease delivery of an eolian component to the seafloor compared to the deep Ionian Sea.
    Description: Published
    Description: 195-209
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: reserved
    Keywords: environmental magnetism ; biogenic magnetite ; eolian dust ; glacial-interglacial cycles ; Mediterranean Sea ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 22
    Publication Date: 2020-11-17
    Description: 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.
    Description: Published
    Description: 161-169
    Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Description: JCR Journal
    Description: reserved
    Keywords: Scientific borehole ; Volcanic rocks ; Physical properties ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
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  • 23
    Publication Date: 2020-11-16
    Description: 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.
    Description: Published
    Description: 153-160
    Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Description: JCR Journal
    Description: reserved
    Keywords: 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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  • 24
    Publication Date: 2020-11-17
    Description: 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.
    Description: Published
    Description: 667-674
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: JCR Journal
    Description: reserved
    Keywords: 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 25
    Publication Date: 2021-06-16
    Description: Assessing the residence times of phonolite magmas in the shallow crust contributes to the understanding of explosive volcanic systems. Estimations of that by dating the residence time of a mineral in a melt was difficult in the past, because e.g. of the lack of evidence for the co-genetic character of the crystals dated. Here we present an estimate for the residence time of a phonolite magma feeding the Pomici di Mercato Plinian eruption (8890±90 cal years BP) of Mt. Somma-Vesuvius (Southern Italy), employing U–Th disequilibrium dating of unzoned Ca-rich phenocrystic magmatic garnets. Based on combined textural, geochemical, and Sr- O isotope evidence, these garnets can be identified as co-genetic with their host phonolites. Furthermore, experimental and petrological data suggest that Ca-garnets can be a liquidus phase in highly differentiated phonolite magmas of Mercato. A whole-rock–glass–garnet U–Th isochron gives a crystallisation age for the Ca-rich garnets of 14,400±1100 a (2σ). This implies a Ca-garnet residence time of 5510±1100 years (2σ) in the Mercato phonolite melt prior to eruption and provides one of the first robust estimates of how long explosive phonolite magma has resided in the shallow crust before eruption. Calculations of magma cooling rates and settling velocities of the Ca-garnets confirm that garnet-bearing phonolite can remain liquid and the garnets remain suspended in a magma chamber for as long as 5510 years before the time of eruption. Processes which may have disturbed the U–Th isotope systematic of the samples, such as assimilation, recharge or surface alteration can be ruled out.
    Description: Published
    Description: 293-301
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Uranium ; Thorium ; U–Th isotopes ; Somma-Vesuvius ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
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  • 26
    Publication Date: 2017-04-04
    Description: We report high-resolution paleomagnetic records obtained from six piston cores recovered on the continental rise of theWilkes Land Basin (WLB), East Antarctica, in the frame of the Italian/Australian Wilkes Land Glacial History (WEGA) project. The studied cores, with a length of ca. 4m each, were collected from the gentle and steep sides of sedimentary ridges present in the lower part of the continental rise, and consist of very fine-grained sediments. Paleomagnetic measurements were carried out on u-channel samples. Apart from a low-coercivity magnetic overprint, removed after the first steps of alternating field demagnetization, each core is characterized by a well defined characteristic remanent magnetization. Paleomagnetic inclinations fluctuate around the expected value (of ca. −77◦) for such high latitude sites and always indicate normal magnetic polarity. Short period oscillations to anomalously shallow paleomagnetic inclinations (up to −20◦) were identified at different levels of the sampled sequences; positive (reverse) inclination values were however not observed. Specific rock magnetic measurements indicate a substantial homogeneity of the magnetic mineralogy in the sampled sequences. For each core we reconstructed curves of relative paleointensity (RPI, as computed by NRM20mT/κ and NRM20mT/ARM20mT) variation of the geomagnetic field. An original age modelwas established by tuning the individual RPI curves with the available global and regional reference RPI stacks. Paleomagnetic results, supported by other limited bio- and chronostratigraphic constraints, establish that all the cores are Late Pleistocene in age: two provide an expanded record of the last ca. 30 ka (PC18 and PC19), three span the last ca. 100, 200 and 300 ka (respectively, PC25, PC27 and PC26), and one reaches back to ca. 780 ka (PC20), approaching the Brunhes–Matuyama transition. Thus, the WEGA paleomagnetic record provides the first experimental data documenting the dynamics and amplitude of the geomagnetic field variations at high southern latitudes during the Brunhes Chron. The individual normalized RPI records were merged in aWEGARPI stacking curve spanning the last 300 kyr. The comparison of theWEGARPI individual and stacked curves with the global references RPI stacks shows that geomagnetic paleointensity variations, with periods longer than a few to tens kyr depending on the sedimentation rate, can be safely recognized in this sector of the peri-Antarctic margins. Furthermore, the stacking of the individual ChRM inclination records indicates that the recurrent swings to shallow paleomagnetic inclinations may be correlated to the main known geomagnetic excursions of the Brunhes Chron, supporting the validity of the age models. The reconstructed average sediment accumulation rates for the individual cores range from 0.6 to 19 cm/ka and are compatible with their position within the WLB, with the lowest rates found close to the ridge of the sedimentary drifts. Moreover, the high-resolution age models obtained in this study provide original constraints to assess chronology, rates and amplitudes of the climatic and environmental processes affecting this key area of the peri-Antarctic margins during the Late Pleistocene.
    Description: Published
    Description: 223-242
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: Paleomagnetism; Relative paleointensity; Geomagnetic excursions; Antarctica; Brunhes Chron ; 04. Solid Earth::04.05. Geomagnetism::04.05.02. Geomagnetic field variations and reversals ; 04. Solid Earth::04.05. Geomagnetism::04.05.05. Main geomagnetic field
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  • 27
    Publication Date: 2017-04-04
    Description: Major and trace element and Sr–Nd–Hf–Pb isotopic data for the most primitive Tertiary lavas from the Veneto region (South-Eastern Alps, Italy) show the typical features of HIMU hotspot volcanism, variably diluted by a depleted asthenospheric mantle component (87Sr/86Sri=0.70306–0.70378; "Ndi=+3.9 to +6.8; "Hfi=+6.4 to +8.1, 206Pb/204Pbi=18.786–19.574). P-wave seismic tomography of the mantle below the Veneto region shows the presence of low-velocity anomalies at depth, which is consistent with possible upwellings of plume material. Between the depths of 100–250 km the velocity anomalies are approximately 2–2.5% slower than average, implying a temperature excess of about 220–280 K, in agreement with estimates for other mantle plumes in the world. In this context, the Veneto volcanics may represent the shallow expression of a mantle upflow. The presence of a HIMU-DM component in a collision environment has significant geodynamic implications. Slab detachment and ensuing rise of deep mantle material into the lithospheric gap is proposed to be a viable mechanism of hotspot magmatism in a subduction zone setting.
    Description: Published
    Description: 563–590
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: trace-element ; isotopic composition ; alkali basalts ; central-Europe ; slab break-off ; plume ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
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  • 28
    Publication Date: 2017-04-04
    Description: One of the most challenging issues about the Tertiary–Quaternary alkaline magmatism spreading across the Euro-Mediterranean region is the assessment of both the nature of its mantle source and the mechanism responsible for the common HIMU-like (High μ=high 238U/204Pb) character of erupted lavas, enduring over about 100 million years in diverse tectonic environments. In this paper we try to reconcile geochemical and geophysical data through a multidisciplinary investigation on geochemistry, timing and locations of the main Na-rich alkaline volcanic centers, seismic tomographic images and plate kinematics. We propose that the common component of the Euro-Mediterranean mantle derives from a contamination episode triggered by the rise of the Central Atlantic Plume (CAP) head. Plate reconstruction shows that at late Cretaceous- Paleocene time the oldest magmatic centers of the Euro-Mediterranean region were located more than 2000 km SW of their present day position, in proximity of the CAP hot spot location, where seismic tomography detects a broad low seismic velocity region in the lower mantle. The northeastward migration of the Eurasian and African plates could have involved also part of the CAP contaminated mantle, which moved in the same direction being coupled to the lithospheric plates, thus explaining the presence of geochemically-uniform material spread in the sub-lithospheric Euro-Mediterranean mantle. During the Tertiary, regional-scale convection and related processes such as rifting, back-arc spreading, slab detachment/windows, may have favored upwelling and partial melting of the frayed plume head material via adiabatic decompression, shaping the spatial and temporal distribution of HIMU-like volcanics. The growing supply of subducted lithosphere may explain as well the increase of crustal isotopic signatures of alkaline magmas with time. In our opinion, the Euro-Mediterranean upper mantle contamination can be eventually related to a global event occurred during the Cretaceous as a consequence of a mantle avalanche caused by the Tethys closure.
    Description: MIUR 2005-2007, prot. n. 2005055415_002, Poli G.
    Description: Published
    Description: 15–27
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: partially_open
    Keywords: Cenozoic HIMU–OIB volcanism ; Euro-Mediterranean mantle ; geochemistry ; mantle tomography ; plate kinematics ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
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  • 29
    Publication Date: 2017-04-04
    Description: The controversial relationship between the orogenic segments of the Western Alps and the Northern Apennines is here explored integrating recently published 3D tomographic models of subduction with new and re-interpreted geological observations from the eclogitic domain of the Voltri Massif (Ligurian Alps, Italy), where the two belts joint each other. The Voltri Massif is here described as an extensional domain accommodating the opposing outward migration of the Alpine and Apennine thrust fronts, since about 30–35 Ma. Using tomographic images of the upper mantle and paleotectonic reconstructions, we propose that this extensional setting represents the surface manifestation of an along strike change in polarity of the subducted oceanic slab whose polarity changed laterally in space and in time. Our tectonic model suggests that the westward shift of the Alpine thrust front from the Oligocene onward was the consequence of the toroidal asthenospheric flow induced by the retreat of the Apenninic slab.
    Description: Published
    Description: 34–50
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: Western Alps ; Northern Apennines ; Voltri Massif ; Tomography ; Kinematic reconstruction ; Extensional detachment ; Toroidal flow ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
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  • 30
    Publication Date: 2017-04-04
    Description: In the present work we investigate the temporal distributions of the geomagnetic jerks occurring in the last three decades of the 20th century using a new method of analysis based on the wavelet transform: the Local Intermittency Measure (LIM). This method, which allows us to single out intermittent structures within a given time series, was applied to geomagnetic monthly means time series of the eastward magnetic field component (Y) of 44 worldwide observatories. We study the bimodal distribution of the jerk occurrence in time for the 1978 and 1991 events and point out a local/regional jerk in South Africa and in the Pacific Ocean which happened around 1986. The worldwide character of the 1999 geomagnetic jerk is also investigated integrating the LIM analysis with the traditional straight-line fit.
    Description: Published
    Description: 261-272
    Description: 3.4. Geomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: geomagnetic jerk ; Local Intermittency Measure ; geomagnetic secular variation ; wavelet analysis ; 04. Solid Earth::04.05. Geomagnetism::04.05.02. Geomagnetic field variations and reversals
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  • 31
    Publication Date: 2017-04-04
    Description: Reaction path modelling, coupled with preparatory inverse modelling, was applied to test this model's ability to reproduce the wide compositional range of ground waters circulating in a restricted area in Piedmont, Italy. This approach is based on the assumption that the chemistry of groundwater evolves through a series of partial equilibria with secondary minerals until it reaches its final composition. PHREEQC [Parkhurst, D.L., Appelo, C.A.J., 1999. User's guide to PHREEQC-A computer program for speciation, reaction-path, 1D-transport, and inverse geochemical calculations. U.S. Geological Survey Water-Resources Investigations Report, pp. 99-4259] and EQ3/6 [Wolery, T.J., Daveler, S.A., 1992. EQ6, A Computer Program for Reaction Path Modeling of Aqueous Geochemical Systems: Theoretical Manual, User's Guide and Related Documentation (version 7.0). Report UCRl-MA-110662 PT IV. Lawrence Livermore National Laboratory, Livermore, California] software packages were used to effect simulations. Reaction-path modelling was performed in time mode, taking into account the different rates of dissolution of each dissolving mineral. Data from literature regarding the kinetic parameters of dissolving minerals and the mineralogical composition of the host-rock were used. The results of the reaction-path modelling show that the composition of the analysed water samples was adequately reproduced, notwithstanding the hydrogeological complexity of the studied area. Modelling results provided very different water compositions as an effect of the chemical maturity, the physico-chemical parameters ( fCO2, fO2, and temperature) and the variable amounts of gypsum among dissolving rock-forming minerals, which occur in Miocene levels of the sedimentary sequence. Further variability is related to the occasional contribution of brackish waters trapped in euxinic marly sediments, locally sealed by overlying clays, that have assumed an artesian character. The composition of some of the water samples can only be predicted by simulation runs performed at a temperature higher than that of the outlet (40 °C). These warm waters probably circulate in a restricted area near the town of Nizza Monferrato. The same area has recently been affected by moderate seismicity, which has been accompanied by changes in either the temperature or chemistry, or both, of the ground waters. The changes recorded, interpreted as having been triggered by variations in the local/regional stress load and/or seismic activity, have to be ascribed to the vertical heterogeneity of the aquifers, where waters of different temperature, salinity and chemical composition circulate and occasionally mix.
