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  • 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring  (28)
  • 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas  (13)
  • 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks  (9)
  • 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques  (8)
  • 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions  (7)
  • Acoustics
  • Applied geophysics
  • Data analysis / ~ processing
  • Fluids
  • Schussler
  • Textbook of geophysics
  • Elsevier  (44)
  • Cambridge U. Press
  • Cambridge Univ. Press
  • Geologica Society of America
  • Soc. of Exploration Geophys.
  • Wiley
  • 2010-2014  (10)
  • 2005-2009  (35)
  • 2000-2004
  • 1910-1914
  • 2012  (10)
  • 2005  (35)
Collection
Keywords
Publisher
Years
  • 2010-2014  (10)
  • 2005-2009  (35)
  • 2000-2004
  • 1910-1914
Year
  • 1
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    Acoustic and Elastic Wave Fields in Geophysics, III (2005)
    Elsevier
    In:  Amsterdam, 652 pp., Elsevier, vol. 39, no. XVI:, pp. 227-235, (0-444-51955-6)
    Details
    Publication Date: 2005
    Keywords: Seismics (controlled source seismology) ; Applied geophysics ; Wave propagation ; plane ; spherical ; and ; cylindrical ; Waves ; in ; isotropic ; and ; transversely ; isotropic ; solids, ; liquid-solid ; models, ; and ; media ; with ; cylindrical ; inclusions ; (boreholes) ; Textbook of geophysics
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    BIBLIOGRAPHY SEISMOLOGY
  • 2
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    Helium–strontium isotope constraints on mantle evolution beneath the Roman Comagmatic Province, Italy (2005)
    Elsevier
    Details
    Publication Date: 2020-12-03
    Description: A study of the He isotopic ratios of fluid inclusions in olivine and pyroxene from the Roman Comagmatic Province (RCP),Italy, is presented together with 87Sr/86Sr isotope compositions of the whole rock or pyroxene phenocrysts. A clear covariation in He and Sr isotopes is apparent, with a strong northward increase in radiogenic He and Sr being evident. He and Sr isotopes ratios range from 3He/4He = 5.2 Ra and 87Sr/86Sr = 0.7056 in south Campania, to 3He/4He = 0.44 Ra and 87Sr/86Sr = 0.715905 in the northernmost Latium. Helium isotope ratios are significantly lower than MORB values and are among the lowest yet measured in subduction zone volcanism. The 3He/4He of olivine and pyroxene phenocryst-hosted volatiles appear to be little influenced by posteruptive processes and magma–crust interaction. The 3He/4He–87Sr/86Sr covariation is consistent with binary mixing between an asthenospheric mantle similar to HIMU ocean island basalts, and an enriched (radiogenic) mantle end member generated from subduction of the Ionian/Adriatic plate. The contribution of radiogenic He from metasomatic fluids and postmetasomatism radiogenic ingrowth in the wedge is strongly dependent on the initial He concentration of the mantle. Only when asthenosphere He concentrations are substantially lower than the MORB source mantle, and metasomatism occurred at the beginning of the subduction (f30 Ma), can ingrowth in the mantle wedge account for the 3He/4He of the most radiogenic basalts.
    Description: - European Social Fund - Scottish Universities - Carnegie Trust for the Universities of Scotland.
    Description: Published
    Description: 295–308
    Description: partially_open
    Keywords: Roman Comagmatic Province ; fluid inclusions ; helium ; strontium ; 04. Solid Earth::04.01. Earth Interior::04.01.03. Mantle and Core dynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes ; 04. Solid Earth::04.07. Tectonophysics::04.07.08. Volcanic arcs ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
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  • 3
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    Carbonate-derived CO2 purging magma at depth: Influence on the eruptive activity of Somma-Vesuvius, Italy (2012)
    Elsevier
    Details
    Publication Date: 2020-11-30
    Description: Mafic phenocrysts from selected products of the last 4 ka volcanic activity at Mt. Vesuvius were investigated for their chemical and O-isotope composition, as a proxy for primary magmas feeding the system. 18O/16O ratios of studied Mg-rich olivines suggest that near-primary shoshonitic to tephritic melts experienced a flux of sedimentary carbonate-derived CO2, representing the early process of magma contamination in the roots of the volcanic structure. Bulk carbonate assimilation (physical digestion) mainly occurred in the shallow crust, strongly influencing magma chamber evolution. On a petrological and geochemical basis the effects of bulk sedimentary carbonate digestion on the chemical composition of the near-primary melts are resolved from those of carbonate-released CO2 fluxed into magma. An important outcome of this process lies in the effect of external CO2 in changing the overall volatile solubility of the magma, enhancing the ability of Vesuvius mafic magmas to rapidly rise and explosively erupt at the surface.
    Description: Published
    Description: 84-95
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: JCR Journal
    Description: reserved
    Keywords: stable-isotope ; magma geochemistry ; CO2-degassing ; Vesuvius ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
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  • 4
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    Dynamics of magma ascent and fragmentation in trachytic versus rhyolitic eruptions (2005)
    Elsevier
    Details
    Publication Date: 2020-10-29
    Description: We have performed a parametric study on the dynamics of trachytic (alkaline) versus rhyolitic (calc-alkaline) eruptions by employing a steady, isothermal, multiphase non-equilibrium model of conduit flow and fragmentation. The employed compositions correspond to a typical rhyolite and to trachytic liquids from Phlegrean Fields eruptions, for which detailed viscosity measurements have been performed. The investigated conditions include conduit diameters in the range 30–90 m and total water contents from 2 to 6 wt%, corresponding to mass flow rates in the range 106–108 kg/s. The numerical results show that rhyolites fragment deep in the conduit and at a gas volume fraction ranging from 0.64 to 0.76, while for trachytes fragmentation is found to occur at much shallower levels and higher vesicularities (0.81–0.85). An unexpected result is that low-viscosity trachytes can be associated with lower mass flow rates with respect to more viscous rhyolites. This is due to the non-linear combined effects of viscosity and water solubility affecting the whole eruption dynamics. The lower viscosity of trachytes, together with higher water solubility, results in delayed fragmentation, or in a longer bubbly flow region within the conduit where viscous forces are dominant. Therefore, the total dissipation due to viscous forces can be higher for the less viscous trachytic magma, depending on the specific conditions and trachytic composition employed. The fragmentation conditions determined through the simulations agree with measured vesicularities in natural pumice clasts of both magma compositions. In fact, vesicularities average 0.80 in pumice from alkaline eruptions at Phlegrean Fields, while they tend to be lower in most calc-alkaline pumices. The results of numerical simulations suggest that higher vesicularities in alkaline products are related to delayed fragmentation of magmas with this composition. Despite large differences in the distribution of flow variables which occur in the deep conduit region and at fragmentation, the flow dynamics of rhyolites and trachytes in the upper conduit and at the vent can be very similar, at equal conduit size and total water content. This is consistent with similar phenomenologies of eruptions associated with the two magma types.
    Description: Published
    Description: 93-108
    Description: partially_open
    Keywords: trachytic magma ; conduit flow ; eruption dynamics and numerical simulations ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 5
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    The age of the Neapolitan Yellow Tu caldera-forming eruption (Campi Flegrei caldera-Italy) assessed by 40Ar/39Ar dating method (2005)
    Elsevier
    Details
    Publication Date: 2020-12-17
    Description: The Neapolitan Yellow Tuff (NYT) is the product of the largest known trachytic phreatoplinian eruption. It covered an area larger than 1000 km2 with an estimated volume of about 40 km3 of erupted magma. During the course of the eruption a caldera collapsed within the previously formed Campanian Ignimbrite caldera. The resulting nested structure strongly influenced the following volcanic activity in the Campi Flegrei caldera. As previous dating of the NYT does not converge toward a unique result, a new set of 40Ar/39Ar age determinations has been carried out to better constrain the age of the eruption. Two variants of the 40Ar/39Ar dating method were applied to determine the age of the NYT eruption: (1) single-crystal total fusion (SCTF), on an individual phenocryst of feldspar, and (2) laser incremental heating (LIH), on bulk aliquots of feldspar phenocrysts. The results of the SCTF analyses show that the overall sample weighted mean age, derived from the conventional age calculation, is 15.6 ;0.8 ka. A weighted mean of the isochron age is 15.3 ;1.2 ka (2c), and has been assumed as the best indicator of age to be derived from the SCTF analyses. The LIH analyses results show that plateau ages vary from 15.4; 0.5 to 14.5; 0.5 ka. The overall weighted mean age of the isochron results is 14.9;0.4 ka (2c). This result has been assumed as the reference age for the NYT eruption, and agrees with the SCTF age. The new age obtained for the NYT deposits is of great relevance for the understanding of the evolution and the present state of the Campi Flegrei caldera and collocates the NYT in a crucial stratigraphical position to date the climatic oscillations that occurred between the Late Glacial and the Holocene.