    Description: Municipality of Nizza Monferrato (Asti, Italy) and the Regional Administration of Regione Piemonte (Italy)
    Description: Published
    Description: 14-39
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: reserved
    Keywords: Reaction-path modelling ; EQ3/6 ; Inverse modelling ; Tertiary Piedmont Basin ; Monferrato ; Seismicity ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters
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  • 32
    Publication Date: 2017-04-04
    Description: New systematic oblique ionospheric radio sounding measurements over Central Europe, concerning the radio links between Inskip (UK, 53.51N, 2.51W) and Rome (Italy, 41.81N, 12.51E) and between Inskip and Chania (Greece, 35.71N, 24.01E), have been performed since November 2003. Different long-term (i.e. monthly median) ionospheric predictions and nowcasting techniques have been applied and compared with the oblique-incidence radio sounding measurements. The MUF (basic maximum usable frequency) measurements observed during the early part of the experiment have been used to compare the performances of different methods. The preliminary analysis has shown good performances for the long-term prediction models, in particular in winter months for ICEPAC (ionospheric communications enhanced profile analysis and circuit) and in equinox/summer months for ASAPS (advanced stand-alone prediction system) and SIRM&LKW (simplified ionospheric regional model & lockwood). The nowcasting methods SIRMUP&LKW (SIRM updating method & lockwood) and ISWIRM (instantaneous space weighted ionospheric regional model) reveal good results for moderate and disturbed geomagnetic conditions when compared with the long-term prediction methods.
    Description: Published
    Description: 854-865
    Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
    Description: JCR Journal
    Description: reserved
    Keywords: Ionosphere ; Monthly median models ; Nowcasting models ; Oblique radio sounding ; 01. Atmosphere::01.02. Ionosphere::01.02.03. Forecasts ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 33
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    Elsevier
    In:  Tanguy, J.C., Principe, C., Arrighi, S., 2005. Comment on “Historical measurements of the Earth’s magnetic field compared with remanence directions from lava flows in Italy over the last four centuries”. In: Lanza, R., Meloni, A., Tema, E. (Eds.), Phys Earth Planet. Inter. 152, 116–120.
    Publication Date: 2017-04-04
    Description: A comparison of the geomagnetic directions derived from lava flows of Italian volcanoes with those derived from direct historical measurements of the Earth’s magnetic field (Lanza et al., 2005) yielded two main results: (1) The general agreement between the two data sets already noted by previous authors (Rolph et al., 1987; Incoronato et al., 2002; Tanguy et al., 2003) was better substantiated. (2) The thermal remanent magnetization (TRM) direction of most flows was shown to deviate from the corresponding historical direction by a small angle θ. In most cases, this angle was larger than the experimental error on the TRM direction as given by the α95 semi-angle of confidence of Fisher’s statistics, i.e. θ 〉 α95. The conclusion drawn from these results was straightforward: a better understanding of the causes of the TRM deviation is required if we are to fully exploit the precision of TRM data from Italian volcanoes when their α95 value is less than 2.5–3.0◦.
    Description: Published
    Description: 121-124
    Description: 1.6. Osservazioni di geomagnetismo
    Description: 2.6. TTC - Laboratorio di gravimetria, magnetismo ed elettromagnetismo in aree attive
    Description: 3.4. Geomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: Secular variation ; Historical magnetic measurements ; Thermal remanent magnetization ; Volcanic rocks ; 04. Solid Earth::04.05. Geomagnetism::04.05.02. Geomagnetic field variations and reversals ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
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  • 34
    Publication Date: 2017-04-04
    Description: The age of spreading of the Liguro–Provençal Basin is still poorly constrained due to the lack of boreholes penetrating the whole sedimentary sequence above the oceanic crust and the lack of a clear magnetic anomaly pattern. In the past, a consensus developed over a fast (20.5–19 Ma) spreading event, relying on old paleomagnetic data from Oligo–Miocene Sardinian volcanics showing a drift-related 30° counterclockwise (CCW) rotation. Here we report new paleomagnetic data from a 10-mthick lower–middle Miocene marine sedimentary sequence from southwestern Sardinia. Ar/Ar dating of two volcanoclastic levels in the lower part of the sequence yields ages of 18.94±0.13 and 19.20±0.12 Ma (lower–mid Burdigalian). Sedimentary strata below the upper volcanic level document a 23.3±4.6° CCW rotation with respect to Europe, while younger strata rapidly evolve to null rotation values. A recent magnetic overprint can be excluded by several lines of evidence, particularly by the significant difference between the in situ paleomagnetic and geocentric axial dipole (GAD) field directions. In both the rotated and unrotated part of the section, only normal polarity directions were obtained. As the global magnetic polarity time scale (MPTS) documents several geomagnetic reversals in the Burdigalian, a continuous sedimentary record would imply that (unrealistically) the whole documented rotation occurred in few thousands years only. We conclude that the section contains one (or more) hiatus(es), and that the minimum age of the unrotated sediments above the volcanic levels is unconstrained. Typical back-arc basin spreading rates translate to a duration ≥3 Ma for the opening of the Liguro–Provençal Basin. Thus, spreading and rotation of Corsica–Sardinia ended no earlier than 16 Ma (early Langhian). A 16–19 Ma, spreading is corroborated by other evidences, such as the age of the breakup unconformity in Sardinia, the age of igneous rocks dredged west of Corsica, the heat flow in the Liguro–Provençal Basin, and recent paleomagnetic data from Sardinian sediments and volcanics. Since Corsica was still rotating/drifting eastward at 16 Ma, it presumably induced significant shortening to the east, in the Apennine belt. Therefore, the lower Miocene extensional basins in the northern Tyrrhenian Sea and margins can be interpreted as synorogenic "intra-wedge" basins due to the thickening and collapse of the northern Apennine wedge.
    Description: Published
    Description: 231-251
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: Paleomagnetism ; Corsica-Sardinia ; Liguro-Provençal Basin ; Back-arc spreading ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
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  • 35
    Publication Date: 2017-04-04
    Description: The GEOSTAR is a technological and scientific project aimed at the realisation of an autonomous benthic observatory able to perform long-term, continuous and integrated geophysical and environmental measurements in deep seafloors. The observatory is conceived to be a node of existing and future geophysical monitoring networks, making possible their extension offshore. The GEOSTAR observatory prototype hosts sensors for seismic, geomagnetic, gravimetric, geochemical and oceanographic researches up to abyssal depths (4000 m). The first 1-year scientific mission is foreseen within the end of the millennium in the abyssal plain (3400 m) of the Southern Tyrrhenian Sea, where key information about the geodynamics and oceanography of the whole Mediterranean basin can be acquired.
    Description: Published
    Description: 175-183
    Description: JCR Journal
    Description: reserved
    Keywords: Seafloor observatories ; Geophysics ; Water geochemistry ; Physical oceanography ; 03. Hydrosphere::03.01. General::03.01.08. Instruments and techniques ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 03. Hydrosphere::03.02. Hydrology::03.02.07. Instruments and techniques
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  • 36
    Publication Date: 2017-04-03
    Description: Lecter section of Physics of the Earth and Planetary Interiors 97 (1996)
    Description: Standard ways of building regional models of the geomagnetic field fail when one wishes to model secular variation (SV). The reason for this is that the SV is mainly a large-scale feature, while regional modelling is most appropriate for characterizing small-scale features. The new idea presented in this note consists in reducing this effect by requiring that the spatial derivatives of the SV produced by the regional model fit the values given by global (and smoother) models such as the international geomagnetic reference field.
    Description: Published
    Description: 15-21
    Description: N/A or not JCR
    Description: reserved
    Keywords: geomagnetic regional models ; secular variation ; 04. Solid Earth::04.05. Geomagnetism::04.05.03. Global and regional models ; 05. General::05.01. Computational geophysics::05.01.03. Inverse methods
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  • 37
    Publication Date: 2017-04-04
    Description: Preface to Journal of Atmospheric and Solar-Terrestrial Physics 67 (2005)
    Description: At the beginning of the new millennium, ionospheric physics and its application in new technologies are at a point of significant change and new development. Ionospheric studies in the past found application in the traditional areas of broadcast and terrestrial radio communications. It has become clear, in recent years, that an understanding of the ionosphere, as a part of the upper atmosphere, is central to the design of many modern communication, navigation and positioning systems. An important additional role has also been recognized in the areas of space weather science and services. This issue of the Journal of Atmospheric and Solar-Terrestrial Physics collects selected contributions presented at the Solar-Terrestrial Sciences session ST14 on "Space weather and RF communications: monitoring and modelling" held during the first General Assembly of the European Geosciences Union (Nice, France, 25–30 April 2004).
    Description: Published
    Description: 1053
    Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
    Description: JCR Journal
    Description: reserved
    Keywords: Space weather ; RF communications ; Ionospheric physics ; 01. Atmosphere::01.01. Atmosphere::01.01.04. Processes and Dynamics ; 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation ; 05. General::05.07. Space and Planetary sciences::05.07.02. Space weather
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  • 38
    Publication Date: 2017-04-04
    Description: Inter-laboratory and absolute calibrations of rock magnetic parameters are fundamental for grounding a rock magnetic database and for semi-quantitative estimates about the magnetic mineral assemblage of a natural sample. Even a dimensionless ratio, such as anhysteretic susceptibility normalized by magnetic susceptibility (Ka/K) may be biased by improper calibration of one or both of the two instruments used to measure Ka and K. In addition, the intensity of the anhysteretic remanent magnetization (ARM) of a given sample depends on the experimental process by which the remanence is imparted. We report an inter-laboratory calibration of these two key parameters, using two sets of artificial reference samples: a paramagnetic rare earth salt, Gd2O3 and a commercial "pozzolanico" cement containing oxidized magnetite with grain size of less than 0.1 m according to hysteresis properties. Using Gd2O3 the 10 Kappabridges magnetic susceptibility meters (AGICO KLY-2 or KLY-3 models) tested prove to be cross-calibrated to within 1%. On the other hand, Kappabridges provide a low-field susceptibility value that is ca. 6% lower than the tabulated value for Gd2O3, while average high-field susceptibility values measured on a range of instruments are indistinguishable from the tabulated value. Therefore, we suggest that Kappabridge values should be multiplied by 1.06 to achieve absolute calibration. Bartington Instruments magnetic susceptibility meters with MS2B sensors produce values that are 2–13% lower than Kappabridge values, with a strong dependence on sample centering within the sensor. The Ka/K ratio of ca. 11, originally obtained on discrete cement samples with a 2G Enterprises superconducting rock magnetometer and a KLY-2, is consistent with reference parameters for magnetites of grain size 〈0.1 m. On the other hand, Ka values from a 2G Enterprises magnetometer and K values from a Bartington Instruments MS2C loop sensor for u-channel and discrete cement samples, will produce average Ka/K values that are unrealistically high if not properly corrected for the nominal volume detected by the sensors for these instruments. Inter-laboratory measurements of K and Ka for standard paleomagnetic plastic cubes filled with cement indicate remarkable differences in the intensity of the newly produced ARMs (with a standard deviation of ca. 21%), that are significantly larger than the differences observed from the calibration of the different magnetometers employed in each laboratory. Differences in the alternating field decay rate are likely the major source of these variations, but cannot account for all the observed variability. With such large variations in experimental conditions, classical interpretation of a "King plot" of Ka versus K would imply significant differences in the determination of grain size of magnetite particles on the same material.
    Description: Published
    Description: 25-38
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: Rock magnetism ; Magnetic susceptibility ; Anhysteretic remanent magnetization ; Calibration ; Instrumentation ; Relative ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.08. Instruments and techniques
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  • 39
    Publication Date: 2017-04-04
    Description: We report on new paleomagnetic results obtained from 27 sites sampled in the Plio-Pleistocene sequences at the external front of the central-northern Apennines. Previous analyses of Miocene (Messinian) sediments indicated that the present shape of the northern Apenninic arc is due to the oroclinal bending of an originally straight belt oriented around N320° and that vertical axis rotations accompanied the migration of the thrust fronts toward the Adriatic foreland [F. Speranza et al., J. Geophys. Res. 102 (1997) 3153-3166]. We tried to provide new paleomagnetic constraints for the timing and rates of the oroclinal bending process during the Pliocene and the Pleistocene. The results suggest that CCW rotations observed in the northern part of the studied area are possibly younger than 3 Ma. No regional rotation is recorded in the Pliocene and Pleistocene sediments from the southern part of the study area, analogously to the Messinian sediments of the 'Acquasanta' domain of Speranza et al. [F. Speranza et al., J. Geophys. Res. 102 (1997) 3153-3166]. A local significant CCW rotation (23° ± 10°) is identified in the Early Pleistocene sediments that crop out along the Adriatic coast between Ascoli and Pescara, indicating differential motion of the thrust sheets. This rotation must be younger than 1.43 Ma.
    Description: Published
    Description: 243-257
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: open
    Keywords: paleomagnetism ; Apennines ; tectonics ; Pliocene ; Pleistocene ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
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  • 40
    Publication Date: 2017-04-04
    Description: The Antarctic region has profoundly affected the global climates of the past 50 million years, influencing sea levels, atmospheric composition and dynamics, and ocean circulation. A greater understanding of this region and the Antarctic cryosphere is crucial to a broader understanding of the global climates and palaeoceanography at all scales. Much of the information obtained during the last two decades derives from studies of sedimentary sequences drilled in and around Antarctica. Eight Ocean Drilling Program (ODP) legs have contributed significantly to the understanding of this evolution. These legs include Leg 113 in the Weddell Sea (Barker et al., 1988, 1990), Leg 114 in the Subantarctic South Atlantic (Ciesielski et al., 1988, 1991), Leg 119 in Prydz Bay and on Kerguelen Plateau (Barron et al., 1989, 1991), Leg 120 on Kerguelen Plateau (Schlich et al., 1989; Wise et al., 1992), Leg 177 in the southeast Atlantic sector of the Southern Ocean (Gersonde et al., 1999), Leg 178 on the Antarctic Peninsula (Barker et al., 2002), Leg 188 in Prydz Bay (O’Brien et al., 2001), and Leg 189 in the Tasmanian region (Exon et al., 2001). More recently, a series of three holes were drilled in McMurdo Sound, Ross Sea, as part of the Cape Roberts Project (CRP; Cape Roberts Science Team, 1998 1999, 2000; Hambrey et al., 1998; Barrett et al., 2000, 2001). In spite of these efforts, which have significantly advanced our understanding of the Cenozoic tectonics and palaeoenvironments of the Antarctic region, important questions and problems remain unresolved. Chief amongst these are the timing of the onset of the East Antarctic Ice Sheet (EAIS), the causes of the cooling events at around 24 and 14 Ma, and the warming events of the mid-Pliocene and Marine Isotope Stages 31 (1.07 Ma) and 11 (0.36 Ma) (Shackleton et al., 1995).
    Description: Published
    Description: 1-9
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: reserved
    Keywords: Antarctic climate evolution ; 03. Hydrosphere::03.01. General::03.01.06. Paleoceanography and paleoclimatology
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  • 41
    Publication Date: 2017-04-04
    Description: Along the southern coast of the Gulf of Corinth, important coastal uplift is illustrated by raised Late-Pleistocene marine platforms. Terrace remnants preserved on the footwall of the Aigion and Eliki Faults were mapped in detail. To derive cumulative uplift rates, the individual terraces were tentatively correlated with the eustatic sea-level curve, constrained by some direct dating of the deposits blanketing the terraces. We obtain uplift rates of 1.05–1.2 mmyr−1 for the Aigion Fault footwall and of 1.0 and 1.25 mmyr−1 for the East and West Eliki Fault footwalls respectively. A forward modelling procedure was adopted to fit the best-preserved terrace transects, using a code based on standard dislocation theory and assuming reasonable scenarios of regional uplift. We obtained maximum slip rates consistently in the range of 7–11 mmyr−1 for the West and East Eliki Faults and of 9–11 mmyr−1 for the Aigion Fault.
    Description: Published
    Description: 325-334
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: slip rate ; marine terraces ; modeling ; Corinth Gulf, Greece ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology
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  • 42
    Publication Date: 2017-04-04
    Description: New estimates on the Quaternary slip rate of the active transform margin of North Anatolia are provided. We investigated the area struck by a Mw 7.1 earthquake on the 12th of November 1999 that ruptured the Düzce Fault segment of the North Anatolian Fault. In order to analyze the spectacular tectonically driven cumulative landforms and the drainage pattern settings, we carried out a 1:25,000-scale geological and geomorphological mapping along the fault trace. We reconstruct and describe, as offset geomorphic markers, right-hand stream deflections and fluvial terraces inset into alluvial fan deposits. Radiocarbon dating indicates that ∼100 m stream deflections were built up by the last ∼7000 yrs of fault activity. Conversely, two documented and correlated Late Pleistocene fluvial terraces are horizontally offset by ∼300 and ∼900 m, respectively. These were dated by means of Optically Stimulated Luminescence (OSL) to ∼21 ka BP and 60 ka BP. Assuming a constant rate of deformation for the Düzce Fault, ages and related offsets translate to consistent slip rates that yield an average slip rate of 15.0±3.2 mm/yr for the last 60 ka. Thus, the Düzce Fault importantly contributes to the North Anatolian margin deformation, suggesting a present-day partitioning of displacement rates with the Mudurnu Fault to the south and confirming its important role in the seismic hazard of the area.
    Description: Published
    Description: 538-554
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: Tectonic geomorphology ; Geomorphic markers ; Slip rate ; Strike-slip ; 1999 Düzce earthquake ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
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  • 43
    Publication Date: 2017-04-04
    Description: Invited reply to the Comment on: “Geomorphological, paleontological and 87Sr/86Sr isotope analyses on early Pleistocene paleoshorelines to define the uplift of Central Apennines (Italy)”
    Description: In response to the comment of Cosentino and Fubelli (2007) on the stratigraphy of the Middle Valley of Tiber River basin (MVT) and on the chronological attribution of the uppermost paleoshorelines (UPS), we recall that we performed a detailed sampling campaign to date the youngest marine deposits underlying or laterally related to the UPS, through the 87Sr/86Sr method. Unfortunately, we cannot have taken advantage from the new stratigraphic data of the comment, being that all these data are still unpublished. On the sections presented in the comment, which concern only the southernmost tract of the UPS alignment, we do not know exactly how close these sections are to the UPS and how accurate the stratigraphic relationships are. This is due to the absence in the comment of detailed geographic locations of sections and of any stratigraphic scheme or geological map that might help link the data presented in Mancini et al. (2007) with the new ones. In general, the age of the new proposed sections are considered older (Gelasian) than our age estimate (1.65–1.50 Ma, i.e. late Santernian) for the UPS.
    Description: Published
    Description: 165-167
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: Early Pleistocene ; shoreline ; uplift ; Apennines ; Sr isotope ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous
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  • 44
    Publication Date: 2017-04-04
    Description: The Cenozoic evolution of the Antarctic cryosphere and fluctuations in its ice sheet cover are considered to be one of the major influences on low- and mid-latitude deep-sea sedimentary records. Long-term Cenozoic trends and short-term climate fluctuations (≤40 ka) alike are inferred to have been driven or modulated by changes in Antarctic ice sheet volume (Kennett, 1977; Imbrie and Imbrie, 1980; Zachos et al., 1997, 2001; Shackleton et al., 1999; Lear et al., 2000; Naish et al., 2001). Similarly, changes in sea level elevations at continental margins are also inferred to result from growth and decay in Antarctic ice sheet volume throughout the Cenozoic (Barrett et al., 1987; Haq et al., 1987). Yet, direct records of the Antarctic cryosphere and its ice sheets are sparse at best, and much of the inference remains untested. Recent efforts have begun to change this, and the last decade has seen several expeditions to the Antarctic and Southern Oceans, which have recovered new high-quality sedimentary core and seismic reflection records of Southern high-latitude Cenozoic ice sheets and climate. These include the Cape Roberts Project (CRP) (Cape Roberts Science Team, 1998; Hambrey et al., 1998; Cape Roberts Science Team, 1999; Barrett et al., 2000; Cape Roberts Science Team, 2000; Barrett et al., 2001; Davey et al., 2001), ODP Leg 177 (Gersonde et al., 1999, 2003), Leg 178 (Barker et al., 1999, 2002), Leg 182 (Feary et al., 2000; Hine et al., 2004), Leg 188 (O’Brien et al., 2001; Cooper et al., 2004), and Leg 189 (Exon et al., 2001, in press), and various RVIB NB Palmer and Polarstern cruises. Recent results from these expeditions were presented at a special session of the EGS–AGU Joint assembly held in Nice, France, in April 2003. The focus of the session was the many orders and scales of variation of Antarctic ice sheets and climate from Antarctic and sub-Antarctic records derived from outcrop studies, deep sea and continental margin drilling, and seismic reflection investigations. The session also included new modelling results utilizing new data from these recent expeditions and preliminary results of geophysical surveys defining sub-ice shelf and sea ice sedimentary basins identified as drilling targets in the near future under the ANDRILL program (Harwood et al., 2002; Florindo et al., 2003a).
    Description: Published
    Description: 1-7
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: reserved
    Keywords: Antarctic climate evolution ; 03. Hydrosphere::03.01. General::03.01.06. Paleoceanography and paleoclimatology
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  • 45
    Publication Date: 2017-04-03
    Description: Ocean Drilling Program holes 744Aand 748B represent key sections for calibration of Southern Ocean Eocene-Oligocene biostratigraphic zonations. Sites 744 and 748 were above the carbonate compensation depth throughout this time interval and contain good planktonic foraminiferal, calcareous nannofossil, and diatom biostratigraphic records. In particular, the Southern Ocean diatom biostratigraphic zonation for the Oligocene critically hinges on calibration of these two holes. Previous low-resolution magnetostratigraphic studies at these sites were hampered by limited sampling and technical difficulties, which prompted our high-resolution reinvestigation of the magnetostratigraphy. Magnetic polarity zonations for holes 744Aand 748B were constructed after inspection of vector component plots at 1-cm stratigraphic intervals from continuous u-channel measurements. The magnetizations are generally stable and a robust polarity stratigraphy has been obtained for both holes. The increased resolution of our study and identification of persistent secondary overprints, which were not recognised in previous studies, suggests that the previously published interpretations need to be revised. Our magnetostratigraphic interpretations for both holes are constrained by foraminiferal and calcareous nannofossil datums, as well as by Sr isotope ages. We have calibrated four diatom datums, which are synchronous at the two studied sites, to the geomagnetic polarity timescale, including the first occurrence (FO) of Lisitzinia ornata (27.8 Ma), the FO of Rocella vigilans var. B (27.8 Ma), the FO of Cavitatus jouseanus (30.9 Ma) and the FO of Rhizosolenia oligocaenica (33.8 Ma). The synchroneity of these datums suggests that diatom biostratigraphy has considerable potential for Palaeogene biostratigraphic correlation in the Southern Ocean. Although the ages of some datums are obscured by an unconformity in Hole 744A, our age model from Hole 748B suggests age estimates for the last common occurrence of Rocella vigilans var. A(~29.0 Ma), the FO of Rocella vigilans var. A(30.0 Ma) and the FO of Rhizosolenia antarctica (33.2 Ma). It should also be noted that the last occurrence of the calcareous nannofossil Chiasmolithus altus occurs in Chron C8r rather than C8n in our revised magnetostratigraphic interpretation, which indicates that this datum is not diachronous between low and mid latitudes as had previously been suggested. Significant unconformities are documented in both holes, in the middle Oligocene and in the middle late Oligocene, respectively, which probably resulted from periods of enhanced circumpolar deep-water circulation.
    Description: Published
    Description: 145-168
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: Eocene ; Oligocene ; Ocean Drilling Program ; holes 744A and 748B ; Kerguelen Plateau ; Antarctica ; magnetostratigraphy ; biostratigraphy ; diatoms ; foraminifera ; calcareous nannofossils ; 03. Hydrosphere::03.01. General::03.01.06. Paleoceanography and paleoclimatology ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 46
    Publication Date: 2017-04-04
    Description: We present the velocity field of the Italian area derived from continuous GPS observations from 2003 to 2007. The GPS sites were installed by different institutions and for different purposes; they cover the whole country with a mean inter-site distance of about 60 km and provide a valuable source of data to map the present day kinematics of the region. The absolute ITRF2005 rotation poles and rates of Eurasia, Africa and Adriatic plates are estimated, to study the kinematics along their boundaries in the Apennines belt. The Corsica–Sardinia block, coherently moving as the Eurasia plate, is used as reference of the upper plate for the Apennines subduction zone.We apply a simple kinematic model to estimate the rates and spatial pattern of the subduction along the Apennines. We identify at least four different, independently moving, lower plates, i.e., the Adriatic (diverging and internally segmented), Ionian, Sicily and Africa (converging) plates with different subduction rates. The conservative estimates of the subduction rate are ~5 mm/yr in the Calabrian Arc, ~1.5 mm/yr in Sicily, and ~0.9 mm/yr in the northern Apennines. This variegate mixture of behaviors seems to reflect the variable lithospheric thickness and composition of the lower plates inherited from the Mesozoic rifting. An unexpected along strike contraction is observed along the western side of the central-northern Apennines. Velocities are estimated both relative to Eurasia, and relative to the deep and shallow hotspot reference frames (HSRF). The hotspot representation seems more coherent with the geophysical and geological constraints along the subduction system, in which the Adriatic and Ionian plates move SW-ward and their deeper slab portions provide an obstacle to the opposite relative mantle flow. All these patterns better reconcile if the subduction process is conceived as a passive feature controlled by the far field plate velocities and the relative “eastward” mantle flow acting on a disrupted slab.
    Description: Published
    Description: 163-174
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: GPS ; ITRF2005 ; Adriatic ; Eurasia ; Africa ; Euler poles ; Apennines ; slab kinematics ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 47
    Publication Date: 2017-04-04
    Description: 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.