    Description: Published
    Description: 157-170
    Description: partially_open
    Keywords: Neapolitan Yellow Tuff ; Campi Flegrei caldera ; 40Ar/39Ar dating method ; Geochronology ; Late Glacial ; Holocene ; 04. Solid Earth::04.04. Geology::04.04.02. Geochronology ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 6
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    Magma-derived gas influx and water-rock interactions in the volcanic aquifer of Mt. Vesuvius, Italy (2005)
    Elsevier
    Details
    Publication Date: 2021-06-25
    Description: We report in this paper a systematic investigation of the chemical and isotopic composition of groundwaters flowing in the volcanic aquifer of Mt. Vesuvius during its current phase of dormancy, including the first data on dissolved helium isotope composition and tritium content. The relevant results on dissolved He and C presented in this paper reveal that an extensive interaction between rising magmatic volatiles and groundwaters currently takes place at Vesuvius. Vesuvius groundwaters are dilute (mean TDS 2800 mg/L) hypothermal fluids (mean T 17.7°C) with a prevalent alkaline-bicarbonate composition. Calcium-bicarbonate groundwaters normally occur on the surrounding Campanian Plain, likely recharged from the Apennines. D and 18O data evidence an essentially meteoric origin of Vesuvius groundwaters, the contribution from either Tyrrhenian seawater or 18O-enriched thermal water appearing to be small or negligible. However, the dissolution of CO2-rich gases at depth promotes acid alteration and isochemical leaching of the permeable volcanic rocks, which explains the generally low pH and high total carbon content of waters. Attainment of chemical equilibrium between the rock and the weathering solutions is prevented by commonly low temperature (10 to 28°C) and acid-reducing conditions. The chemical and isotope (C and He) composition of dissolved gases highlights the magmatic origin of the gas phase feeding the aquifer. We show that although the pristine magmatic composition may vary upon gas ascent because of either dilution by a soil-atmospheric component or fractionation processes during interaction with the aquifer, both 13C/12C and 3He/4He measurements indicate the contribution of a magmatic component with a 13C 0‰ and R/Ra of 2.7, which is consistent with data from Vesuvius fumaroles and phenocryst melt inclusions in olivine phenocrysts. A main control of tectonics on gas ascent is revealed by data presented in this paper. For example, two areas of high CO2 release and enhanced rock leaching are recognized on the western (Torre del Greco) and southwestern (Torre Annunziata–Pompeii) flanks of Vesuvius, where important NE-SW and NW-SE tectonic structures are recognized. In contrast, waters flowing through the northern sector of the volcano are generally colder, less saline, and CO2 depleted, despite in some cases containing significant concentrations of magmaderived helium. The remarkable differences among the various sectors of the volcano are reconciled in a geochemical interpretative model, which is consistent with recent structural and geophysical evidences on the structure of Somma-Vesuvius volcanic complex.
    Description: -European Union, -Ministero dell’Universita’ e della Ricerca Scientifica e Tecnologica; -CNR–Gruppo Nazionale per la Vulcanologia.
    Description: Published
    Description: 963–981
    Description: partially_open
    Keywords: isotopes ; water chemistry ; dissolved gases ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 03. Hydrosphere::03.04. Chemical and biological::03.04.07. Radioactivity and isotopes ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 7
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    Geochemical monitoring of groundwaters (1998-2001) at Vesuvius volcano (Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: This work presents the results of hydrogeochemical studies carried out at Vesuvius during the period May 1998 - December 2001, mostly focusing on compositional time variations observed during this time. Based on their chemistry, groundwater samples are distinguished into two groups, 1 and 2, representative of water circulation in the southern and northern sectors of the volcano, respectively. Waters from group 1 are typically more acidic, warmer,and more saline than those of group 2. They also have higher CO2 and CH4 contents, attributed to enhanced input of deep-rising volatiles and prolonged water-rock interactions. Time-series highlight the fairly constant chemical composition of the entire aquifer. Groundwater temperature, pH, bicarbonate content and dissolved CO2 display quite stable values in the study period, particularly in deep wells (piezometric level more than 100 m deep). Shallower water bodies present more evident temporal variations, related to seasonal and anthropogenic effects. This paper also describes some important variations in water chemistry which had occurred by the time of the seismic event in early October 1999, particularly in the Olivella spring located on the northern flank of the volcano. At this site, a great decrease in water pH and redox potential, and increased dissolved CO2 contents and 3He/4He ratios were observed. These changes in chemical and isotope composition support the hypothesis of an input of magma-derived helium and carbon dioxide into the aquifer feeding the Olivella spring by the time of the earthquake.
    Description: Published
    Description: 81-104
    Description: partially_open
    Keywords: Vesuvius ; volcanic surveillance ; groundwater ; hydro-geochemistry ; oxygen-18 ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 8
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    Water speciation and Sr isotopic exchange during water-melt interaction: a combined NMR-TIMS study on the Cretaio Tephra (Ischia Island,south Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: In order to improve the microscopic understanding of the water-magma interaction process during explosive volcanism,volcanic glasses representative of deposits with sedimentological characteristics suggesting different water/melt ratios were studied by a combination of the nuclear magnetic resonance (NMR) and TIMS methods. The glasses were separated from pumices of two surge layers and one fallout bed of the Cretaio Tephra (Ischia Island,Italy), which is the product of an explosive eruption that occurred at Ischia in the second century BC. The 29Si CP^MAS NMR experiments indicate the occurrence of 1H^29Si dipolar couplings in glasses from the phreatomagmatic activity, suggesting the presence of hydrogen atoms in proximity of silicon atoms. This feature is not detected in the glass from the deposit of the magmatic explosion. 1H MAS NMR spectra reveal different peaks attributed to different hydrous species characterized by different motional properties. These include ‘rigid’ H2O groups isolated in the glass structure, more mobile water species and possibly structural hydroxyl groups. 1H MAS NMR spectra recorded after deuteration experiments of the glass at a temperature up to 300‡C revealed that the exchange reactions of the D2O vapor with hydrogen were limited to the most mobile water species,possibly on vesicle surfaces or in channels. The hydrogen concentration linearly correlates with the 87Sr/86Sr isotope ratio in glasses,suggesting isotopic tracer exchanges between the Sr dissolved in the water vapor and the Sr in the silicon-oxygen network during hydration. It is proposed that the uprising melt interacted with a hydrothermal system of seawater-derived fluids,characterized by relatively high Sr isotopic composition.
    Description: Published
    Description: 311-320
    Description: partially_open
    Keywords: Ischia ; Cretaio Tephra ; Water-melt interaction ; Nuclear magnetic resonance ; Sr isotopes ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 9
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    Thermal and geochemical constraints on the ‘deep’ magmatic structure of Mt. Vesuvius (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A review of available and new isotopic data on rocks from Mt. Vesuvius together with geophysical and mineralogical data allow us to define a ‘deep’ complex magmatic reservoir where mantle-derived magmas arrive, stagnate and differentiate, and to constrain a thermal model, which describes the history and present state of the reservoir and its surrounding rocks. The top of the reservoir is located at about 8 km depth, and it extends discontinuously down to 20 km depth. The reservoir is hosted in densely fractured continental crustal rocks, where magmas and crust can interact, and, according to thermal modeling results, has been fed more than once in the last 400 ka. The hypothesis of crustal contamination is favored by the high temperatures reached by crustal rocks as a consequence of repetitive intrusions of magma. From the ‘deep’ reservoir magmas rise to form ‘shallow’ magma chambers at different depths, as already known in the literature, where they can undergo low-pressure differentiation and mixing and feed the volcanic activity.
    Description: Published
    Description: 1-12
    Description: partially_open
    Keywords: Magmatic system ; Crustal contamination ; Thermal modeling ; Isotope geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
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    Plume chemistry provides insights into mechanisms of sulfur and halogen degassing in basaltic volcanoes (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: This paper deals with sulfur, chlorine and fluorine abundances in the eruptive volcanic plume of the huge October 2002– January 2003 eruption of Mount Etna, aiming at relating the relevant compositional variations observed throughout with changes in eruption dynamics and degassing mechanisms. The recurrent sampling of plume acidic volatiles by filter-pack methodology revealed that, during the study period, S/Cl and Cl/F ratios ranged from 0.1–6.8 and 0.9–5.6, respectively. Plume S/Cl ratios increased by a factor of f10 as volcanic activity drifted from paroxysmal lava fountaining (mid- and late November) to passive degassing and minor effusion (early January), and then decreased to the low values (S/Cl = 0.1) typical of the final stages of the eruption. Parallel variations in chlorine to fluorine ratios were also observed. A theoretical model is proposed for quantitative interpretation of these changes in plume composition. The model calculates the composition of a volatile phase exsolving from an ascending Etna magma, based on knowledge of solubilities and abundances in the undegassed melt of sulfur and halogens [T.M. Gerlach, EOS 72 (1991), 249, 254–255]. According to this model, degassing of Etnean basaltic melt at high pressures and depths (〉100 MPa, 3 km) is likely to release a CO2+H2O-rich vapor phase with S/Cl molar ratios f1. Extensive sulfur and chlorine degassing from the melt would take place at shallower depth ( P 〈 20 MPa, 0.6 km), with S/Cl ratios in the vapor phase increasing as pressure drops to 0.1 MPa. Comparisons between model compositions and volcanic plume data demonstrate that the chemical trends observed during the eruption may be explained by increased degassing due to depressurization of a basaltic magma batch ascending toward the surface.
    Description: Published
    Description: 469-483
    Description: partially_open
    Keywords: magmatic degassing ; volcanic plume ; basaltic eruption ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 11
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    Rapid morphological changes at the summit of an active volcano: reappraisal of the poorly documented 1964 eruption of Mount Etna (Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: While the eruptive record of Mount Etna is reasonably complete for the past 400 years, the activity of the early and late 1960s, which took place at the summit, is poorly documented in the scientific literature. From 1955 to 1971, the Central and Northeast Craters were the sites of long-lived mild Strombolian and effusive activity, and numerous brief episodes of vigorous eruptive activity, which led to repeated overflows of lava onto the external flanks of the volcano. A reconstruction of the sequence of the more important of these events based on research in largely obscure and nearly inaccessible sources permits a better understanding of the eruption dynamics and rough estimates of erupted volumes and of the changes to the morphology of the summit area. During the first half of 1964, the activity culminated in a series of highly dynamic events at the Central Crater including the opening of a fissure on the E flank of the central summit cone, lava fountains, voluminous tephra emission, prolonged strong activity with continuous lava overflows, and growth of large pyroclastic intracrater cones. Among the most notable processes during this eruption was the breaching of a section of the crater wall, which was caused by lateral pressure of lava ponding within the crater. Comparison with the apparently similar summit activity of 1999 allows us to state that (a) lava overflows from large pit craters at the summit are often accompanied by breaching of the crater walls, which represents a significant hazard to nearby observers, and that (b) eruptive activity in 1999 was much more complex and voluminous than in 1964. For 1960s standards however, the 1964 activity was the most important summit eruption in terms of intensity and output rates for about 100 years, causing profound changes to the summit morphology and obliterating definitively the former Central Crater.