    Description: Published
    Description: 79-95
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 48
    Publication Date: 2017-04-04
    Description: In this work, we report the results of an integrated approach using both seismological and geodetic data provided by the INGV-CT (Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Catania) Stromboli volcano monitoring systems, in order to improve the knowledge of its plumbing system. In particular, we investigated the relationships between the June 1999 seismic swarm, occurring in the area of Stromboli, and the possible activation of the NE–SW oriented volcano-tectonic structure. We analyzed this seismic swarm proposing new locations and a morphological analysis of the waveforms. This approach allowed us to demonstrate that there are relationships between the tectonic activity near Stromboli and the rising of magma. This evidence supports the hypothesis that during the 1999 swarm an intrusive process started from a crustal level where earthquakes were located (about 10–15 km b.s.l.). As already testified by other similar episodes (deformation anomaly recorded between December 1994 and March 1995 after the November 1994 swarm), months after the 1999 seismic activity, the tiltmeters and the GPS permanent stations deployed in Stromboli, showed slow variations over three months (May–July 2000). We performed an analytical inversion of these geodetic observations and found that the modelled sources are characterized by NE–SW trend, compatible with the regional faults cutting the volcano. The modelled sources could represent the rising pathway connecting the “deep” plumbing system (about 10–15 km b.s.l.) to the “shallow” one located in the body of the Stromboli volcano (about 500 m a.s.l.). These new evidences support the hypothesis of the existence of a simple plumbing system with different levels of magma storage, where batches of magma are periodically pushed up along the main NE–SW tectonic trend.
    Description: Published
    Description: 529-540
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: stromboli ; plumbing system ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 49
    Publication Date: 2017-04-04
    Description: We present a morphological analysis of Nevado de Toluca volcano located 80 km WSW of Mexico City based on digital elevation model study, where slope and aspect maps have been generated and analysed. Aerial photograph and satellite image observations improve the morphological analysis. The synoptic view which is offered by this analysis allowed for recognition and localization of the main volcanic and tectonic features of the area. On the basis of digital elevation model value distribution and surface textures, five morphological domains were defined. The most interesting domain, south of the crater, reflects the occurrence of an ancient complex volcano distinct from the adjacent areas. Interaction between the volcanic and volcano– tectonic evolution and the basement produced the other domains. Single volcanic edifices, like lava domes and scoria cones, and eruptive fractures were recognized. Finally, flank collapse scarps opened to the east and to the north were identified and four relevant morphostructural lineaments and their possible role in the Nevado de Toluca geological and structural evolution are discussed.
    Description: CONACYT J37889-T
    Description: Published
    Description: 47–61
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: JCR Journal
    Description: reserved
    Keywords: Nevado de Toluca ; Mexico ; Volcanic geomorphology ; DEM analysis ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous
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  • 50
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    Elsevier
    In:  Capponi, G., et al., Comment on “Subduction polarity reversal at the junction between the Western Alps and the Northern Apennines, Italy, by G. Vignaroli..., Tectonophysics (2008), doi:10.1016/j.tecto.2008.10.019
    Publication Date: 2017-04-04
    Description: Reply to comment
    Description: We first would like to thank Capponi et al. (2008) for their comments and criticisms on our paper, offering us the opportunity to discuss the data and the model presented in Vignaroli et al. (2008a) and clarify the geological rationale behind our manuscript. Vignaroli et al. (2008a) presented a large-scale reconstruction on the evolution of the Western Alpine-Northern Apennine junction, based on shallow geological information derived from the Northern Apennines, the Western and Ligurian Alps coupled with deep mantle structures from seismic tomography and tectonic reconstructions. The aim of this paper is then to give an alternative, though simplified, tectonic solution to the long-standing debate concerning the polarity of the subduction zone in the central Mediterranean and its linkage with the Alpine orogeny and the formation of the arcs belt. We condensed and simplified the huge wealth of geological information using cross-sections along the three orogenic segments. One of the main points of the paper is that the Voltri Massif of the Ligurian Alps is reinterpreted as an eclogitic-bearing domain exhumed by means of ductile-to-brittle extensional detachment tectonics with a top-to-the-W sense of shear. In this view, the orogenic architecture and evolution of the Ligurian Alps presents affinities (both for geometry and timing of deformation) with the widely accepted extensional structures recognized in the Western Alps, in the Northern Apennines and, in general, in Alpine-type orogenic belts of the Mediterranean. The detailed comment made by Capponi et al. (2008) is indeed centred on the tectonic structure of the Voltri Massif (probably this comment should have been addressed to our companion paper, Vignaroli et al., 2008b, focused on the Voltri Massif structures and available on-line on March 2008). The main point of the comment is that the exhumation of High-Pressure (HP) metamorphic units exposed in the Voltri Massif was produced by thrusts rather than by syn- orogenic extensional detachments. In this reply, we would first like to make some general considerations on the criteria/concepts adopted for the interpretation of the exhumation-related structures and we will then discuss point-by-point the criticism of Capponi et al. (2008).
    Description: In press
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: partially_open
    Keywords: Western Alps ; Northern Apennines ; Voltri Massif ; kinematic reconstruction ; subduction ; extensional detachment ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes
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  • 51
    Publication Date: 2017-04-04
    Description: The Albano Lake is the deepest volcanic lake in Italy (−167 m) and fills the youngest maar of the quiescent Colli Albani volcano. The lake has undergone significant level changes and lahar generating overflows occurred about 5800 yrs B.P. and likely in 398 b.C., when Romans excavated a tunnel drain through the maar wall. Hazardous lake rollovers and CO2 release are still possible because the Albano volcano shows active ground deformation, gas emission and periodic seismic swarms. On November 2005, the first high resolution bathymetric survey of the Albano Lake was performed. Here we present the results provided by a Digital Elevation Model and 2-D and 3-D images of the crater lake floor, which is made by coalescent and partly overlapping craters and wide flat surfaces separated by some evident scarps. Submerged shorelines are identified at depths between −20 m and −41 m and indicate the occurrence of significant lake level changes, likely between 7.1 and 4.1 ka. The current lake volume is ~447.5×106 m3 and the total quantity of dissolved CO2 is 6850 t estimated by chemical analyses of samples collected on May 2006. A decrease of nearly one order of magnitude of the CO2 dissolved in the lake water below −120 m, observed from December 1997 to May 2006 (from 4190 to 465 t respectively), has been attributed to lake water overturn. The observed oscillations of the dissolved CO2 concentrations justify the efforts of monitoring the chemical and physical characteristics of the lake. At present the quantity of dissolved CO2 is very far from saturation and Nyostype events cannot presently occur.
    Description: DPC-INGV Project V3_1
    Description: Published
    Description: 258–268
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Albano maar ; lake bathymetry ; geochemistry ; crater lake hazard ; 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::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 52
    Publication Date: 2017-04-04
    Description: The Colfiorito Mw 6.0 (September 26, 1997, 09:40 UTC) and the Sellano Mw 5.6 (October 14, 1997) normalfaulting earthquakes are the two strongest events of the 1997–1998 Umbria–Marche seismic sequence (central Italy). They provided accelerograms recorded at epicentral distances within nearly two fault lengths. Previous studies on these events revealed clear evidence of unilateral rupture propagation and directivity effects on the source time functions.We developed an approximate procedure to correct the observed peak ground motion for the site effects, and we found a systematic increase of peak ground acceleration (PGA) and peak ground velocity (PGV) at sites located in the direction of the rupture propagation respect to the stations located to the backward. In particularwe showed that, for the Colfiorito earthquake, the average PGV at the north-west sites is 2.8 times larger than the PGV at south-east sites (2.1 for PGA); an opposite behaviour is found during the Sellano earthquake, with an amplification factor of about 1.9 for PGV (1.5 for PGA) recorded at south-east sites respect to the north-west stations.We explained these behaviours in terms of directivity effect, by comparing recorded ground accelerations with synthetics simulated by a deterministic–stochastic technique. This method computes high-frequency ground motions (fN0.5 Hz) from extended faults, generalizing the point-source stochastic method to capture the essence of near-source effects. The synthetic PGAs decrease with distance in agreement with the ground-motion empirical predictive model available for the area and describe the azimuthal variation of recorded data in terms of source effects.
    Description: GNDT-INGV project 2000-2003
    Description: In press
    Description: 3.1. Fisica dei terremoti
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: reserved
    Keywords: directivity ; peak ground motion ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
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  • 53
    Publication Date: 2017-04-04
    Description: The Piànico-Sèllere is a lacustrine succession from northern Italy that records a sequence of climatic transitions across two Pleistocene glacial stages. The intervening interglacial stage is represented by well-preserved varves with calcitic (summer) and clastic (winter) laminae. There is a tight coupling between climate-driven lithologic changes and magnetic susceptibility variations, and stable paleomagnetic components were retrieved from all investigated lithologies including the largely diamagnetic calcite varves. These components were used to delineate a sequence of magnetic polarity reversals that was interpreted as a record of excursions of the Earth’s magnetic field. Comparison of the magnetostratigraphic results with previously published data allows discussion of two possible models which have generated controversy regarding the age of the Piànico Formation. The data indicates that the Piànico Formation magnetostratigraphy correlates to geomagnetic field excursions across the Brunhes/Matuyama transition, and consequently the Piànico interglacial correlates to marine isotope stage 19. This correlation option is substantially consistent with K-Ar radiometric age estimates recently obtained from a tepha layer interbedded in the Piànico Formation. The alternative option, considering the Piànico interglacial correlative to marine isotope stage 11 within the Brunhes Chron as supported by tephrochronological dating reported in the literature, is not supported by the magnetostratigraphic results.
    Description: In press
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: open
    Keywords: Piànico Formation ; Pleistocene ; magnetostratigraphy ; polarity excursions ; Brunhes Chron ; Southern Alps ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 54
    Publication Date: 2017-04-04
    Description: Bathymetric and gravity surveys were carried out from 1988 to 1994, in the Gulf of Naples (Southern Italy) to offshore extend the already existing Bouguer anomaly map. In order to improve the knowledge of the structural setting beneath the active Neapolitan volcanoes (Vesuvio, Campi Flegrei and Ischia), 862 stations were surveyed within the isobath of 400 m; at the same time, and about 2000 on-land gravity values were also collected. A new Bouguer anomaly map spanning the whole volcanic region was drawn from the final data set. Gravity anomalies were referred to the new absolute gravity station in Naples and computed according to 1980 Geodetic Reference System. Finally, a density value of 2200 kg/m3 was used in the computation of the Bouguer and terrain effects. We carried out the inversion of the gravity anomalies adopting a 2.5-D modelling along selected profiles crossing the investigated area. The interpretative models were constrained to data obtained from deep wells and other geophysical investigations. In a previous paper, we investigated in detail the area around the Vesuvio. Here we focus on the Phlegraean Volcanic District (PVD), formed by Campi Flegrei, and the islands of Procida and Ischia. Our interpretation permits to outline two separate caldera-like structures in Campi Flegrei and their rims, mainly in the offshore sector. Moreover, it highlights a sharp separation between the island of Ischia and the rest of the PVD while showing Procida as well integrated, at least from the structural point of view. Ischia appears to be a block delimited all around and stepped by a series of volcano–tectonic structures. Both the qualitative description and the quantitative interpretation of the Bouguer anomaly in the PVD area, together with the comparison with the gravity features of the rest of the Neapolitan area, would suggest that the uprising basement beneath the island of Ischia, inducing most of the gravity signal, could be the carbonate ones. The certainty and the discrimination between a carbonate or lava basement beneath Campi Flegrei is not yet deducible. In addition, for this area, the presence of a magma chamber from the Bouguer anomaly, taking into account the information provided by further geophysical and geochemical researches, was checked. The add-on body improves the model as a whole and doesn't impact on the presence of a residual magma chamber. Finally, the quantitative interpretation also permitted to define the shape and the depth of the 2600 kg/m3 basement (carbonate in places) and of the overlapping denser polygenic layer on which the inferred main structures was drawn.
    Description: Published
    Description: 241–252
    Description: 2.6. TTC - Laboratorio di gravimetria, magnetismo ed elettromagnetismo in aree attive
    Description: JCR Journal
    Description: reserved
    Keywords: gravity ; Bouguer anomaly ; Phlegraean Volcanic District ; Volcanic District ; 04. Solid Earth::04.02. Exploration geophysics::04.02.02. Gravity methods ; 04. Solid Earth::04.03. Geodesy::04.03.04. Gravity anomalies ; 05. General::05.01. Computational geophysics::05.01.03. Inverse methods
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  • 55
    Publication Date: 2017-04-04
    Description: 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.
    Description: Published
    Description: 237–248
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: JCR Journal
    Description: reserved
    Keywords: 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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  • 56
    Publication Date: 2017-04-04
    Description: In this paper we present a collection of good quality shear wave splitting measurements in Southern Italy. In addition to a large amount of previous splitting measurements, we present new data from 15 teleseisms recorded from 2003 to 2006 at the 40 stations of the CAT/SCAN temporary network. These new measurements provide additional constraints on the anisotropic behaviour of the study region and better define the fast directions in the southern part of the Apulian Platform. For our analysis we have selected wellrecorded SKS phases and we have used the method of Silver and Chan to obtain the splitting parameters: the azimuth of the fast polarized shear wave (φ) and delay time (δt). Shear wave splitting results reveal the presence of a strong seismic anisotropy in the subduction system below the region. Three different geological and geodynamic regions are characterized by different anisotropic parameters. The Calabrian Arc domain has fast directions oriented NNE–SSW and the Southern Apennines domain has fast directions oriented NNW–SSE. This rotation of fast axes, following the arcuate shape of the slab, is marked by a lack of resolved measurements which occurs at the transition zone between those two domains. The third domain is identified in the Apulian Platform: here fast directions are oriented almost N–S in the northern part and NNE–SSW to ENE–WSW in the southern one. The large number of splitting parameters evaluated for events coming from different back-azimuth allows us to hypothesize the presence of a depth-dependent anisotropic structure which should be more complicated than a simple 2 layer model below the Southern Apennines and the Calabrian Arc domains and to constrain at 50 km depth the upper limit of the anisotropic layer, at least at the edge of Southern Apennines and Apulian Platform. We interpret the variability in fast directions as related to the fragmented subduction system in the mantle of this region. The trench-parallel φ observed in Calabrian Arc and in Southern Apennines has its main source in the asthenospheric flow below the slab likely due to the pressure induced by the retrograde motion of the slab itself. The pattern of φ in the Apulian Platform does not appear to be the direct result of the rollback motion of the slab, whose influence is limited to about 100 km from the slab. The anisotropy in the Apulian Platform may be related to an asthenospheric flow deflected by the complicated structure of the Adriatic microplate or may also be explained as frozen-in lithospheric anisotropy.
    Description: Published
    Description: 49-67
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: partially_open
    Keywords: Shear wave splitting ; Subduction ; Mantle flow ; Southern Italy ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.01. Earth Interior::04.01.03. Mantle and Core dynamics ; 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::04.07.06. Subduction related processes
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  • 57
    Publication Date: 2017-04-04
    Description: El Chichón crater lake appeared immediately after the 1982 catastrophic eruption in a newly formed, 1-km wide, explosive crater. During the first 2 years after the eruption the lake transformed from hot and ultraacidic caused by dissolution of magmatic gases, to a warm and less acidic lake due to a rapid “magmatic-tohydrothermal transition” — input of hydrothermal fluids and oxidation of H2S to sulfate. Chemical composition of the lake water and other thermal fluids discharging in the crater, stable isotope composition (δD and δ18O) of lake water, gas condensates and thermal waters collected in 1995–2006 were used for the mass-balance calculations (Cl, SO4 and isotopic composition) of the thermal flux from the crater floor. The calculated fluxes of thermal fluid by different mass-balance approaches become of the same order of magnitude as those derived from the energy-budget model if values of 1.9 and 2 mmol/mol are taken for the catchment coefficient and the average H2S concentration in the hydrothermal vapors, respectively. The total heat power from the crater is estimated to be between 35 and 60 MW and the CO2 flux is not higher than 150 t/day or ~200 gm−2 day−1.
    Description: Published
    Description: 472-481
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: JCR Journal
    Description: reserved
    Keywords: El Chichón ; crater lake ; mass-energy budget ; CO2 flux ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 05. General::05.02. Data dissemination::05.02.04. Hydrogeological data
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 58
    Publication Date: 2017-04-04
    Description: We designed a new seismic source model for Italy to be used as an input for country-wide probabilistic seismic hazard assessment (PSHA) in the frame of the compilation of a new national reference map. We started off by reviewing existing models available for Italy and for other European countries, then discussed the main open issues in the current practice of seismogenic zoning. The new model, termed ZS9, is largely based on data collected in the past 10 years, including historical earthquakes and instrumental seismicity, active faults and their seismogenic potential, and seismotectonic evidence from recent earthquakes. This information allowed us to propose new interpretations for poorly understood areas where the new data are in conflict with assumptions made in designing the previous and widely used model ZS4. ZS9 is made out of 36 zones where earthquakes with Mw 〉= 5 are expected. It also assumes that earthquakes with Mw up to 5 may occur anywhere outside the seismogenic zones, although the associated probability is rather low. Special care was taken to ensure that each zone sampled a large enough number of earthquakes so that we could compute reliable earthquake production rates. Although it was drawn following criteria that are standard practice in PSHA, ZS9 is also innovative in that every zone is characterised also by its mean seismogenic depth (the depth of the crustal volume that will presumably release future earthquakes) and predominant focal mechanism (their most likely rupture mechanism). These properties were determined using instrumental data, and only in a limited number of cases we resorted to geologic constraints and expert judgment to cope with lack of data or conflicting indications. These attributes allow ZS9 to be used with more accurate regionalized depth-dependent attenuation relations, and are ultimately expected to increase significantly the reliability of seismic hazard estimates.
    Description: Published
    Description: 85-108
    Description: 3.2. Tettonica attiva
    Description: 4.2. TTC - Scenari e mappe di pericolosità sismica
    Description: JCR Journal
    Description: reserved
    Keywords: Seismotectonics ; Seismic source zone model ; Seismic hazard ; Italy ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 59
    Publication Date: 2017-04-04
    Description: 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.
    Description: Published
    Description: 359-365
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 60
    Publication Date: 2017-04-04
    Description: Disasters from explosive volcanic eruptions are infrequent and experience in emergency planning and mitigation for such events remains limited. The need for urgently developing more robust methods for risk assessment and decision making in volcanic crises has become increasingly apparent as world populations continue to expand in areas of active explosive volcanism. Nowhere is this more challenging than at Vesuvius, Italy, with hundreds of thousands of people living on the flanks of one of the most dangerous volcanoes in the world. We describe how a new paradigm, evidence-based volcanology, has been applied in EXPLORIS to contribute to crisis planning and management for when the volcano enters its next state of unrest, as well as in long-term land-use planning. The analytical approach we adopted enumerates and quantifies all the processes and effects of the eruptive hazards of the volcano known to influence risk, a scientific challenge that combines field data on the vulnerability of the built environment and humans in past volcanic disasters with theoretical research on the state of the volcano, and including evidence from the field on previous eruptions as well as numerical simulation modelling of eruptive processes. Formal probabilistic reasoning under uncertainty and a decision analysis approach have provided the basis for the development of an event tree for a future range of eruption types with probability paths and hypothetical casualty outcomes for risk assessment. The most likely future eruption scenarios for emergency planning were derived from the event tree and elaborated upon from the geological and historical record. Modelling the impacts in these scenarios and quantifying the consequences for the circumvesuvian area provide realistic assessments for disaster planning and for showing the potential risk–benefit of mitigation measures, the main one being timely evacuation, but include for consideration protecting buildings against dilute, low dynamic pressure surges, and temporary roof supports in the most vulnerable buildings, as well as hardening infrastructure and lifelines. This innovative work suggests that risk-based methods could have an important role in crisis management at cities on volcanoes and small volcanic islands.
    Description: Published
    Description: 454-473
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: open
    Keywords: planning ; emergency ; volcano ; eruption ; mitigation ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 61
    Publication Date: 2017-04-04
    Description: The main CO2 diffuse degassing structures (DDS) of Stromboli were identified through extensive CO2 soil flux investigations, with 3600 measurements by an accumulation chamber. These DDS extend from the nearby crater area of Pizzo sopra la Fossa (Pizzo) to the coastal area of Pizzillo and are all associated with NE–SW deep fractures, corresponding to the main volcano-tectonic axis of the island, some of which produced flank eruptions in prehistoric times. In each of the four main DDS, a target area was defined covering the zone with the highest CO2 soil flux, where periodic CO2 flux surveys were carried out. The highest CO2 release was observed during the 2007 eruption and high flux values were recorded at both Pizzo and Pizzillo also in moments of high prolonged Strombolian activity (high number of daily explosions observed from the craters and/or high frequency of VLP seismic events). In order to better investigate the rate of diffuse CO2 degassing in relation to volcanic activity, an automatic station hourly measuring CO2 soil flux and environmental parameters (atmospheric T, P and humidity, soil moisture and T, wind speed and direction) was installed in March 2007 at Nel Cannestrà and Rina Grande DDS. Unusual positive correlations were found at Nel Cannestrà between gas flux and SE wind speed and at Rina Grande between gas flux and soil moisture, which are explained by the local conditions, which favour respectively a Venturi effect and the increase in gas flux toward the station during rains. Ten months of continuous recording confirmed the strong influence of environmental conditions on the CO2 soil flux, but statistical data processing made it possible to recognize clear positive anomalies expressing high rates of deep magmatic CO2 degassing. Comparison with seismic data indicates that high CO2 fluxes are apparently correlated with increases in volcanic activity, such as higher explosion frequency and VLP amplitude. Particularly promising is the temporal coincidence of highest recorded flux anomaly with a major explosion that occurred during the observation period. Data confirm that the two continuously monitored DDS are preferentially deep degassing sites, where anomalous increases of CO2 release could represent a geochemical precursor for either high energy explosions from the craters or the opening of flank eruptive fissures that might threaten the village of Stromboli.
    Description: In press
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Stromboli ; diffuse CO2 fluxes ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 62
    Publication Date: 2017-04-03
    Description: Volcanic eruptions are characterized by intense degassing, thus it is imperative to have high quality laboratory data to constrain degassing mechanisms. In order to investigate bubble formation and growth at 1 atm, degassing experiments using a Stromboli basalt were performed on the GSECARS X-ray beamline at the Advanced Photon Source. Volatile-bearing glasses were synthesized at 1250 °C and 1000 MPa in a piston cylinder with H2O or mixtures of H2O+CO2; they were then heated in-situ on the X-ray beamline at 1 atm. Bubble growth was observed in-situ using X-ray radiography. The 3D bubble size distributions in the quenched samples and a natural Stromboli pumice were studied by synchrotron X-ray microtomography. The results show that bubble nucleation and growth in basaltic melts are volatile-concentration dependent. Bubbles can easily form in melts initially containing high volatile concentrations. The effect of CO2 on bubble nucleation and growth becomes significant at large CO2 concentrations of 880 to 1480 ppm, but is not important at lower concentrations. Multiple nucleation events occur in most of these degassing experiments, and they are more pronounced in more supersaturated melts. Bubble growth is controlled by viscosity near glass transition temperatures and by diffusion at higher temperatures. Bubbles begin to pop 10 to 20 s after a foam is developed at vesicularities of 65% to 83%. Bubble size distributions follow power–law relations at vesicularities of 1% to 65%, and bubble size distributions evolve from power–law relations to exponential relations at vesicularities of 65% to 83%. This evolution is associated with the change from far-from-equilibrium degassing to near-equilibrium degassing. During far-from-equilibrium degassing, multiple nucleation events are pronounced, and possibly account for the generation of power–law relations. When the system reaches near-equilibrium degassing, coalescence is dominant and leads to the formation of bubbles of similar size. Therefore, bubble size distributions are described by exponential relations.
    Description: NSERC
    Description: Published
    Description: 533-547
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: basalt ; Stromboli ; bubble size distribution ; degassing ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 63
    Publication Date: 2017-04-04
    Description: Historical sources have recorded earthquake shocks, their effects and difficulties that local inhabitants experienced before the AD 79 Pompeii eruption. Archaeological studies pointed out the effects of such seismicity, and have also evidenced that several water crises were occurring at Pompeii in that period. Indeed numerous sources show that, at the time of eruption, and probably some time before, the civic aqueduct, having ceased to be supplied by the regional one, was out of order and that a new one was being built. Since Roman aqueducts were usually built with a recommended minimum mean slope of 20 cm/km and Pompeii's aqueduct sloped from the nearby Apennines toward the town, this slope could have been easily cancelled by uplift that occurred in the area even if this was only moderate. For the crustal deformations a volcanic origin is proposed and a point source model is used to explain the observations. Simple analysis of the available data suggests that the ground deformations were caused by a b2 km3 volumetric change at a depth of ∼8 km that happened over the course of several decades.
    Description: Published
    Description: 959–970
    Description: 5.1. TTC - Banche dati e metodi macrosismici
    Description: JCR Journal
    Description: reserved
    Keywords: Vesuvius ; ground deformation ; seismicity ; stress changes ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.05. Historical seismology ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 64
    Publication Date: 2017-04-04
    Description: In a geothermal area, a detailed knowledge of the three-dimensional velocity structures aids the managementof the field and the further development of the geothermal source. Here,we present a high-resolution study of the three-dimensional S-wave velocity structures from microearthquake travel times for the Larderello-Travale geothermal field, Italy.We have also deduced the Vp/Vs and Vp ×Vs parameters for this area toemphasize the deep variations in the physical rock properties due to fluid content and porosity. Furthermore, effective porousmedium modelling has been performed for site-relevant lithologies, to improve our interpretation of the results in terms of rock physics signatures. This has allowed us to estimate the variation range of the seismological parameters investigated, as well as their sensitivity for suitable rock under specific physical conditions. LowVp/Vs anomalies, arising froma lower Vp compared to Vs, dominate the geothermal field of Larderello-Travale. These have been interpreted as due to steam-bearing formations. On the contrary, analysis of Vp ×Vs images provides information on the relative changes in rock porosity at depth. Comparison of tomographic section images with previously interpreted seismic lines suggests that the reflective ‘K-horizon’ delineates a transition between zones that have different porosities or crack gatherings. The ‘K-horizon’ also lies on low Vp/Vs anomalies, which suggests a steam saturation zone, despite the reduced porosity at this depth.