    Description: Published
    Description: 203-218
    Description: partially_open
    Keywords: Mount Etna ; Summit eruption ; Crater morphology and Lava overflows ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 12
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    Fluctuation analysis of the hourly time variability of volcano-magnetic signals recorded at Mt. Etna Volcano, Sicily (Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The time-correlation properties in the hourly time variability of volcano-magnetic data measured at the active volcano Mt. Etna, Sicily (southern Italy), are investigated by using the detrended fluctuation analysis (DFA). DFA is a data processing method that allows for the detection of scaling behaviors in observational time series even in the presence of nonstationarities. The procedure adopted has revealed unambiguous link between the dynamics of the measured data and the recent eruptive episode of the volcano occurred on October 27, 2002.
    Description: Published
    Description: 1921-1929
    Description: partially_open
    Keywords: MT Etna ; 04. Solid Earth::04.05. Geomagnetism::04.05.04. Magnetic anomalies ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 13
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    Seismoacoustic measurements during the July–August 2001 eruption of Mt. Etna volcano, Italy (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: On July 18, 2001, two main eruptive vents opened on the southern flank of Mount Etna volcano (Italy) at ~2100 m and ~2550 m a.s.l., respectively. The former vent fed mild strombolian activity and lava flows, while the latter represented the main explosive vent, producing strong phreato-magmatic explosions. Explosions at this latter vent, however, shifted to a strombolian style in the following days, before switching back to phreato-magmatic activity towards the end of the eruption, which ended on August 9, 2001. On August 3, a small seismoacoustic array was deployed close to the eruptive vents. The array was composed of three stations, which recorded seismic and infrasonic waves coming from both of the eruptive vents. A further seismoacoustic station, equipped with a thermal-infrared sensor, was also installed several kilometers north of the first array. Seismic signals relating to the strombolian activity at the 2100-m vent were characterized by a strong decompression at the source. Analysis of the time delays between seismic, infrasonic and infrared event onsets also revealed that ejection velocities during explosions from both vents were subsonic. Time delays between the onset of explosive events apparent in the infrared and infrasound data indicated that the explosion source at the 2550-m vent was located 220–250 m below the crater rim. In comparison, the depth of the seismic source was estimated to be between 230 and 335 m below the rim. This converts to 120–150 and 130–235 m below the preexisting ground surface. In addition, time delays between seismic and infrasonic signals recorded for the lower (2100 m) vent also revealed a seismic source that was no more than a few tens of meters deeper than the fragmentation surface.
    Description: Published
    Description: 219-230
    Description: partially_open
    Keywords: Mt. Etna ; explosive eruptions ; arrays ; seismic ; infrasonic and thermal data ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 14
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    Pulsed lava effusion at Mount Etna during 2001 (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Effusion rate and degassing data collected at Mt. Etna volcano (Italy) in 2001 show variations occurring on time scales of hours to months. We use both long- and short-term data sets spanning January to August to identify this variation. The long data sets comprise a satellite- and ground-based time series of effusion rates, and the latter include field-based effusion rate and degassing data collected May 29–31. The satellite-derived effusion rates for January through August reveal four volumetric pulses that are characterized by increasing mean effusion rate values and lead up to the 2001 flank eruption. Peak effusion rates during these 23–57 day pulses were 1.2 m3 s-1 in Pulse 1 (1 Jan–4 Mar), 1.1 m3 s-1 in Pulse 2 (5 Mar–21 Apr), 4.2 m3 s-1 in Pulse 3 (24 Apr–18 Jun), 8.8 m3 s-1 in Pulse 4 (23 Jun–16 Jul), and 22.2 m3 s-1 during the flank eruption (17 Jul–9 Aug). Rank-order analysis of the satellite data shows that effusion rate values during the 2001 flank eruption define a statistically different trend than Etna's persistent activity from Jan 1 to Jul 17. Data prior to the flank eruption obey a power-law relationship that may define an effusion rate threshold of ~3–5 m3 s-1 for Etna's typical persistent activity. Our short-term data coincide with the satellite-derived peak effusion period of Pulse 3. Degassing (at-vent puff frequency) shows a general increase from May 29 to 31, with hour-long variations in both puff frequency and lava flow velocity (effusion rate). We identify five 3–14 h degassing periods that contain 26 shorter (19–126 min-long) oscillations. This variation shows some positive correlation with effusion rate measurements during the same time period. If a relationship between puff frequency and effusion rate is valid, we propose that their short-term variation is the result of changes in the supply rate of magma to the near-vent conduit system. Therefore, these short-term data provide some evidence that the clear weeks- to months-long variation in Etna's effusive activity (January–August 2001) was overprinted by a minutes- to hour-scale oscillation in shallow supply.
    Description: Published
    Description: 231-246
    Description: partially_open
    Keywords: effusion rate ; degassing ; oscillation ; shallow supply and Etna ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 15
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    H2S fluxes from Mt. Etna, Stromboli, and Vulcano (Italy) and implications for the sulfur budget at volcanoes (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We present here new measurements of sulfur dioxide and hydrogen sulfide emissions from Vulcano, Etna, and Stromboli (Italy), made by direct sampling at vents and by filter pack and ultraviolet spectroscopy in downwind plumes. Measurements at the F0 and FA fumaroles on Vulcano yielded SO2/H2S molar ratios of 0.38 and 1.4, respectively, from which we estimate an H2S flux of 6 to 9 for the summit crater. For Mt. Etna and Stromboli, we found SO2/H2S molar ratios of 20 and 15, respectively, which combined with SO2 flux measurements, suggest H2S emission rates of 50 to 113 and 4 to 8, respectively. We observe that source and plume SO2/H2S ratios at Vulcano are similar, suggesting that hydrogen sulfide is essentially inert on timescales of seconds to minutes. This finding has important implications for estimates of volcanic total sulfur budget at volcanoes since most existing measurements do not account for H2S emission.
    Description: Published
    Description: 1861–1871
    Description: partially_open
    Keywords: H2S atmospheric budget ; volcanic degassing ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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  • 16
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    Changes in fluid geochemistry and physico-chemical conditions of geothermal systems caused by magmatic input: The recent abrupt outgassing off the island of Panarea (Aeolian Islands, Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Hydrothermal systems and related vents can exhibit dramatic changes in their physico-chemical conditions over time as a response to varying activity in the feeding magmatic systems. Massive steam condensation and gas scrubbing processes of thermal fluids during their ascent and cooling cause further compositional changes that mask information regarding the conditions evolving at depth in the hydrothermal system. Here we propose a new stability diagram based on the CO2-CH4-CO-H2 concentrations in vapor, which aims at calculating the temperatures and pressures in hydrothermal reservoirs. To filter gas scrubbing effects, we have also developed a model for selective dissolution of CO2-H2S-N2-CH4-He-Ne mixtures in fresh and/or air-saturated seawater. This methodology has been applied to the recent (November 2002) crisis that affected the geothermal field off the island of Panarea (Italy), where the fluid composition and fluxes have been monitored for the past two decades. The chemical and isotopic compositions of the gases suggest that the volatile elements originate from an active magma, which feeds a boiling saline solution having temperatures of up to 350 C and containing 12 mol CO2 in vapor. The thermal fluids undergo cooling and re-equilibration processes on account of gas-water-rock interactions during their ascent along fracture networks. Furthermore, steam condensation and removal of acidic species, partial dissolution in cold air-saturated seawater and stripping of atmospheric components, affect the composition of the geothermal gases at shallow levels. The observed geochemical variations are consistent with a new input of magmatic fluids that perturbed the geothermal system and caused the unrest event. The present-state evolution shows that this dramatic input of fluids is probably over, and that the system is now tending towards steady-state conditions on a time scale of months.
    Description: Published
    Description: 3045-3059
    Description: partially_open
    Keywords: Submarine degassing ; geothermal system ; gas-water interaction ; gas geothermometry ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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  • 17
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    Gas hazard assessment in a densely inhabited area of Colli Albani Volcano (Cava dei Selci, Roma) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The northwestern flank of the Colli Albani, a Quaternary volcanic complex near Rome, is characterised by high CO2 values and Rn activities in the groundwater and by the presence of zones with strong emission of gas from the soil. The most significant of these zones is Cava dei Selci where many houses are located very near to the gas emission site. The emitted gas consists mainly of CO2 (up to 98 vol) with an appreciable content of H2S (0.8). The He and C isotopic composition indicates, as for all fluids associated with the Quaternary Roman and Tuscany volcanic provinces, the presence of an upper mantle component contaminated by crustal fluids associated with subducted sediments and carbonates. An advective CO2 flux of 37 tons/day has been estimated from the gas bubbles rising to the surface in a small drainage ditch and through a stagnant water pool, present in the rainy season in a topographically low central part of the area. A CO2 soil flux survey with an accumulation chamber, carried out in February-March 2000 over a 12 000 m2 surface with 242 measurement points, gave a total (mostly conductive) flux of 61 tons/day. CO2 soil flux values vary by four orders of magnitude over a 160-m distance and by one order of magnitude over several metres. A fixed network of 114 points over 6350 m2 has been installed in order to investigate temporal flux variations. Six surveys carried out from May 2000 to June 2001 have shown large variations of the total CO2 soil flux (8/25 tons/day). The strong emission of CO2 and H2S, which are gases denser than air, produces dangerous accumulations in low areas which have caused a series of lethal accidents to animals and one to a man. The gas hazard near the houses has been assessed by continuously monitoring the CO2 and H2S concentration in the air at 75 cm from the ground by means of two automatic stations. Certain environmental parameters (wind direction and speed; atm P, T, humidity and rainfall) were also continuously recorded. At both stations, H2S and CO2 exceeded by several times the recommended concentration thresholds. The highest CO2 and H2S values were recorded always with wind speeds less than 1.5 m/s, mostly in the night hours. Our results indicate that there is a severe gas hazard for people living near the gas emission site of Cava dei Selci, and appropriate precautionary and prevention measures have been recommended both to residents and local authorities.
    Description: - GNV funded research project Gas Hazard of Colli Albani
    Description: Published
    Description: 81^94
    Description: partially_open
    Keywords: Colli Albani ; CO2 flux ; H2S ; gas hazard ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 18
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    Birth, growth and morphologic evolution of the `Laghetto´ cinder cone during the 2001 Etna eruption (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We have undertaken detailed observations of the formation of the `Laghetto´ cinder cone, a new cone that formed during a 2-week period of intense activity in Piano del Lago, on the upper slopes of Mount Etna in summer 2001. We describe the events leading to the formation of a small graben, the formation of pit craters on the base of the graben, the onset of phreatomagmatic activity, a transition to intense Strombolian activity, and a return to phreatomagmatic activity as the eruption came to an end. We discuss the reasons for these transitions, and describe the morphological development of the cone during these events. Arcuate cracks on the southern part of the cone were related to withdrawal of magma at the end of the eruption. Other slope instabilities that developed during the eruption include the formation of small radial grain flows on the outer flanks of the cone and the collapse into the crater of part of the crater rim. Some of the failure planes we observed were first identified using a FLIR TM 695 thermal infrared camera. This is the first time that infrared thermography has been used to detect instability of volcanic structures. Results obtained during this test case demonstrate that thermal cameras are a very useful tool for studies of volcanic instability.
    Description: Published
    Description: 225-239
    Description: partially_open
    Keywords: Etna volcano ; cinder cone ; volcano instability ; thermal images ; phreatomagmatic activity ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 19
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    The influence of conduit processes on changes in style of basaltic Plinian eruptions: Tarawera 1886 and Etna 122 BC (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Basaltic volcanism is most typically thought to produce effusion of lava, with the most explosive manifestations ranging from mild Strombolian activity to more energetic fire fountain eruptions. However, some basaltic eruptions are now recognized as extremely violent, i.e., generating widespread phreatomagmatic, subplinian and Plinian fall deposits. We focus here on the influence of conduit processes, especially partial open-system degassing, in triggering abrupt changes in style and intensity that occurred during two examples of basaltic Plinian volcanism. We use the 1886 eruption of Tarawera, New Zealand, the youngest known basaltic Plinian eruption and the only one for which there are detailed written eyewitness accounts, and the well-documented 122 BC eruption of Mount Etna, Italy, and present new grain size and vesicularity data from the proximal deposits. These data show that even during extremely powerful basaltic eruptions, conduit processes play a critical role in modifying the form of the eruptions. Even with very high discharge, and presumably ascent, rates, partial open-system behaviour of basaltic melts becomes a critical factor that leads to development of domains of largely stagnant and outgassed melt that restricts the effective radius of the conduit. The exact path taken in the waning stages of the eruptions varied, in response to factors which included conduit geometry, efficiency and extent of outgassing and availability of ground water, but a relatively abrupt cessation to sustained high-intensity discharge was an inevitable consequence of the degassing processes.
    Description: Published
    Description: 1-14
    Description: partially_open
    Keywords: basaltic Plinian eruption ; Etna ; Tarawera and explosive volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 20
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    Volcanomagnetic changes accompanying the onset of the 2002–2003 eruption of Mt. Etna (Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-03
    Description: Remarkable changes in the local magnetic field were associated with the onset of the 2002–2003 flank eruption at Mt. Etna. After differential magnetic field measurements were filtered from the external noise by using adaptive filters, we recognized two stages in the total intensity changes, which are closely related to different volcanic events: (a) rapid variations of about 4–5 nT associated with October 26 seismic swarm recorded beneath the summit craters; (b) step-like variations of 9–10 nT coincident with October 27 eruptive fissures opening up in the north flank. These observations are generally consistent with those calculated from simple magnetic models of these volcanic processes, in which the magnetic changes are generated by stress redistribution due to magmatic intrusions at different depth. The magnetic data not only allow the timing of the intrusive event to be described in greater detail but also, together with other volcanological and geophysical evidences, permit some constraints to be set on the characteristics of propagation of a shallow dike. Firstly, at around midnight on 26 October magma was rapidly injected to a depth of 3–4 km just below the summit craters. Secondly, after 1:00 on 27 October, continued intrusion magma occurred upward and culminated a few hundred meters below the free surface fractured along a N–E direction. Thirdly, at about 2:28, magma gave rise to an explosive fissural vent at the northern base of the NE crater near 3000 m a.s.l. Finally, at about 5:00, the first eruptive fissure became active along the eastern border of the NE rift at 2500 m a.s.l. The rate of growth of the magnetic anomalies, moreover, leads to the interpretation that the magmatic intrusion travelled northward from base of the NE crater to the NE rift at approximately 14 m/min.
    Description: Published
    Description: 1-14
    Description: partially_open
    Keywords: eruptions ; monitoring ; magnetic methods ; volcanomagnetic modeling ; Mt. Etna ; 04. Solid Earth::04.05. Geomagnetism::04.05.04. Magnetic anomalies ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 21
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    The buried caldera of Misti volcano, Peru, revealed by combining a self-potential survey with elliptic Fourier function analysis of topography (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: This survey proposes a new approach to identify buried caldera boundaries of a volcanic cone, combining (1) a systematic elliptic Fourier functions (EFF) analysis on the contour lines based on the external shape of the edifice with (2) self-potential (SP) measurements on volcano flanks. The methodology of this approach is to investigate the relationships between (1) vertical morphological changes inferred from EFF analysis and (2) lateral lithological transition inside the edifice inferred from SP/elevation gradients. The application of these methods on Misti volcano in southern Peru displays a very good correlation. The three main boundaries evidenced by hierarchical cluster analysis on the contour lines coincide with the two main boundaries characterised by SP signal and with a secondary SP signature related with a summit caldera. In order to explain these results showing a very good correlation between morphologic and lithologic changes as function of elevation, caldera boundaries have been suggested. The latter would be located at an average elevation of (1) 4350–4400 m, (2) 4950–5000 m, and (3) 5500– 5550 m. For the lowest boundary in elevation, the coincidence with the lateral extension of the hydrothermal system inferred from SP measurements suggests that caldera walls act as a barrier for lateral extension of hydrothermal systems. In the summit area, the highest boundary has been related with the summit caldera, inferred by a secondary SP minimum and geological evidence.
    Description: - Institut de Recherche pour le Développement (IRD) - Instituto Geofisico del Peru´ (IGP).
    Description: Published
    Description: 283– 297
    Description: partially_open
    Keywords: caldera ; elliptic Fourier functions ; geomorphology ; self-potential ; Misti volcano ; Peru ; 03. Hydrosphere::03.02. Hydrology::03.02.02. Hydrological processes: interaction, transport, dynamics ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.02. Exploration geophysics::04.02.04. Magnetic and electrical methods ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 05. General::05.02. Data dissemination::05.02.04. Hydrogeological data ; 05. General::05.05. Mathematical geophysics::05.05.99. General or miscellaneous ; 05. General::05.08. Risk::05.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 22
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    2001 flank eruption of the alkali- and volatile-rich primitive basalt responsible for Mount Etna's evolution in the last three decades (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Since the early 1970s enhanced eruptive activity of Mount Etna has been accompanied by selective geochemical changes in erupted lavas, among which a gradual increase of alkalis whose origin is still debated. Here we provide further insight into the origin of this recent evolution, based on a detailed study of the chemistry and dissolved volatile content of melt inclusions trapped in olivine crystals of unusual plagioclase-poor primitive basalt that was extruded during a highly explosive flank eruption in July–August 2001. Two types of lava were erupted simultaneously along a N–S fracture system. Trachybasalts from the upper vents (2950–2700 m) were simply drained out by fracturing of the central volcanic conduit. They are identical to summit crater lavas and contain Mg-poor olivines (Fo70–72) with evolved and volatile-poor melt inclusions that represent late-stage crystallisation during shallow open conduit degassing. In contrast, plagioclase-poor basalt (80% of total) extruded through the lower vents (2550–2100 m) derived from lateral dyke intrusion of a more primitive and volatile-rich magma across the sedimentary basement. This primitive melt is best preserved in rare Fo82.4–80.5 skeletal olivines present in lapilli deposits from the most powerful activities at the 2550 m vent. Its high dissolved contents of H2 O (3.4 wt.%), CO2 (0.11 to 0.41 wt.%), S (0.32 wt.%), Cl (0.16 wt.%) and F (0.094 wt.%) point to its closed system ascent from ∼400 to 250 MPa (∼12 to 6.5 km depth b.s.l.). However, the predominance of euhedral olivine phenocrysts with common reverse zoning (cores Fo76–78 and rims Fo78–80) and decrepited inclusions shows that most of the erupted basalt derived from a slightly more evolved, crystallizing body of the same magma that was invaded by the uprising primitive melt prior to erupting. The few preserved inclusions in these olivines indicate pre-eruptive storage of that magma body at about 5 km depth b.s.l., in coherence with seismic data. We propose that the 2001 flank eruption resulted from gradual overpressuring of Etna's shallow plumbing system due to the influx of volatile-rich primitive basalt that may have begun several months in advance. We find that this basalt is much richer in alkalis (2.0 wt.% K2 O) and has higher S/Cl (2.0) but lower Cl/K and Cl/F ratios than all pre-1970s Etnean lavas (1.4 wt.% K2 O, S/Cl=1.5), as further exemplified by melt inclusions in entrained olivine xenocrysts. Combining these new observations with previously published data, we argue that the 2001 basalt represents a new alkali-rich basic end-member feeding Mt. Etna, only few amount of which had previously been extruded during a 1974 peripheral eruption and, more recently, during brief paroxysmal summit events. Over the last three decades this new magma has progressively mixed with and replaced the former K-poorer trachybasalts filling the plumbing system, leading to extrusion of gradually more primitive and alkali-richer lavas. Its geochemical singularities cannot result from shallow crustal contaminations. Instead, they suggest the involvement of an alkali-richer but Cl-poorer arc-type component during recent magma genesis beneath Etna.