    Description: In press
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: open
    Keywords: P- and S-wave velocity ; Seismic tomography images ; Geothermal field ; Rock properties ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 65
    Publication Date: 2017-04-04
    Description: We present here some criticism to the scientific content of the paper of Milia et al. [2007. The dark nature of Somma-Vesuvius volcano: evidence from the 3.5 ka B.P. Avellino eruption. Quaternary International, 173–174, 57–66] published in Quaternary International. Milia et al. (2007) interpreted seismic lines in the Gulf of Naples (southern Italy), and inferred the presence of deposits from a large debris avalanche which occurred just before the Avellino eruption of Somma-Vesuvius volcano. The authors supported their seismic profile interpretation with on-land stratigraphies and logs. However, we present here different on-land data that demonstrate the inconsistency of the occurrence of any debris avalanche before or after the Avellino eruption, and we provide also an alternative interpretation for the observed seismic facies offshore of Somma-Vesuvius.
    Description: Published
    Description: 102–109
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: JCR Journal
    Description: open
    Keywords: Somma-Vesuvius volcano ; Avellino eruption ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 66
    Publication Date: 2017-04-04
    Description: The transport, degassing and atmospheric release of halogens from active volcanism on Earth have been the 12 focus of increasing interest over the last few decades, and have recently been the subject of the 1st workshop 13 on “Halogens in volcanic systems and their environmental impacts” that was held in December of 2007 at 14 Yosemite Lodge in Yosemite National Park, California. As an introduction to this Chemical Geology special 15 issue, collecting contributions from many of the participants at the workshop, we review here recent 16 advances in this field, including experimental and theoretical investigations of halogen behaviour in volcanic 17 and related magmatic systems. We discuss previous research on several aspects of halogen geochemistry, 18 including halogen abundances in the mantle and magmas on Earth; the effects of halogens on phase 19 equilibria and melt viscosities; their partitioning between melt and fluid phase(s) upon decompression, 20 cooling and crystallisation of magmas in the ^ Earth's crust; and their final atmospheric release as volcanic 21 gases. The role of halogens in the genesis of hydrothermal systems and in the transport of ore-forming metals 22 is also reviewed, and we discuss our current understanding of atmospheric processing of volcanic halogens in 23 both the troposphere and stratosphere, and their consequent impacts. In spite of these recent advancements, 24 our current understanding of halogen geochemistry at active volcanoes is still far too fragmentary, and the 25 key questions that require answers from future research are summarised in our conclusions.
    Description: PRIN 2008 and DPC-INGV 1381 2007-2009 grants; NSERC Dis- 1382 covery grant; NSF award EAR 0308866
    Description: In press
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: Halogens ; Volcanic gas ; Ore deposits ; Atmospheric effects ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 67
    Publication Date: 2017-04-04
    Description: Inversion of large-scale potential-field anomalies, aimed at determining density or magnetization, is usually made in the Fourier domain. The commonly adopted geometry is based on a layer of constant thickness, characterized by a bottom surface at a fixed distance from the top surface. We propose a new method to overcome this limiting geometry, by inverting in the usual iterating scheme using top and bottom surfaces of differing, but known shapes. Randomly generated synthetic models will be analyzed, and finally performance of this method will be tested on real gravity data describing the isostatic residual anomaly of the Southern Tyrrhenian Sea in Italy. The final result is a density model that shows the distribution of the oceanic crust in this region, which is delimited by known structural elements and appears strongly correlated with the oceanized abyssal basins of Vavilov and Marsili.
    Description: Published
    Description: 105-111
    Description: 2.6. TTC - Laboratorio di gravimetria, magnetismo ed elettromagnetismo in aree attive
    Description: JCR Journal
    Description: reserved
    Keywords: Potential field ; Inversion ; Mathematical modeling ; Tyrrhenian Sea ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.02. Exploration geophysics::04.02.02. Gravity methods
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 68
    Publication Date: 2017-04-04
    Description: We have developed two new quantitative approaches to calculate temperatures in hydrothermal reservoirs by using the CO2-CH4-CO-H2 gaseous system and to model selective dissolution of CO2-H2S-N2-CH4-He-Ne mixtures in fresh and/or air saturated seawater. The anomalous outgassing starting November 2003 from the submarine exhalative system offshore Panarea island (Italy), was the occasion to apply such approaches to the extensive collection of volcanic gases. Gas geothermometry suggest the presence of a deep geothermal system at temperature up to 350°C and about 12 mol% CO2 in the vapor, which feeds the submarine emissions. Based on the fractional dissolution model, the rising geothermal vapor interacts with air-saturated seawater at low depths, dissolving 30-40% CO2 and even more H2S, modifying the pH of the aqueous solution and stripping the dissolved atmospheric volatiles (N2, Ne). Interaction of the liquid phase of the thermal fluids with country rocks, as well extensive mixing with seawater, have been also recognized and quantified. The measured output of hydrothermal fluids from Panarea exhalative field [1] accounts for the involvement of volatiles from an active degassing magma, nonetheless the climax of the investigated phenomenon is probably overcome and the system is new tending towards a steady-state. Our quantitative approaches allow us to monitor the geochemical indicators of the geothermal physico-chemical conditions and their potential evolution towards phreatic events or massive gas releases, which certainly are the main hazards to be expected in the area. The event at Panarea has in fact highlighted how hydrothermal systems can exhibit dramatic and sudden changes of their physico-chemical conditions and rate of fluid release, as a response to variable activity of feeding magmatic systems.
    Description: Published
    Description: Copenhagen
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: open
    Keywords: Submarine ; geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Extended abstract
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  • 69
    Publication Date: 2017-04-03
    Description: Microearthquake recordings of local events have been used to quantify the site effects in the vicinity of Bursa City, northwest Turkey. Since the city is located near the southwest branch of the western extension of the North Anatolian Fault (NAF) zone, the importance of the seismic hazard in the region becomes progressively more important. The accelerograms of 69 earthquakes that were recorded on different geologic units, massive limestone, slope deposit and Quaternary sediment were analyzed to estimate the response of the recording sites. Site amplification functions were obtained by using three different approaches (standard spectral ratio, SSR; horizontal to vertical, H/V ratio and generalized inversion method, GIM) and the differences between the methods were also evaluated. We found large discrepancies between the SSR and H/V ratio methods, specifically; the former yields almost three times higher amplitudes than those obtained in the latter approach. Station located within the Bursa Quaternary basin (SCKR) is characterized by the largest estimates of the amplification amplitudes (8.0, 4.5 and 4.0 for SSR, H/V ratio and GIM, respectively) in all the three methods. On the other hand, stations located on deep limestone geological unit (SIGD and SKAY) show the least amplification level, ranging between 1.0 and 1.6. Three methods are able to identify resonant frequencies of the sites, although the absolute amplitudes of the amplification function are obtained different from each method.
    Description: Published
    Description: 579-587
    Description: JCR Journal
    Description: reserved
    Keywords: site amplification, Bursa city, Turkey, ground motion ; Northwestern Anatolian Fault, seismic hazard ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
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  • 70
    Publication Date: 2017-04-04
    Description: Magnetic observations over the area of the Transantarctic Mountains (TAM) and the Ross Sea have been compiled into a digital database that furnishes a new regional scale view of the magnetic anomaly crustal field in this key sector of the Antarctic continent. This compilation is a component of the ongoing IAGA/SCAR Antarctic Digital Magnetic Anomaly Project (ADMAP). The aeromagnetic surveys total 115000 line km, and are distributed across the Victoria Land sector of the TAM, the Ross Sea, and Marie Byrd Land. The magnetic campaigns were performed within the framework of the national and international Italian–German–US Antarctic research programs and conducted with differing specifications during nine field seasons from 1971 until 1997. Generally flight line spacing was less than 5 km while survey altitude varied from about 610 to 4000 m above sea level for barometric surveys and was equal to 305 m above topography for the single draped survey. Reprocessing included digitizing the old contour data, improved levelling by means of microlevelling in the frequency domain, and re-reduction to a common reference field based on the DGRF90 model. A multi-frequency grid procedure was then applied to obtain a coherent and merged total intensity magnetic anomaly map. The shaded relief map covers an area of approximately 380000 km2. This new compilation provides a regional image of the location and spatial extent of the Cenozoic alkaline magmatism related to the TAM–Ross Sea rift, Jurassic tholeiites, and crustal segments of the Early Palaeozoic magmatic arc. A linear, approximately 100-km wide and 600-km long Jurassic rift-like structure is newly identified. Magnetic fabric in the Ross Sea rift often matches seismically imaged Cenozoic fault arrays. Major buried onshore pre-rift fault zones, likely inherited from the Ross Orogen, are also delineated. These faults may have been reactivated as strike-slip belts that segmented the TAM into various crustal blocks.
    Description: Published
    Description: 121-137
    Description: JCR Journal
    Description: reserved
    Keywords: Antarctica ; Magnetic anomalies ; Tectonic structures ; Magmatism ; Geomagnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.04. Magnetic anomalies ; 04. Solid Earth::04.05. Geomagnetism::04.05.05. Main geomagnetic field ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 05. General::05.01. Computational geophysics::05.01.01. Data processing
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  • 71
    Publication Date: 2017-04-04
    Description: Observations from a network of specially equipped GPS scintillation receivers in Northern Europe are used to investigate the dynamics of ionospheric plasma during the storm events of 30 October and 20 November 2003. The total electron content (TEC) and scintillation data, combined with ionospheric tomography produced by the multi-instrument data analysis system (MIDAS), reveal strong enhancements and steep gradients in TEC during nighttime under a prevailing negative Bz component of the interplanetary magnetic field (IMF). Amplitude and phase scintillation maxima are often co-located with the TEC gradients at the edge of plasma patches, revealing the presence of small-scale irregularities and suggesting association with a tongue of ionization (TOI) convecting in an anti-sunward direction from the American sector across the polar cap. Similarities and differences between the ionospheric response to the two storms are investigated. The 30 October event reveals a quite complex scenario showing two phases of plasma dynamics: the former reflects the expected convection pattern for IMF Bz southward and the latter possibly indicates a sort of TEC plasma stagnation signature of the more complex convection patterns during several positive/negative excursions of IMF Bz.
    Description: Published
    Description: 879-888
    Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
    Description: JCR Journal
    Description: reserved
    Keywords: Ionospheric scintillations ; Polar pathches ; GPS ; Plasma dynamics ; 01. Atmosphere::01.02. Ionosphere::01.02.02. Dynamics ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques ; 05. General::05.07. Space and Planetary sciences::05.07.01. Solar-terrestrial interaction ; 05. General::05.07. Space and Planetary sciences::05.07.02. Space weather
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  • 72
    Publication Date: 2017-04-04
    Description: Recent developments in paleomagnetism and environmental magnetism provide new tools for the detailed correlation of climatically induced magnetic mineralogy changes in sedimentary sequences. Studies of these changes contribute to the reconstruction of climate history for the glacial^interglacial cycles of the Late Pleistocene and to the delineation of the range of natural variability for global climate during the past hundred thousands years. Here we show that sharp coercivity minima observed in fine-grained sediments from the continental rise of the western Antarctic Peninsula correlate to the major rapid cooling events of the northern Atlantic (Heinrich layers). We interpret such an environmental magnetic signal in terms of variations in deep sea diagenetic processes of sulfide formation, which reflect changes in the input of detrital organic matter controlled by sea-ice extent. With the inherent uncertainties in age controls, the sedimentary paleoclimatic markers of the two hemispheres are almost contemporaneous, but interhemispheric time lags or leads of the order of 1-2 kyr (such as those recently reported from the Greenland and Antarctic ice cores) are also compatible with the data.
    Description: Published
    Description: 65-80
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: paleomagnetism ; paleointensity ; Antarctica ; Heinrich events ; climatic correlation ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 73
    Publication Date: 2017-04-04
    Description: 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.
    Description: Published
    Description: 53-64
    Description: JCR Journal
    Description: reserved
    Keywords: 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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  • 74
    Publication Date: 2017-04-04
    Description: We report on the anisotropy of magnetic susceptibility (AMS) analyses of fine-grained sediments deposited during the Messinian in foredeep basins at the front of the northern Apenninic chain. The data refer to 32 sampling sites, mostly distributed in the fine-grained intervals of the Laga and Colombacci formations, extending along the belt for a total length of about 300 km. Rock magnetism analyses indicate that the magnetic susceptibility and its anisotropy are in most cases dominated by the paramagnetic minerals of the clay matrix. In order to delineate the contribution of the ferrimagnetic fraction to the overall susceptibility fabric, the anisotropy of the anhysteretic remanent magnetisation was investigated at some representative sites. The magnetic fabric of the studied sediments mostly reflects the effects of compaction, showing a predominant magnetic foliation parallel to the bedding piane. At all the sites a well distinct magnetic lineation was also found, which is parallel to the fold axes and thrust fronts, both at local and regional scales. This feature is maintained in sequences that differ for sedimentological character and age, implying that the magnetic lineation was produced by a mild tectonic overprint of the primary sedimentary-compactional fabric. The relationship between the magnetic lineation trends and the vertical axis rotations detected by Speranza et al. [Speranza, F., Sagnotti, L.. Mattei, M., 1997. J. Geophys. Res. 102, 3153-3166] indicates that the magnetic lineation formed during the compressive phases of the Messinian-early Pliocene, when the Apenninic front was almost rectilinear and oriented N32O°.
    Description: Published
    Description: 73-93
    Description: JCR Journal
    Description: reserved
    Keywords: magnetic anisotropy ; rock strain ; northern Apennines ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 75
    Publication Date: 2017-04-04
    Description: This special issue on "Antarctic Climate Evolution — view from the margin" presents results from modelling studies and reports on geoscience data aimed at improving our understanding of the behaviour of the Antarctic ice sheet and the climate of the region. This research field is of interest because of the sensitivity of the polar regions to global warming, and because of the influence of the Antarctic ice sheet on global sea level and climate through most if not all of the Cenozoic Era. The Antarctic ice sheet both responds to and forces changes on global climate and sea level. We need to be aware of the scale and frequency of these changes if we are to understand past patterns of environmental change elsewhere on earth. It was only three decades ago that we discovered from strata drilled in shelf basins on the Antarctic margin that the Antarctic ice sheet had a history that predated the Quaternary ice ages by over 20 million years (Hayes et al., 1975). Later that year the first interpretation of Antarctic glacial history through the Cenozoic Era from oxygen isotopes, recorded in foraminifera from deep-sea sediment cores, was published (Shackleton and Kennett, 1975). Revisions with a more extensive database have modified the story a little (Miller et al., 1987; Zachos et al., 2001), and there have been recent attempts to resolve the temperature–ice volume ambiguity (Lear et al., 2000). However, reports on strata drilled on the Antarctic margin have unambiguously shown the character of this huge ice sheet, which was oscillating in the Oligocene (Barrett et al., 1987; Barrett, 1999) with a period and magnitude comparable with the Northern Hemisphere ice sheets of the Quaternary (Naish et al., 2001a,b). In this issue we present further research on the history of the Antarctic ice sheet from Oligocene to recent times, most of them from the Antarctic margin, but with some on the nature of the deep-sea isotope record, and others using recently developed modeling techniques to investigate the influence of atmosphere, ocean and biosphere on past Antarctic climate. This special issue is the third in three years on the theme of Antarctic Climate Evolution. The first followed a workshop in Erice, Sicily, in 2001 to report on results from ANTOSTRAT, a SCAR-sponsored project for gathering and analysing circum-Antarctic seismic data for planning and promoting offshore drilling for climate history. The introduction to that issue (Florindo et al., 2003) provides a review of the recent history of circum-Antarctic drilling by the Ocean Drilling Program (Legs 113, 114, 119, 120, 177, 178, 188 and 189) and the Cape Roberts Project. For a more comprehensive review of earlier drilling in the Ross Sea region (Deep Sea Drilling Project Leg 28, Dry Valley Drilling Project, McMurdo Sound Sediment and Tectonic Studies, Cenozoic Investigations in the western Ross Sea) see Hambrey and Barrett (1993). The first of these issues (Florindo et al., 2003) featured a global plate reconstruction of the Southern Hemisphere through Cenozoic time with emphasis on evolution of Cenozoic seaways (Lawver and Gahagan, 2003) along with a study of the inception and early evolution of the EAIS using a new coupled global climate (GCM)– dynamic ice sheet model (DeConto and Pollard, 2003b), as well as data from recent drilling around the margin covering time period from Cretaceous to the present. A second special issue on the same theme (Florindo et al., 2005) also featured a mix of modelling and data papers with a focus on the Eocene–Oligocene boundary and the initiation of ice sheet growth, including a pioneering attempt to evaluate the relative influence of fluvial versus glacial processes in shaping the landscape of the Prydz Bay sector of Antarctica (Jamieson et al., 2005). The remainder of the issue comprised further papers on seismic stratigraphy and reports from drilling around the margin. The papers to be found in this special issue, like the previous two, maintain the mix of modelling- and data-oriented papers that reflect the range of this research.
    Description: Published
    Description: 1-8
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: reserved
    Keywords: Antarctic climate evolution ; 03. Hydrosphere::03.01. General::03.01.06. Paleoceanography and paleoclimatology
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  • 76
    Publication Date: 2017-04-04
    Description: We present here a new hypothesis to explain the high mobility of same rapid mass movements of rock fragments. We suggest that oscillations of flows with a quasi-rigid plug can result in reduction of their apparent coefficient of friction. This coefficient is computed as the ratio between drop in elevation and horizontal distance of travel. In our model, the effective friction during a downhill journey is a combination of the friction forces acting on the plug during the ascending and descending parts of its slope-normal oscillations. As a consequence of oscillations, the decreased contact with ground surface reduces the apparent coefficient of friction. Channel lateral surfaces can also support a portion of plug weight giving another contribution in the reduction of this coefficient. The support of lateral surfaces requires a relatively narrow channel such as a gully or the presence of levees whereas the reduced basal contact can be important also in larger channels that do not provide lateral support. We suggest that slope-normal oscillations are generated by ground asperities. The true coefficients of friction are larger than the apparent one because they account energetically for the oscillations that reduce basal contact. Thus we can say that our model is able to explain long runout distances as long as the energy dissipated by oscillations is accounted for by the true coefficients of friction that enter the calculations. Field and experimental investigation of the several ideas discussed in this paper constitutes important aspects of future research that will improve the understanding of granular flows mobility.
    Description: In press
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Pyroclastic flows ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 77
    Publication Date: 2017-04-04
    Description: By analyzing an oblique ionogram several characteristics, such as LOF, MOF, FMUF, FHLOF, FLLOF, and 2FMOF, can be found. These characteristics are important both for ionospheric studies and for terrestrial communication purposes, as they give information about the sky wave communication conditions in the High Frequency (HF) radio spectrum. A RCS-5B sweeping HF receiver for oblique sounding was installed at Chania (Crete, Greece, 35.71N, 24.01E) in April 2005 to perform a radio link with Inskip (UK, 53.51N, 2.51W). The receiver, able to record the sounding only as a binary file, was not equipped with a tool to display and scale the recorded trace. This work describes software that is able to do this, consequently increasing the speed of the scaling phase performed by the operator. The usefulness of this software for validating FMUF prediction models is also shown.
    Description: Published
    Description: 1577–1583
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
    Description: JCR Journal
    Description: reserved
    Keywords: Ionospheric monitoring ; Ionogram scaling ; Maximum usable frequency ; 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous ; 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
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  • 78
    Publication Date: 2017-04-04
    Description: 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.
    Description: Published
    Description: 64-70
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: 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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  • 79
    Publication Date: 2017-04-04
    Description: A 350m deep boreholewas drilled in the Colli Albani volcanic district (Central Italy) in order to: understand the shallow crust structure beneath the volcanic complex; characterize the rock physical properties especially through in-situ measurements and, afterward, laboratory experiments; assess the local present-day stress field; install a broad-band seismometer at depth. The borehole is located adjacent to the western rim of the Tuscolano–Artemisio caldera, where several phenomena of unrest recently occurred. In 1989–90 a seismic swarm affected this area and a related uplift was recognized. In addition, high gas concentrations (mainly CO2 and H2S), in aquifers and soils, caused illnesses and casualties among inhabitants and animals in the past. We describe the investigations carried out at the drill site and the results achieved from data analysis.Wire-line drilling produced a complete stratigraphic record of the Quaternary volcanic units down to the Plio–Pleistocene sedimentary sequence and geophysical logs allowed a characterization of the rock physical properties. From a tectonic point of view, data provided by Dipmeter and Borehole Televiewer were used for investigations on the recent and present-day stress field and the results are compared to those available in the literature. In the volcanic units we recognized two main fracture systems, SW and NW dipping. Several faults intersecting the borehole showplaneswith oblique striae, indicating a prevalent strike–slip component of the movement. Finally, borehole breakout analysis defined an active stress field with a ∼E–Woriented minimum horizontal component. At the end of the drilling, a blow-out occurred, due to pressurized fluids trapped into the sandy unit drilled in the last fewmeters of the hole. Sampling these fluids gave an additional value to the borehole, providing information about the deep volcanic circulation and its possible connection to a deep-seated magma chamber. The main results show water with a Na–HCO3 chemistry and the highest salinity ever recognised in the area (Electrical Conductivity=10.12 mS/cm). Stable O and H isotopes reveal ameteoric origin ofwater and the absence of tritium points out a long residence time in the aquifer. Emitted gas is CO2-dominated, with N2 as second most important component. Helium isotopic composition of the gas allows us to estimate a magmatic component ranging in the interval 40–50%, one of the highest in the Colli Albani. Carbon isotopes of CO2 (−0.53‰ vs. PDB) suggest that it could derive partly froma magmatic source and partly by the thermal decarbonation of the carbonatic basement.
    Description: Published
    Description: 225-240
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: scientific drilling ; volcanic stratigraphy ; wireline logs ; fluid geochemistry ; Italy ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
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  • 80
    Publication Date: 2017-04-04
    Description: A transect of three sites was drilled during Leg 188 of the Ocean Drilling Program (ODP), proximal to the East Antarctic Ice Sheet (EAIS) across the Prydz Bay continental shelf (Site 1166), slope (Site 1167), and rise (Site 1165). We present results of a palaeomagnetic and rock magnetic study of sediments recovered at sites 1165 and 1166. Magnetostratigraphic interpretations are presented for both holes and are mainly constrained by diatom and radiolarian biostratigraphies, interpreted in the light of recent refinements to Southern Ocean zonal schemes and datum calibrations for these microfossil groups. Site 1165 records a history of sedimentation on the continental rise extending back to earliest Miocene times (about 22 Ma). Several long-term changes characterise this record, including an overall trend of decreasing sedimentation rates from the bottom to the top of the hole. There is a progressive decrease in the sedimentation rate above about 308 mbsf (meters below sea floor), which is marked by a transition from dark-grey fissile claystones to greenish-grey diatom-bearing clays. At this transition, ice-rafted debris, sand grains, and total clay content also increase. The chronology presented here indicates a middle Miocene age (~14.3 Ma) for the lithological transition. Correlation to ODP Hole 747A from the Kerguelen Plateau suggests that this lithological transition coincides with the base of the Mi-3/3a δ18O event, which suggests palaeoclimatic control on middle Miocene sedimentation changes at Site 1165. Core recovery was poor at Site 1166. Consequently, the magnetostratigraphic data are of limited value. The deepest cores recovered at Site 1166 record brief intervals in the early history of the EAIS for the Prydz Bay region, extending back through the early stage of glaciation to pre-glacial times. An Early Cretaceous fluvio-lacustrine unit, lagoonal deposits and sandy fluvio-deltaic units of mid-late Eocene age contain a sporadic record of the transition from humid and mild conditions to cool temperate conditions.
    Description: Published
    Description: 69-100
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: magnetostratigraphy ; biostratigraphy ; Prydz Bay ; Antarctica ; Ocean Drilling Program ; sites 1165 and 1166 ; 03. Hydrosphere::03.01. General::03.01.06. Paleoceanography and paleoclimatology ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
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  • 81
    Publication Date: 2017-04-04
    Description: 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.
    Description: 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.
    Description: Published
    Description: 110-121
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: 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
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  • 82
    Publication Date: 2017-04-04
    Description: Italy has one of the most complete and historically extensive seismic catalogues in the World due to a unique and uninterrupted flow of written sources that have narrated its seismic history since about the end of the Iron Age. Seismic hazard studies have therefore always been mainly based upon this huge mass of data. Nevertheless, the Italian catalogue probably “lacks” many M≥6.5 events, the seismogenetic structures responsible for which are characterized by recurrence times that are longer than the time span covered by our historical sources. For these reasons, and as in other countries, earthquake data that in Italy have been derived from paleoseismological studies should finally become a necessary ingredient in seismic risk assessment. Indeed, over the past 20 years, some hundred trenches have been excavated, supplying reliable and conclusive data on the recent activities of many faults. Through to many robust datings of surface fault events, these studies have provided the ages of several unknown or poorly known M≥6.5 earthquakes. Here, we summarize the state of the art of paleoseismology in Italy, and present a first catalogue of 56 paleoearthquakes (PCI) that occurred mainly in the past 6 kyr. The PCI integrates the historical/instrumental seismic catalogue, and extends it beyond the recurrence time of the seismogenetic faults (2000±1000 yr). We feel confident that the use of the PCI will enhance future probabilistic seismic hazard assessment, and thus contribute to more reliable seismic risk mitigation programs.
    Description: Published
    Description: 89-117
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: Italy ; paleoearthquakes ; catalogue of paleoseismicity ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology
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  • 83
    Publication Date: 2017-04-04
    Description: 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.
    Description: In press
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: 4.2. TTC - Scenari e mappe di pericolosità sismica
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: 4.4. Scenari e mitigazione del rischio ambientale
    Description: JCR Journal
    Description: reserved
    Keywords: 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
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  • 84
    Publication Date: 2017-04-04
    Description: 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.
    Description: In press
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: 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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  • 85
    Publication Date: 2017-04-04
    Description: 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.
    Description: In press
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 4.4. Scenari e mitigazione del rischio ambientale
    Description: 4.5. Degassamento naturale
    Description: JCR Journal
    Description: reserved
    Keywords: 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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  • 86
    Publication Date: 2017-04-04
    Description: 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.