    Description: Published
    Description: 1-17
    Description: partially_open
    Keywords: Mt. Etna ; volatiles ; degassing ; eruptive mechanism ; magma geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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  • 23
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    Development of tumuli in the medial portion of the 1983 aa flow-field, Mount Etna, Sicily (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A number of tumuli formed on the aa-dominated lava fan complex which developed in the medial zone of the 1983 flow-field of Mount Etna during the later stages of the eruption. This complex flow-field formed on shallow sloping ground below a scarp between 1900 and 1700 m asl. A major tube system fed a branching tube network in the fan complex. Numerous tumuli and break-outs of lava formed in the fan. Three main types of tumulus are identified: (1) Focal tumuli, which are formed from the break-up and uplift of `old´, thick lava crust and themselves become sustained sites for the distribution of lava both as flows and within distributary tubes. These focal tumuli are significant centres associated with major tubes. (2) Satellite tumuli, which are typically elongate, whale-back shaped features that branch out from focal tumuli. These satellite tumuli were initially lava flows erupted from a focal tumulus. The crust of the flow slowed or came to a halt and the rigid crust became uplifted and fractured, forming a dome-shaped ridge feature. These satellite tumuli continued to be fed from the focal tumulus and became sites of lava emission with numerous break-outs. (3) Distributary tumuli formed on the fan associated with short-lived break-outs from tubes and are relatively simple structures formed from limited effusion of toey lobes and pahoehoe lava. The major tumuli on the fan complex show distinct dilation fractures. The fracture surfaces provide good exposure of the crust and three distinct zones are recognised – an upper zone showing columnar jointing, a middle zone consisting of planar fracture surfaces and a basal zone with distinctive banded planar fracture surfaces showing evidence of both brittle and ductile formation. Using these data a model is proposed for tumulus growth. Field analysis of the fan complex shows how it was fed by a branching tube system, leading to flow thickening, formation of tumuli and numerous ephemeral boccas.
    Description: Published
    Description: partially_open
    Keywords: aa lava flow-field ; Mount Etna ; tumulus ; lava crust and lava tubes. ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 24
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    Unusual sedimentary deposits on the SE side of Stromboli volcano, Italy: products of a tsunami caused by the ca. 5000 years BP Sciara del Fuoco collapse? (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The role of sector collapse in the generation of catastrophic volcanigenic tsunami has become well understood only recently, in part because of the problems in the preservation and recognition of tsunami deposits. Tinti et al. [Tinti, S., Bortolucci, E., Romagnoli, C., 2000. Computer simulations of tsunamis due to sector collapse at Stromboli, Italy. J. Volcanol. Geotherm. Res. 96, 103–128] modeled a tsunami produced by the c. 5,000 years BP collapse of the Sciara del Fuoco on the island volcano Stromboli. Although deposits associated with this event are generally lacking on the island, volcaniclastic breccias on the SE side of the island extending to an elevation above 120 m a.s.l. may have been generated by this tsunami. Deposits above 100 m are dominated by coarse breccias comprising disorganized, poorly sorted, nonbedded, angular to subangular lava blocks in a matrix of finer pyroclastic debris. These breccias are interpreted as a water-induced mass flow, possibly a noncohesive debris flow, generated as colluvial material on steep slopes was remobilized by the return flow of the tsunami wave, the run-up of which reached an elevation exceeding 120 m a.s.l. Finer breccias of subrounded to rounded lava blocks cropping out at 15 m a.s.l. are similar to modern high-energy beach deposits and are interpreted as beach material redeposited by the advancing tsunami wave. The location of these deposits matches the predicted location of the maximum tsunami wave amplitude as calculated by modeling studies of Tinti et al. [Tinti, S., Bortolucci, E., Romagnoli, C., 2000. Computer simulations of tsunamis due to sector collapse at Stromboli, Italy. J. Volcanol. Geotherm. Res. 96, 103–128]. Whereas the identification and modeling of paleo-tsunami events is typically based on the observation of the sedimentary deposits of the tsunami run-up, return flow may be equally or more important in controlling patterns of sedimentation.
    Description: Published
    Description: 329-340
    Description: partially_open
    Keywords: tsunami ; flank collapse ; landslide ; run-up ; return flow ; debris flow ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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    Genesis of chlorine and sulphur in fumarolic emissions at Vulcano Island (Italy) : assessment of pH and redox conditions in the hydrothermal system (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Chlorine- and sulphur-bearing compounds in fumarole discharges of the La Fossa crater at Vulcano Island (Italy) can be modelled by a mixing process between magmatic gases and vapour from a boiling hydrothermal system. This allows estimating the compounds in both endmembers. Magma degassing cannot explain the time variation of sulphur and HCl concentrations in the deep endmember, which are more probably linked to reactions of solid phases at depth, before mixing with the hydrothermal vapours. Based on the P^T conditions and speciation of the boiling hydrothermal system below La Fossa, the HCl and Stot contents in the hydrothermal vapours were used to compute the redox conditions and pH of the aqueous solution. The results suggest that the haematite magnetite buffer controls the hydrothermal fO2 values, while the pH has increased since the end of the 1970s. The main processes affecting pH values may be linked to Na^Ca exchanges between evolved seawater, feeding the boiling hydrothermal system, and local rocks. While Na is removed from water, calcium enters the solution, undergoes hydrolysis and produces HCl,lowering the pH of the water. The increasing water^rock ratio within the hydrothermal system lowers the Ca availability, so the aqueous solution becomes less acidic. Seawater flowing towards the boiling hydrothermal brine dissolves a large quantity of pyrite along its path. In the boiling hydrothermal system, dissolved sulphur precipitates as pyrite and anhydrite, and becomes partitioned in vapour phase as H2S and SO2. These results are in agreement with the paragenesis of hydrothermal alteration minerals recovered in drilled wells at Vulcano and are also in agreement with the isotopic composition of sulphur emitted by the crater fumaroles.
    Description: Published
    Description: 137-150
    Description: partially_open
    Keywords: chlorine ; sulphur ; hydrothermal system ; genetic processes ; Vulcano Island ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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    Groundwater radon measurements in the Mt. Etna area (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Radon levels were measured in 119 groundwater samples collected throughout the active volcanic area of Mt. Etna by means of a portable Lucas-type scintillation chamber. The measured activity values range from 1.8 to 52.7 Bq l 1. About 40% of the samples exceed the maximum contaminant level of 11 Bq l 1 proposed by the USEPA in 1991. The highest radon levels are measured in the eastern sector of the volcano, which is the seismically most active zone of the volcano. On the contrary the south-western sector, which is both seismically active and a site of intense magmatic degassing, display lower radon levels. This is probably due to the formation of a free gas phase (oversaturation of CO2) that strips the radon from the water. Comparison of the data gathered at Mt. Etna with those of other areas indicates that 222Rn activity in groundwater is positively correlated with both the content of parent elements in the aquifer rocks and the temperature of the geothermal systems that interacts with the sampled aquifers.
    Description: Published
    Description: 187–201
    Description: partially_open
    Keywords: Groundwater ; Radon ; Mount Etna ; Active volcanic areas ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.02. Hydrology::03.02.06. Water resources ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.07. Radioactivity and isotopes ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.08. Risk::05.08.01. Environmental risk
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  • 27
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    Contrasting triggering mechanisms of the 2001 and 2002–2003 eruptions of Mount Etna (Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Mount Etna produced two significant eruptions in 2001 and 2002–2003, which we have analysed using geological, seismic and deformation data. These eruptions showed some similarities, such as the activating of two magmatic plumbing systems (central–lateral and eccentric), but they differed in their triggering mechanisms. While the 2001 eruption was largely the result of the emplacement of a N–S eccentric dike (independent from the central conduits) consistent with E–W regional extension, the 2002–2003 eruption occurred in response to a major flank slip on the eastern and southeastern sides of the volcano. This is demonstrated by the spatial and temporal distribution of seismicity and deformation preceding and accompanying the two eruptions. During the months prior to the 2001 eruption, most epicenters were concentrated on the southern flank, at depths of 5–15 km below sea level. During the 4 days before the eruption, earthquake hypocenters migrated to shallower levels (from 5 km bsl. upward) indicating the emplacement of the eccentric dike. This is confirmed by the patterns of ground fracturing observed in the field and deformation documented by electronic distance measurements (EDM). In contrast, the months before the 2002–2003 eruption were characterised by shallower seismicity, mainly concentrated along the active faults bordering the slipping flank sector. Flank slip accelerated in September 2002 and a second, more vigorous acceleration of flank slip occurred on 26–27 October 2002, accompanying the opening of eruptive vents. The very short (2 h) seismic crisis preceding the onset of eruptive activity stands in neat contrast with the 4 days of intense seismicity before the 2001 eruption. Subsequently, flank slip-deformation extended all over the eastern and southeastern flanks of the volcano, causing serious damage in this sector. The events of 2001–2003 can be seen as a continuous chain of intimately interacting processes including regional tectonics, magma accumulation and eruption, and flank instability. In this scenario the 2001 eruption led to increased flank instability that subsequently accelerated and culminated with the massive flank slip, which in turn facilitated the 2002–2003 eruption. This sequence of events points to a long-term feedback mechanism between magmatism and flank instability at Etna.
    Description: Published
    Description: 235-255
    Description: partially_open
    Keywords: eruption triggering ; central–lateral vs. eccentric eruptions ; flank instability and slip ; volcano-tectonics ; Mt. Etna ; instrumental monitoring ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 28
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    A multidisciplinary approach to detect active pathways for magma migration and eruption at Mt. Etna (Sicily, Italy) before the 2001 and 2002-03 eruptions (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Two strong flank eruptions occurred in July–August 2001 and from late October 2002 to late January 2003 at Mt. Etna volcano. The two eruptions mainly involved the upper southern flank of the volcano, a particularly active area during the last 30 years, damaging several tourist facilities and threatening some villages. The composite eruptive activity on the upper southern flank of Mt. Etna during 2001–2003 has confirmed “a posteriori” the results of a multidisciplinary study, started well before its occurrence by combining geological, seismic and geochemical data gathered in this part of the volcano. We were able, in fact, to highlight fractured zones likely to be re-activated in the near future in this area, where the largest majority of eruptive fissures in the recent past opened along N120° to N180° ranging directions. The spatial distribution of earthquake epicentres during the period June 30th 2000–June 30th 2001 showed the greatest frequency in a sector compatible with both the direction of the main fissures of the pre-2001 period and that of the 2001 and 2002 lateral eruptions. Soil CO2 and soil temperature surveys carried out in the studied area during the last 3 years have revealed anomalous release of magmatic fluids (mainly CO2 and water vapour) along some NNW–SSE-trending volcano-tectonic structures of the area even during inter-eruptive periods, indicating persistent convective hydrothermal systems at shallow depth connected with the main feeder conduits of Etna. The temporal changes in both seismic and geochemical data from June 30th, 2000 to June 30th, 2001 were compared with the evolution of volcanic activity. The comparison allowed to recognize at least two sequences of anomalous signals (August to December 2000 and April to June 2001), likely related to episodes of step-like magma ascent towards the surface, as indicated by the following eruptive episodes. The N120° to N180° structural directions are in accord with one of the main structural lines affecting eastern Sicily; they would be important pathways for magma uprise to the surface that will keep on feeding the eruptive activity of Etna in the near future. This study also pointed out the high instability of the southern slope of Etna, a sector where the potential hazard by lava flow invasion will remain high also in the near future.
    Description: Published
    Description: 20
    Description: partially_open
    Keywords: Mt. Etna ; fault detection ; soil gas ; historical eruptive fissures ; eruptive activity ; local seismicity ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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    Fluid circulation and structural discontinuities inside Misti volcano (Peru) inferred from self-potential measurements (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: One of the seven potentially active andesite stratovolcanoes in southern Peru, Misti (5822 m), located 17 km northeast and 3.5 km above Arequipa, represents a major threat to the population (f900,000 inhabitants). Our recent geophysical and geochemical research comprises an extensive self-potential (SP) data set, an audioâ magnetotelluric (AMT) profile across the volcano and CO2 concentrations in the soil along a radial profile. The SP survey is the first of its kind in providing a complete mapping of a large andesitic stratovolcano 20 km in diameter. The SP mapping enables us to analyze the SP signature associated with a subduction-related active volcano. The general SP pattern of Misti is similar to that of most volcanoes with a hydrogeologic zone in the lower flanks and a hydrothermal zone in the upper central area. A quasi-systematic relationship exists between SP and elevation. Zones with constant SP/altitude gradients (Ce) are observed in both hydrogeologic (negative Ce) and hydrothermal (positive Ce) zones. Transition zones between the different Ce zones, which form a concentric pattern around the summit, have been interpreted in terms of lateral heterogeneities in the lithology. The highest amplitudes of SP anomalies seem to coincide with highly resistive zones. The hydrothermal system 6 km in diameter, which extends over an area much larger than the summit caldera, may be constrained by an older, concealed collapse caldera. A sealed zone has apparently developed through alteration in the hydrothermal system, blocking the migration of CO2 upward. Significant CO2 emanations are thus observed on the lower flanks but are absent above the hydrothermal zone.
    Description: - Institut de Recherche pour le Developpement (IRD) - Instituto Geofısico del Peru´ (IGP)
    Description: Published
    Description: 343-360
    Description: partially_open
    Keywords: Misti volcano ; self-potential ; audioâ magnetotelluric ; electrical resistivity ; structural discontinuity ; hydrothermal system ; Peru ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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    Probabilistic source location of explosion quakes at Stromboli volcano estimated with double array data (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Data from two dense arrays of short-period seismometers are used to retrieve source locations of the explosion quakes at Stromboli volcano. Slowness vectors stimated at both arrays with the zero-lag cross-correlation technique constitute the experimental data set. A probabilistic approach based on a grid search spanning the volcano interior is used to calculate the probability of the source location. Results depict a shallow source, located beneath the crater area, at depths not greater than 500 m below the surface. Results are slightly different from, but comparable to, those obtained in a companion experiment carried out in the same time period using a broad-band seismometer network, which show a source shifted some hundreds of meters northwest of the crater area. The method is revealed to be effective and useful for future studies having the purpose of real-time tracking of the explosion quakes and tremor.
    Description: Published
    Description: 123-142
    Description: partially_open
    Keywords: Stromboli ; Array ; Explosion quake ; Source location ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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    Trace metal modeling of groundwater–gas–rock interactions in a volcanic aquifer: Mount Vesuvius, Southern Italy (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We report a detailed study of trace metals in groundwaters from the Somma-Vesuvius volcanic complex and present a model of the chemical processes that control the fate of these components during gas–water–rock interactions. Trace metal concentrations in Vesuvian groundwaters range from 0.01 to 0.1 Ag/l for ultra-trace elements (Sb, Cs, Co, Cd, and Pb) up to 0.1–10 mg/l for minor elements (Fe and Sr), leading to water–rock ratios from ~0.5 to 10 9 when normalized to trace element concentrations in the host rocks. Our results indicate non-isochemical dissolution of local volcanic rocks by groundwaters,during which mobile trace elements (As, Se, Mo, V, Li) are enriched and elements such as Al, Pb, Co, and Mn are depleted in the aqueous phase compared to the pristine composition of unleached rocks. Speciation computation and mineral–solution equilibria provide insights into the processes controlling the abundance and mobility of both major and trace elements in the fluids and allow quantitative modeling of gas–water–rock interactions. This latter was done using a forward reaction path model based on the principle of irreversible reactions involving minerals and aqueous solutions (Helgeson, H.C., 1968. Evaluation of irreversible reactions in geochemical processes involving minerals and aqueous solutions: I. Thermodynamic relations. Geochim. Cosmochim. Acta, 32, 853–877), and incorporating transition-state theory to account for rates of mineral dissolution reactions (Aagaard, P., Helgeson, H.C., 1982. Thermodynamic and kinetic constraints on reaction rates among minerals and aqueous solutions, 1. Theoretical considerations. Amer. J. Sci., 282, 237–285). The EQ3NR/6 software package (Wolery, T.J.,1994. EQ3NR, Letter report: EQ3/6 version 8.0. Differences from version 7. UCRL_ID_129749, Lawrence Livermore National Laboratory, Livermore, California) was used to simulate the reaction paths and the aqueous concentrations of trace elements with increasing extent of rock weathering. Fairly good matching between the modeled and analytical groundwater compositions supports the validity of our approach and provides reliable information on the main sources and sinks of trace metals during gas–water–rock interactions in the volcanic aquifer of Vesuvius.
    Description: Published
    Description: 289– 311
    Description: partially_open
    Keywords: trace elements ; Vesuvius ; EQ3/6 ; kinetics ; weathering ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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  • 32
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    Scaling characteristics of local geomagnetic field and seismicity at Etna volcano and their dynamics in relation to the eruptive activity (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The evolution of scaling characteristics of the local geomagnetic field and of the seismicity at Etna volcano is studied in relation to the strong eruptive activity occurred here from 2000 to 2002. Scaling laws are found in the hourly time variability of magnetic data and in the seismicity pattern. The scaling exponents suggest the presence of persistent temporal fluctuations. Clear links between the dynamics of the measured data and the eruptive volcanic episodes are revealed. Fractal dimensions of seismicity seem to be always correlated to the beginning of main eruptive events, while strong alterations of the dynamics of the local magnetic field take place only when the eruptive fractures opened very close to the magnetic sites.
    Description: Published
    Description: 96-106
    Description: partially_open
    Keywords: scaling characteristics ; volcanic eruptions ; geomagnetic field ; seismic activity ; Mt. Etna ; 04. Solid Earth::04.05. Geomagnetism::04.05.02. Geomagnetic field variations and reversals ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 33
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    Nested zones of instability in the Mount Etna volcanic edifice, Italy (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Large-scale flank instability on Mount Etna is associated with a distinct set of faults radiating generally from the summit area and restricted to the volcanic edifice itself. New observations and mapping of very recent and continuing deformation along these faults and related structures have been analysed in combination with published information, including recent seismic and eruption data, enabling the faults to be placed in three groups. Two of these, the Pernicana fault system (PFS) and the Ragalna fault system (RFS) bound, respectively, the northern and south-western margins of instability. Their activity responds to cycles of magma pressure associated with flank eruptions, together with subsequent deflation as gravity dominates. These cycles may operate at different depths, with the RFS bordering deep-seated instability. Their positions appear governed by the contact, in the substrate of the volcano, between relatively weak early Quaternary clays and stronger rocks of the Apennine–Maghrebian Chain that rise towards the north and west in the subsurface, buttressing the edifice in these directions. The unstable mass to the un-buttressed south and east is thus defined by its weak substrate and displays structures similar to those produced in model experiments. The third fault group, the Mascaluci–-Trecastagni fault system, borders a rather faster-moving zone of instability in the eastern part of the large unstable mass, outlining one element in a nested pattern in map view. Low-angle detachments below the unstable zones are thought to occur at different levels above a deep and laterally extensive detachment associated with the RFS, producing a nested pattern in section as well. This is illustrated by the PFS where the long-recognised western half of the fault borders a fast moving zone of instability riding above a detachment that daylights as a thrusted deformation front marked by recurring landsliding at an approximate mid-slope position on the volcano. Downslope, the newly recognised eastern extension of the PFS, exhibiting slip-rates an-order-of-magnitude lower than the western segment, is thought to border a deeper slow-moving detachment that daylights offshore. Windows of deformed sub-Etnean clays at anomalously high altitudes may indicate where similar detachments, no longer mechanically favoured and now inactive, have daylighted. As a result, the edifice can be considered, overall, as consisting of multiple unstable areas, nested in plan view and with basal detachments occurring at different levels in section. This model of edifice behaviour is regarded as an evolving one, with detachments waxing and waning in their activity as flank movement progresses.
    Description: Published
    Description: 137-153
    Description: partially_open
    Keywords: Mount Etna ; instability; flank faults ; volcano collapse models ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 34
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    Magma dynamics in the shallow plumbing system of Mt. Etna as recorded by compositional variations in volcanics of recent summit activity (1995–1999) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We describe the reactivation and the successive evolution of the shallow plumbing system of Mt. Etna between the end of the largest flank eruption of the last three centuries (1991–1993) and the subterminal eruption from South-East Crater (SEC), which occurred between February and mid-November 1999. Our analysis is based on observations of the volcanic activity and petrological studies of the erupted volcanics. Bulk rock, mineral and glass compositions have been determined for more than 80 samples erupted from the four summit craters between October 1995 and February 1999. These data allow us to recognise significant compositional variations among the products of different craters. In particular, volcanics produced between 1995 and 1999 by Bocca Nuova (BN), Voragine (VOR) and North-East Crater (NEC) show limited compositional variations and are similar to those observed during recent eruptions (e.g., 1991–93). More primitive magmas have been produced during the more vigorous fire fountains episodes. On the contrary, the South-East Crater produced slightly more differentiated volcanics than those of the other summit craters following its reactivation (November 1996) until the end of 1998. Whole rock compositions of products from this crater show low CaO/Al2O3, whereas interstitial glasses have lower MgO and higher alkali contents than those from the other craters. However, since the beginning of 1999, and just before the start of the subterminal eruption from SEC, the volcanics erupted from this crater progressively changed in composition, becoming similar to those of the other craters. This trend indicates that within the conduits of the summit craters, distinct thermal and fluid-dynamical regimes can evolve, controlling the cooling and crystallisation of Etna magmas.