    Description: Published
    Description: 115-128
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: reserved
    Keywords: 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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  • 87
    Publication Date: 2017-04-04
    Description: This paper focuses on the role that hydrothermal systems may play in caldera unrest. Changes in the fluid chemistry, temperature, and discharge rate of hydrothermal systems are commonly detected at the surface during volcanic unrest, as hydrothermal fluids adjust to changing subsurface conditions. Geochemical monitoring is carried out to observe the evolving system conditions. Circulating fluids can also generate signals that affect geophysical parameters monitored at the surface. Effective hazard evaluation requires a proper understanding of unrest phenomena and correct interpretation of their causes. Physical modeling of fluid circulation allows quantification of the evolution of a hydrothermal system, and hence evaluation of the potential role of hydrothermal fluids during caldera unrest. Modeling results can be compared with monitoring data, and then contribute to the interpretation of the recent caldera evolution. This paper: 1) describes the main features of hydrothermal systems; 2) briefly reviews numerical modeling of heat and fluid flow through porous media; 3) highlight the effects of hydrothermal fluids on unrest processes; and 4) describes some model applications to the Phlegrean Fields caldera. Simultaneous modeling of different independent parameters has proved to be a powerful tool for understanding caldera unrest. The results highlight the importance of comprehensive conceptual models that incorporate all the available geochemical and geophysical information, and they also stress the need for high-quality, multi-parameter monitoring and modeling of volcanic activity.
    Description: Published
    Description: 393-416
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: reserved
    Keywords: hydrothermal fluids ; unrest ; modeling ; caldera ; monitoring ; volcanic hazard ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 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)
    Type: book chapter
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  • 88
    Publication Date: 2017-04-04
    Description: We have here analysed two normal faults of the central Apennines, one that affects the south-western slopes of theMontagna dei Fiori–Montagna di Campli relief, and the other that is located along the south-western border of the Leonessa intermontane depression. Through this analysis, we aim to better understand the reliability of geomorphic features, such as the fresh exposure of fault planes along bedrock scarps as certain evidence of active faulting in the Apennines, and to define the Quaternary kinematic history of these tectonic structures. The experience gathered from these two case studies suggests that the so-called ‘geomorphic signature’ of recent fault activity must be supported by wider geomorphologic and geologic investigations, such as the identification of displaced deposits and landforms not older than the Late Pleistocene, and/or an accurate definition of the slope instabilities. Our observations indicate that the fault planes studied are exposed exclusively because of the occurrence of non-tectonic processes, i.e. differential erosion and gravitational phenomena that have affected the portions of the slopes that are located in the hanging wall sectors. The geological evidence we have collected indicates that the Montagna dei Fiori–Montagna di Campli fault was probably not active during the whole of the Quaternary, while the tectonic activity of the Leonessa fault ceased (or strongly reduced) at least during the Late Pleistocene, and probably since the Middle Pleistocene. The present lack of activity of these tectonic structures suggests that the fault activation for high magnitude earthquakes that produce surface faulting is improbable (i.e. M〉5.5–6.0, with reference to the Apennines, according to Michetti et al. [Michetti, A.M., Brunamonte, F., Serva, L.,Vittori, E. (1996), Trench investigations of the 1915 Fucino earthquake fault scarps (Abruzzo, Central Italy): geological evidence of large historical events, J. Geoph. Res.,101, 5921–5936; Michetti, A.M., Ferreli, L., Esposito, E., Porfido, S., Blumetti, A.M., Vittori, E., Serva, L., Roberts, G.P. (2000)]). If, according to the current view, the shifting of the intra-Apennine extension towards the Adriatic sectors is still active, the Montagna dei Fiori–Montagna di Campli fault might be involved in active extensional deformation in the future.
    Description: Partnership between the Istituto Nazionale di Geofisica e Vulcanologia and the Provincia di Teramo (2004–2005)
    Description: In press
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: Bedrock fault scarps ; Exhumation ; Non-tectonic processes ; Seismic hazard ; Extensional domain migration ; Central Italy ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 89
    Publication Date: 2017-04-04
    Description: Four groups of thermal springs with temperatures from 50 to 80 °C are located on the S–SW–W slopes of El Chichón volcano, a composite dome-tephra edifice, which exploded in 1982 with a 1 km wide, 160 m deep crater left. Very dynamic thermal activity inside the crater (variations in chemistry and migration of pools and fumaroles, drastic changes in the crater lake volume and chemistry) contrasts with the stable behavior of the flank hot springs during the time of observations (1974–2005). All known groups of hot springs are located on the contact of the basement and volcanic edifice, and only on the W–SW–S slopes of the volcano at almost same elevations 600–650 m asl and less than 3 km of direct distance from the crater. Three groups of near-neutral (pH≈6) springs at SW–S slopes have the total thermal water outflow rate higher than 300 l/s and are similar in composition. The fourth and farthest group on the western slope discharges acidic (pH≈2) saline (10 g/kg of Cl) water with a much lower outflow rate (b10 l/s). Water–rock interaction modeling of main types of the El Chichón thermal waters using regular log Q/K graphs (saturation indices vs temperature) showed maximum equilibrium temperature slightly higher than 200 °C. Acidic waters are equilibrated with some clay minerals at about 120 °C. Three main sources of the salinity of thermal water are suggested on the basis of mixing plots and isotopic data: a magmatic source for CO2, boron, sulfur and a limited part of Cl; volcanic rock source for the major cations and trace elements; the oil-bearing evaporitic basement source (oil-field brine?) for NaCl, Br, a part of Ca and some trace elements. All flank thermal springs end up in the river Rio Magdalena that has a variable seasonal flow rates from 4 to 20 m3/s. Any changes in the chemistry of springs must notably change the composition of the streams draining hot springs and eventually, Rio Magdalena. A monthly geochemical monitoring of Rio Magdalena and streams draining main hot springs would be a useful tool for surveying the activity of the volcano.
    Description: Published
    Description: 224–236
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: JCR Journal
    Description: reserved
    Keywords: volcano–hydrothermal system ; crater lake ; acidic water ; trace elements ; thermochemical modeling ; El Chichón volcano ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 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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  • 90
    Publication Date: 2017-04-04
    Description: 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
    Description: Published
    Description: 286–298
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: 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)
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  • 91
    Publication Date: 2017-04-04
    Description: No Abstract
    Description: Published
    Description: V-IX
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Rischio Vulcanico ; Exploris ; Vulcani esplosivi ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 92
    Publication Date: 2017-04-04
    Description: The determination of the earthquake energy budget remains a challenging issue for Earth scientists, as understanding the partitioning of energy is a key towards the understanding the physics of earthquakes. Here we estimate the partition of the mechanical work density into heat and surface energy (energy required to create new fracture surface) during seismic slip on a location along a fault. Earthquake energy partitioning is determined from field and microstructural analyses of a fault segment decorated by pseudotachylyte (solidified friction-induced melt produced during seismic slip) exhumed from a depth of ~10 km—typical for earthquake hypocenters in the continental crust. Frictional heat per unit fault area estimated from the thickness of pseudotachylytes is ~27 MJ m−2. Surface energy, estimated from microcrack density inside clast (i.e., cracked grains) entrapped in the pseudotachylyte and in the fault wall rock, ranges between 0.10 and 0.85 MJ m−2. Our estimates for the studied fault segment suggest that ~97–99% of the energy was dissipated as heat during seismic slip. We conclude that at 10 km depth, less than 3% of the total mechanical work density is adsorbed as surface energy on the fault plane during earthquake rupture.
    Description: Published
    Description: 131 - 139
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: Fracture energy ; 04. Solid Earth::04.01. Earth Interior::04.01.04. Mineral physics and properties of rocks
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 93
    Publication Date: 2017-04-04
    Description: Between November 2nd and 3rd 2002 a shallow submarine gas eruption occurred in the area between Lisca Bianca, Bottaro and Lisca Nera islets located about 2.5 km from Panarea Island, in the Aeolian volcanic archipelago, Southern Italy. To estimate the current crustal deformation of this active volcanic area and to evaluate its volcanic hazard, a local GPS network was set up and repeatedly surveyed in the time span December 2002 - October 2005, with the aim to monitor the evolution of the crustal deformation related with the exhalative crisis. The local GPS network consists in 11 GPS stations located in the Panarea archipelago. First results show vertical movements and an active strain, up to 20x 10-6 across the islets. Strain axes display NNW-SSE extension and ENE-WSW compression. We interpret these data as relative to the deflation of the area, after the exhalative crisis, along existing tectonic structures. Present day observation of the exhalative field confirm that the gas emission migrated from NE to NW oriented fractures, in agreement with the strain tensor changes with time, estimated through GPS data.
    Description: This work has been funded by Italian Dipartimento della Protezione Civile.
    Description: In press
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: JCR Journal
    Description: open
    Keywords: GPS,Aeolian arc, Panarea, gas eruption ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.07. Tectonophysics::04.07.08. Volcanic arcs
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 94
    Publication Date: 2017-04-04
    Description: 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.
    Description: Published
    Description: 223–235
    Description: 1.10. TTC - Telerilevamento
    Description: 3.6. Fisica del vulcanismo
    Description: 5.4. TTC - Sistema Informativo Territoriale
    Description: JCR Journal
    Description: reserved
    Keywords: 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
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  • 95
    Publication Date: 2017-04-04
    Description: Diffusion of halogens has the potential to influence petrogenetic processes in magma chambers and conduit degassing processes. This contribution reviews our current state of knowledge concerning halogen diffusion and the influence of halogens on the diffusion of major elements in silicate melts. The addition of halogens to silicate melts at common, natural concentration levels will have little effect on the diffusion of major elements. However, the differences between the diffusivity of water, the diffusivities of halogens, and the diffusivity of sulfur are significant enough that during melt inclusion entrapment, or during rapid bubble or crystal growth, diffusive fractionation betweenwater and the halogens, and between halogens and sulfur, are expected to occur and can influence the compositions of melt inclusions, crystals and volcanic gases.
    Description: NSERC Discovery grant to D.R.B
    Description: In press
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: Halogens ; Diffusion ; Magmatic processes ; Volcanic gas ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 96
    Publication Date: 2017-04-04
    Description: The 1631 Vesuvius eruption is one of its best known and most studied of its type. However, the historical approach performed within the framework of the Exploris project highlighted new evidence from previously unused or unknown historical sources. These consist of three treatises that were contemporary to the event; although written in Latin, they have been fully translated and analysed. To guarantee systematic use and open access to the large amount of information they contain, they have been provided as a small database. These treatises have provided new information on phenomena that preceded and accompanied the eruption of 1631, making possible the formation of a complex chronological profile, starting from around 6 months before the eruption. The anthropic impact is also outlined. The method applied has produced a chronology of “cold data”, which are not interpreted from the volcanological standpoint, but only derived directly from the analysed history and sequence of the texts. The analysis of the three treatises has not, however, solved all of the problems connected with the detailed knowledge of the event in 1631. Indeed, problems of two kinds persist: a) linguistic correspondence between the volcanological terms of today and those used in the texts; b) the lack of precision of the measures indicated. Here, the main results obtained from this analysis method are presented, along with a discussion of their limitations and some new perspectives.
    Description: Published
    Description: 347-358
    Description: 3.10. Sismologia storica e archeosismologia
    Description: JCR Journal
    Description: reserved
    Keywords: historical volcanology ; Vesuvius ; 1631 eruption chronology ; precursors ; treatises ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 97
    Publication Date: 2017-04-04
    Description: 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.
    Description: Published
    Description: 277-287
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: JCR Journal
    Description: reserved
    Keywords: 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
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  • 98
    Publication Date: 2017-04-04
    Description: 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.
    Description: Published
    Description: 133-144
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 99
    Publication Date: 2017-04-04
    Description: 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.
    Description: Published
    Description: 325-336
    Description: JCR Journal
    Description: reserved
    Keywords: 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 100
    Publication Date: 2017-04-04
    Description: We develop a steady-state, two-phase flow model of magma ascent through an axisymmetric conduit of variable radius R and length L in order to quantify relationships between conduit geometry and magma ascent dynamics. Holding boundary conditions and chamber magma properties constant, we vary conduit geometry systematically and independently, such that the upper conduit radius increases or decreases by a factor of Rt /Rb (radius ratio; 0.4 ≤ Rt /Rb ≤ 2.5), above a change initiation height H (0.1 ≤ H /L ≤ 0.7), and over length Le (Le /L = 0.2), where Rt and Rb are conduit radius above (t) and below (b) the radius change and H is the height above the top of the magma chamber. Conduit widening causes a drop in overpressure and corresponding increase in gas volume fraction and magma acceleration over the whole length of the conduit, with all changes increasing in magnitude with increasing radius ratio. Magma ascent rate increases roughly as R2 and volumetric flow rate subsequently increases as R4 when Rt = Rb = R. Both increasing Rt for a fixed Rb (increasing radius ratio) and increasing Rb for a fixed Rt (decreasing radius ratio), increase volume flow and magma ascent rates. Compared to changes in geometry, small changes in chamber pressure (〈 5%) have a weak effect on flow rate. Many model runs produce a magma plug at the top of the conduit, largely due to permeable gas loss through conduit walls. In general, large radii and low radius ratios (i.e., nearly cylindrical conduits) favor thin, low-density plugs, which may facilitate sudden destruction of a plug, and thus enhance the likelihood of explosive over extrusive eruptions. These findings suggest that changes in conduit geometry, such as those caused by conduit erosion during explosive eruptions or by accretion of magma along conduit walls, are strongly coupled to magma ascent dynamics and should not be ignored when interpreting changes in eruptive behavior.
    Description: Published
    Description: 567-578
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: conduit dynamics ; conduit geometry ; magma ascent ; effusion rate ; computational model ; 05. General::05.01. Computational geophysics::05.01.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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