    Description: Published
    Description: 55-71
    Description: partially_open
    Keywords: Mount Etna ; crystal fractionation ; petrologic monitoring and magmatic process ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
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  • 35
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    Genesis of fumarolic emissions as inferred by isotope mass balances: CO2 and water at Vulcano Island, Italy (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We have developed a quantitative model of CO2 and H2O isotopic mixing between magmatic and hydrothermal gases for the fumarolic emissions of the La Fossa crater (Vulcano Island, Italy). On the basis of isotope balance equations, the model takes into account the isotope equilibrium between H2O and CO2 and extends the recent model of chemical and energy two-end-member mixing by Nuccio et al. (1999). As a result,the H2O and CO2 content and the dD, d18O, and d13C isotope compositions for both magmatic and hydrothermal end-members have been assessed. Low contributions of meteoric steam, added at a shallow depth, have been also recognized and quantified in the fumaroles throughout the period from 1988 to 1998. Nonequilibrium oxygen isotope exchange also seems to be occurring between ascending gases and wall rocks along some fumarolic conduits. The d13CCO2 of the magmatic gases varies around -3 to 1‰ vs. Peedee belemnite (PDB), following a perfect synchronism with the variations of the CO2 concentration in the magmatic gases. This suggests a process of isotope fractionation because of vapor exsolution caused by magma depressurization. The hydrogen isotopes in the magmatic gases (-1 to -35‰ vs. standard mean ocean water [SMOW]), as well as the above d13CCO2 value, are coherent with a convergent tectonic setting of magma generation, where the local mantle is widely contaminated by fluids released from the subducted slab. Magma contamination in the crust probably amplifies this effect. The computed isotope composition of carbon and hydrogen in the hydrothermal vapors has been used to calculate the dD and d13C of the entire hydrothermal system, including mixed H2O-CO2 vapor, liquid water, and dissolved carbon. We have computed values of about 10‰ vs. SMOW for water and -2 to -6.5‰ vs. PDB for CO2. On these grounds, we think that Mediterranean marine water (dDH2O 10‰) feeds the hydrothermal system. It infiltrates at depth throughout the local rocks, reaching oxygen isotope equilibrium at high temperatures. Interaction processes between magmatic gases and the evolving seawater also seem to occur, causing the dissolution of isotopically fractionated aqueous CO2 and providing the source for hydrothermal carbon. These results have important implications concerning fluid circulation beneath Vulcano and address the more convenient routine of geochemical surveillance.
    Description: Published
    Description: 759–772
    Description: partially_open
    Keywords: isotope geochemistry ; volcanic gases ; mixing modeling ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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  • 36
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    Influence of volcanic activity on spring water chemistry at Popocatepetl Volcano, Mexico (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The results of the 7 years (1994-2000) of monthly monitoring of spring water before and during eruptions show response to volcanic activity. Low salinity and temperature characterize most of the springs, which are located on the flanks of Popocatepetl Volcano. The pH ranges from 5.8 to 7.8 and temperature from 3 to 36 jC. Oxygen and hydrogen isotopic data show that the water is of meteoric origin, but SO4 2 , Cl , F , HCO3 , B, and SO4 2- /Cl- variations precede main eruptive activity, which is considered linked to influx of magmatic gases and acid fluids that react with sublimates and host rock and mix with the large water system. Na +, Ca2 + , SiO2 and Mg2 + concentrations in the water also increased before eruptive activity. The computed partial pressure of CO2 in equilibrium with spring waters shows values higher than air-saturated water (ASW), with the highest values up to 0.73 bar of pCO2. Boron is detected in the water only preceding the larger eruptions. When present, boron concentration is normally under health standard limits, but in two cases the concentration was slightly above. Other components are within health standard limits, except for F- in one spring.
    Description: Published
    Description: 207– 229
    Description: partially_open
    Keywords: Volcano monitoring ; Spring water chemistry ; Popocatepetl ; Mexico ; 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
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  • 37
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    Comment on ‘Conduit convection, magma mixing, and melt inclusion trends at persistent degassing volcanoes’ by Fred Witham, published in Earth Planetary Science Letters (2011) 301, 345–352 (2012)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: No abstract
    Description: Published
    Description: 306-308
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: JCR Journal
    Description: reserved
    Keywords: Etna ; Stromboli ; volatiles ; melt inclusions ; magma mixing ; magma degassing ; 04. Solid Earth::04.04. Geology::04.04.07. Rock geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 38
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    An emergent strategy for volcano hazard assessment: From thermal satellite monitoring to lava flow modeling (2012)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Spaceborne remote sensing techniques and numerical simulations have been combined in a web-GIS framework (LAV@HAZARD) to evaluate lava flow hazard in real time. By using the HOTSAT satellite thermal monitoring system to estimate time-varying TADR (time averaged discharge rate) and the MAGFLOW physicsbased model to simulate lava flow paths, the LAV@HAZARD platform allows timely definition of parameters and maps essential for hazard assessment, including the propagation time of lava flows and the maximum run-out distance. We used LAV@HAZARD during the 2008–2009 lava flow-forming eruption at Mt Etna (Sicily, Italy). We measured the temporal variation in thermal emission (up to four times per hour) during the entire duration of the eruption using SEVIRI and MODIS data. The time-series of radiative power allowed us to identify six diverse thermal phases each related to different dynamic volcanic processes and associated with different TADRs and lava flow emplacement conditions. Satellite-derived estimates of lava discharge rates were computed and integrated for the whole period of the eruption (almost 14 months), showing that a lava volume of between 32 and 61 million cubic meters was erupted of which about 2/3 was emplaced during the first 4 months. These time-varying discharge rates were then used to drive MAGFLOW simulations to chart the spread of lava as a function of time. TADRs were sufficiently low (b30 m3/s) that no lava flows were capable of flowing any great distance so that they did not pose a hazard to vulnerable (agricultural and urban) areas on the flanks of Etna.
    Description: Published
    Description: 197-207
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Etna volcano Infrared remote sensing Numerical simulation GIS Lava hazard assessment ; 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::05.01. Computational geophysics::05.01.01. Data processing ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation ; 05. General::05.05. Mathematical geophysics::05.05.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 39
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    Coupled use of COSPEC and satellite measurements to define the volumetric balance during effusive eruptions at Mt. Etna, Italy (2012)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Using Etna as a case study location, we examine the balance between the volume of magma supplied to the shallow volcanic system (using ground-based SO2 data) and the volume erupted (using satellite thermal data). We do this for three eruptions of Mt. Etna (Italy) during 2002 to 2006. We find that, during the three eruptions, 2.3×107 m3 or 24% of the degassed volume remained unerupted. However, variations in the degree of partitioning between supplied (Vsupply) and erupted (Verupt) magma occur within individual eruptions over the time scales of days. Consequently, we define and quantify three types of partitioning. In the first case, VsupplybVerupt, i.e. more lava is erupted than is supplied. In such a case previously degassed magma is erupted or magma can rise faster than it is able to degas, as occurred during the open phases of the 2002–2003 and 2004–2005 eruptions, respectively. In the second case, VsupplyNVerupt, i.e. less lava is erupted than is supplied. In such a case, magma can erupt in an explosive manner, as occurred during Phase II of the 2002–2003 eruption, or remain within or below the edifice. In the third case, Vsupply=Verupt, i.e. all supplied magma is erupted. During 2002–2006, over a total of 280 days of eruptive activity, this balancing case applied to 50% of the time.
    Description: Published
    Description: 47-53
    Description: JCR Journal
    Description: reserved
    Keywords: Etna ; thermal remote sensing ; SO2 flux ; Effusive eruption ; mass balance ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 40
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    Mapping and DOWNFLOW simulation of recent lava flow fields at Mount Etna (2012)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: In recent years, progress in geographic information systems (GIS) and remote sensing techniques have allowed the mapping and studying of lava flows in unprecedented detail. A composite GIS technique is introduced to obtain high resolution boundaries of lava flow fields. This technique is mainly based on the processing of LIDAR-derived maps and digital elevation models (DEMs). The probabilistic code DOWNFLOW is then used to simulate eight large flow fields formed at Mount Etna in the last 25 years. Thanks to the collection of 6 DEMs representing Mount Etna at different times from 1986 to 2007, simulated outputs are obtained by running the DOWNFLOW code over pre-emplacement topographies. Simulation outputs are compared with the boundaries of the actual flow fields obtained here or derived from the existing literature. Although the selected fields formed in accordance with different emplacement mechanisms, flowed on different zones of the volcano over different topographies and were fed by different lava supplies of different durations, DOWNFLOW yields results close to the actual flow fields in all the cases considered. This outcome is noteworthy because DOWNFLOW has been applied by adopting a default calibration, without any specific tuning for the new cases considered here. This extensive testing proves that, if the pre-emplacement topography is available, DOWNFLOW yields a realistic simulation of a future lava flow based solely on a knowledge of the vent position. In comparison with deterministic codes, which require accurate knowledge of a large number of input parameters, DOWNFLOW turns out to be simple, fast and undemanding, proving to be ideal for systematic hazard and risk analyses.
    Description: Published
    Description: 27-39
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: 5.5. TTC - Sistema Informativo Territoriale
    Description: JCR Journal
    Description: reserved
    Keywords: LIDAR ; lava flow field ; lava flow simulation ; Digital elevation model ; Mount Etna ; 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 41
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    Texture analysis of volcanic rock samples: Quantitative study of crystals and vesicles shape preferred orientation from X-ray microtomography data (2012)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: In the texture analysis of volcanic rocks, the preferred orientation of the constituents can provide useful information for the interpretation of the processes involved in the rock formation. We present here a new data analysis technique, based on X-ray microtomography measurements and on shape preferred orientation analysis, to obtain the orientation distribution functions of the constituents of volcanic rocks. This procedure proved to be very suitable for volcanic samples, where diffraction-based techniques, developed for crystallographic preferred orientation studies, are of limited utilization, in addition to the fact that they cannot provide any information about vesicles or bubbles. Moreover the analysis performed directly in three dimensions (3D) overcomes the problems that usually occur when employing stereological methods for the analysis of the images obtained via microscopy-based techniques. In this study, two scoriae (from Stromboli and Etna) and a tube pumice (from Campi Flegrei) were measured via X-ray microtomography and then the resulting volumes were analyzed following the proposed procedure. Results highlight little preferred orientation for the vesicles in the two scoria samples, whereas the pumice shows a marked preferred orientation. Crystals (also divided by mineral species) were taken into account as well and in the two scoria samples there is no crystal preferred orientation, in contrast with the pumice, where crystal preferred orientation features are very similar to the ones found for the vesicles. Overall we found strong differences in preferred orientation: weak for vesicles in scoriae, showing an axial symmetry with the axis parallel to the elongation axis of the sample, and a stronger and more complex orientation texture in the pumice sample for both crystals and vesicles. The promising results obtained suggest that this procedure is potentially very useful for the analysis of preferred orientation in volcanic rocks and geomaterials in general.
    Description: Published
    Description: 83-95
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: X-ray computed microtomography ; preferred orientation ; texture analysis ; volcanic scoria ; synchrotron X-rays ; pumice ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 42
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    Pattern recognition of volcanic tremor data on Mt. Etna (Italy) with KKAnalysis — A software program for unsupervised classification (2012)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Continuous seismic monitoring plays a key role in the surveillance of the Mt. Etna volcano. Besides earthquakes, which often herald eruptive episodes, the persistent background signal, known as volcanic tremor, provides important information on the volcano status. Changes in the regimes of activity are usually concurrent with variations in tremor characteristics. As continuous recording leads rapidly to the accumulation of large amounts of data, parameter extraction and automated processing become crucial. We propose techniques of unsupervised classification and present a software, named KKAnalysis, developed for this purpose. Essentials of KKAnalysis are demonstrated on tremor data recorded on Mt. Etna during various states of volcanic activity encountered in 2007 and 2008. KKAnalysis is based on MATLAB and combines various unsupervised pattern recognition techniques, in particular self-organizing maps (SOM) and cluster analysis. An early software version was successfully applied to seismic signals recorded on Mt. Etna during the eruption in 2001. Since each situation may require different configurations, we designed KKAnalysis with a specific GUI allowing users to easily modify parameters. All results are given graphically, in screen plots and metafiles (MATLAB and TIF format), as well as in alphanumeric form. The synoptic visualization of results from SOM and cluster analysis facilitates an immediate inspection. The potential of this representation is demonstrated by focusing on data recorded during a flank eruption on May 13, 2008. Changes of tremor characteristics can be clearly identified at a very early stage, well before enhanced volcanic activity becomes visible in the time series. At the same time, data reduction to less than 1% of the original amount is achieved, which facilitates interpretation and storage of the essential information. Running the program in a typical configuration requires computing time less than 1 min, allowing an on-line application for early warning purposes at INGV–Sezione di Catania
    Description: Published
    Description: 953-961
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 5.6. TTC - Attività di Sala Operativa
    Description: JCR Journal
    Description: reserved
    Keywords: Self-Organizing Map ; Cluster Analysis ; K-means ; Fuzzy C-means ; Volcano Seismology ; Volcano Monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.01. Computational geophysics::05.01.01. Data processing ; 05. General::05.01. Computational geophysics::05.01.02. Cellular automata, fuzzy logic, genetic alghoritms, neural networks ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 43
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    Aggregation-dominated ash settling from the Eyjafjallajökull volcanic cloud illuminated by field and laboratory high-speed imaging (2012)
    Geologica Society of America
    Details
    Publication Date: 2022-05-04
    Description: The recent Eyjafjallajökull (Iceland) eruption strikingly under-lined the vulnerability of a globalized society to the atmospheric dispersal of volcanic clouds from even moderate-size eruptions. Ash aggregation controls volcanic clouds dispersal by prematurely remov-ing fi ne particles from the cloud and depositing them more proxi-mally. Physical parameters of ash aggregates have been modeled and derived from ash fallout deposits of past eruptions, yet aggregate sedimentation has eluded direct measurement, limiting our ability to predict the dispersal of volcanic clouds. Here we use fi eld-based, high-speed video analysis together with laboratory experiments to provide the fi rst in situ investigation and parameterization of the physical fea-tures and settling dynamics of ash aggregates from a volcanic cloud. In May 2010, high-speed video footage was obtained of both ash par-ticles and aggregates settling from the Eyjafjallajökull volcano erup-tion cloud at a distance of 7 km from the vent; fallout samples were collected simultaneously. Experimental laboratory determinations of the density, morphology, and settling velocity of individual ash par-ticles enable their distinction from aggregates. The combination of fi eld and experimental analyses allows a full characterization of the size, settling velocity, drag coeffi cient, and density distributions of ash aggregates as well as the size distribution of their component par-ticles. We conclude that ash aggregation resulted in a tenfold increase in mass sedimentation rate from the cloud, aggravating the ash haz-ard locally and modifying cloud dispersal regionally. This study pro-vides a valuable tool for monitoring explosive eruptions, capable of providing robust input parameters for models of cloud dispersal and consequent hazard forecast
    Description: Published
    Description: 891–894
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: aggregation ; ash ; 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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  • 44
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    Rock magnetism and compositional investigation of Brown Tuffs deposits at Lipari and Vulcano (Aeolian Islands — Italy) (2012)
    Elsevier
    Details
    Publication Date: 2021-12-06
    Description: A rock-magnetic investigation was carried out on the nonwelded ash deposits of the Brown Tuffs (Aeolian Islands, southern Tyrrhenian Sea) to improve the stratigraphic correlation between the deposits cropping out on Lipari and Vulcano islands and locate their source area. The study was supplemented by petrographical and geochemical analyses on selected strata, with the intent to compare the Brown Tuffs to other rocks emplaced at Vulcano in the same time span. More than 30 levels were sampled in the intermediate (56± 4 kaNIBTN21–22 ka) and upper (21–22 kaNUBT) parts of the Brown Tuffs sequences on the two islands. Their characteristic remanent magnetization (ChRM) directions were derived from stepwise thermal demagnetization, and the magnetic fabric from measurements of the anisotropy of magnetic susceptibility. The levels with indistinguishable ChRM directions were regarded as coeval and to form an individual stratigraphic unit. The units were referred to the Brown Tuffs sequence of Lucchi et al. (2008) on the grounds of their emplacement age, provided by comparison of their mean paleomagnetic direction with the paleosecular variation curves of the southern Tyrrhenian region, as well as the field constraints. The closer correlation between the sequences of Lipari and Vulcano contributes to a better understanding of the volcanic activity that produced the Brown Tuffs, and shows that most of the IBT and the oldest UBT levels were emplaced in a short time span, between ≈24 and 20–17 ka. The magnetic fabric is typically well developed, but at most sites the magnetic foliation is very close to horizontal and no imbrication is defined. The source area of the Brown Tuffs parent pyroclastic flows, as constrained from the intersection of the magnetic lineations, falls in the northeastern part of La Fossa Caldera structure. Although limited to major elements, compositional data provide further indication about the parent plumbing system and its behaviour. Magma batch(es) involved in the IBT eruptions have homogeneous features and underwent frequent refilling and tapping processes. Conversely, those involved in the early UBT eruptions are compositionally more variable. This suggests more complex evolution and plumbing system activity: the UBT eruptions represent either residual mafic magmas from the previous eruptions or the arrival of new, fresh shoshonitic magma in the system.
    Description: Published
    Description: 23-38
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: JCR Journal
    Description: reserved
    Keywords: Brown Tuffs ; Magnetic fabric ; pyroclastic rocks ; Aeolian Islands ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 45
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    Dynamic plumbing system beneath volcanoes revealed by kinetic modeling, and the connection to monitoring data: An example from Mt. Etna (2012)
    Elsevier
    Details
    Publication Date: 2023-01-27
    Description: Our ability to monitor volcanoes (using seismic signals, ground deformation, gas fluxes, or other ground and satellite based observations) as well as our understanding of melt reservoirs that feed eruptions have evolved tremendously in recent years. The complex plumbing systems that are thought to feed eruptions are, however, difficult to relate to the monitoring signals. Here we show that the record preserved in compositional zoning of erupted minerals may be used to reconstruct sections of the plumbing system. Kinetic modeling of such zoning can yield information on the residence time of magma in different segments of the plumbing systems. This allows a more nuanced evaluation of the link between observed monitoring signals or eruption styles and the magmatic processes and movement of batches of melts at depth. The approach is illustrated through a study of the compositional zoning recorded in olivine crystals from the 1991–1993 SE-flank eruption products of Mt. Etna (Sicily). The zoning patterns in crystals reveal that the plumbing system of the volcano consisted of at least three different magmatic environments between which magma was transported and mixed in the year or two preceding the start of eruption. Quantification of this history indicates that two main pathways of melt migration and three timescales dominated the dynamics of the system. Combination of this information with the timing of observation of various monitoring signals allows a reconstruction of the dynamic evolution of this section of the plumbing system during the early stages of the 1991–1993 eruption. It is seen, for example, how the migration of melt through the same sections of the plumbing system can cause pre-eruptive triggering, enhance Strombolian activity, and through the ensuing eruption cleanse and flush the plumbing system. Different kinds of mixing occur simultaneously at different sections of the plumbing system on different timescales (a few days up to two years).
    Description: Published
    Description: 11-22
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: JCR Journal
    Description: reserved
    Keywords: Etna ; plumbing system ; olivine ; zoning ; timescales ; monitoring ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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