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  • 04. Solid Earth::04.08. Volcanology::04.08.01. Gases  (7)
  • 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas  (7)
  • 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology  (6)
  • Acoustics
  • Applied geophysics
  • Data analysis / ~ processing
  • Fluids
  • Schussler
  • Textbook of geophysics
  • Elsevier  (20)
  • Elsevier B.V.  (3)
  • Cambridge Univ. Press
  • Istituto Nazionale di Geofisica e Vulcanologia
  • W.H. Freeman
  • 2010-2014  (23)
  • 2000-2004
  • 1980-1984
  • 2010  (23)
Collection
Keywords
Publisher
Years
  • 2010-2014  (23)
  • 2000-2004
  • 1980-1984
Year
  • 1
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    Carbonate assimilation in magmas: a reappraisal based on experimental petrology (2010)
    Elsevier
    Details
    Publication Date: 2020-11-13
    Description: The main effect of magma-carbonate interaction on magma differentiation is the formation of a silica-undersaturated, alkali-rich residual melt. Such a desilication process was explained as the progressive dissolution of CaCO3 in melt by consumption of SiO2 and MgO to form diopside sensu stricto. Magma chambers emplaced in carbonate substrata, however, are generally associated with magmatic skarns containing clinopyroxene with a high Ca-Tschermak activity in their paragenesis. Data are presented from magma-carbonate interaction experiments, demonstrating that carbonate assimilation is a complex process involving more components than so far assumed. Experimental results show that, during carbonate assimilation, a diopside-hedenbergite-Ca-Tschermak clinopyroxene solid solution is formed and that Ca-Tschermak/diopside and hedenbergite/diopside ratios increase as a function of the progressive carbonate assimilation. Accordingly, carbonate assimilation reaction should be written as follows, taking into account all the involved magmatic components: CaCO3solid+SiO2melt+MgOmelt+FeOmelt+Al2O3melt → (Di-Hd-CaTs)sssolid+CO2fluid The texture of experimental products demonstrates that carbonate assimilation produces three-phases (solid, melt, and fluid) whose main products are: i) diopside-hedenbergite-Ca-Tschermak clinopyroxene solid solution; ii) silica-undersaturated CaO-rich melt; and iii) C-O-H fluid phase. The silica undersaturation of the melt and, more importantly, the occurrence of a CO2-rich fluid phase, must be taken into account as they significantly affect partition coefficients and the redox state of carbonated systems, respectively.
    Description: TRIGS Project “Sixth Framework Programme of the European Commission and to the New and Emerging Science and Technology Pathfinder". Project FIRB MIUR “Development of innovative technologies for the environmental protection from natural events”.
    Description: Published
    Description: 503-514
    Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Description: JCR Journal
    Description: open
    Keywords: carbonate assimilation ; skarns ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Seasonal cycles of seismic velocity variations detected using coda wave interferometry at Fogo volcano, São Miguel, Azores, during 2003–2004 (2010)
    Elsevier
    Details
    Publication Date: 2020-11-12
    Description: Fogo volcano is an active central volcano, with a lake filled caldera, in the central part of São Miguel Island, Azores, whose current activity is limited to hydrothermal manifestations such as active fumarolic fields, thermal and CO2 cold springs and soil diffuse degassing areas. It is affected by important active tectonic structures, with high seismic activity and practically continuous micro-seismicity. A recurrent feature from the seismicity observed in volcanic regions is the occurrence of clusters of similar earthquakes, whose origin can be attributed to the repeated action of a similar source mechanism at the same focal area. Doublets/multiplets were identified in this study within a catalogue of small magnitude (usually 〈 3) volcano tectonic events recorded in 2003–2004 by a selection of stations around Fogo volcano. All events have been cross-correlated and pairs whose waveforms exhibited a cross-correlation coefficient equal to or higher than 0.9 were analysed using the coda-wave interferometry technique. Subtle velocity variations found between events highlight a seasonal cycle of the velocity patterns, with lower velocity in winter time and higher velocity during summer months. Those results, together with quantitative differences between the same doublets at different stations, exhibit an excellent correlation with rainfall. A seasonal effect can also be broadly seen in the seismicity occurrence, and some of the swarms recorded over the two year period occur during the wettest season or close to episodes of abundant (above average) rainfall. Moreover, temporal and spatial analysis of several swarms highlighted the lack of any mainshock–aftershock sequence and organized migration of the hypocenters. This is suggestive of a very heterogeneous stress field. Vp/Vs is found to be lower than usually observed in volcanic areas, an occurrence likely related to the presence of steamy fluid associated with the geothermal system. Taken together, these observations suggest that pore pressurisation plays a major role in controlling a considerable part of the recorded seismicity. The geothermal fluids around Fogo massif have been identified as derived from meteoric water, which infiltrates through Fogo Lake and the volcano flanks and flows from south to north on the northern flank. All those elements seem to point to a role played by rainfall in triggering seismicity at São Miguel, possibly through pressure changes at depth in response to surface rain and/or an interaction with the geothermal system.
    Description: Published
    Description: 231-246
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: velocity changes ; rainfall ; volcano seismicity ; triggered seismicity ; Azores archipelago ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 3
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    Tornillos at Vulcano: Clues to the dynamics of the hydrothermal system (2010)
    Elsevier
    Details
    Publication Date: 2020-11-12
    Description: The number of tornillo events has recently increased at the Vulcano Island, Italy. While only 15 tornillos were recorded during 2004–2006, 584 events occurred in 2007–2008. They were located just below La Fossa Crater at depths ranging between 0.1 and 1 km b.s.l. During two intervals in 2007–2008 increases in the number of tornillos took place at the same time as temperature and geochemical anomalies were observed. The spectral content of the tornillos, generally characterized by one–two dominant spectral peaks near 6 and 10 Hz, varied over time, with changes also noted in the quality factors. The simplest source mechanism proposed for tornillos is the free eigenvibration of a fluid volume within a crack or a conduit. Based on this model, we propose a causal relationship between the temperature and geochemical anomalies and the increases in numbers of tornillos. As the amount of hydrothermal fluids increases during the anomalies, the upward flux of fluids grows. The consequent changes in the pressure, temperature and dynamics of the system of cracks and conduits result in the generation of tornillos. Based on the fluid-filled crack/conduit model, the shallow depths of the sources and the values of the quality factors, the fluid within the resonant crack/conduit was inferred to be an ash–gas or water droplet–gas mixture. Moreover, the observed variations in the wavefield can be caused by small changes in the location of the source, in the source mechanism, or in the medium in between the source and the seismic station. Finally, another peculiar feature of tornillos is the amplitude modulation that can be explained as a result of a beating phenomenon.
    Description: Published
    Description: 377-393
    Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Description: JCR Journal
    Description: reserved
    Keywords: Tornillos ; Vulcano Island ; Hydrothermal system ; Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
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    Mantle-derived carbon in Hercynian granites. Stable isotopes signatures and C/He associations in the thermomineral waters, N-Portugal (2010)
    Elsevier
    Details
    Publication Date: 2021-01-27
    Description: Na–HCO3–CO2-rich thermomineral waters issue in the N of Portugal, within the Galicia-Trás-os-Montes region, linked to a major NNE-trending fault, the so-called Penacova-Régua-Verin megalineament. Along this tectonic structure different occurrences of CO2-rich thermomineral waters are found: Chaves hot waters (67 °C) and also several cold (16.1 °C) CO2-rich waters. The δ2H and δ18O values of the thermomineral waters are similar to those of the local meteoric waters. The chemical composition of both hot and cold mineral waters suggests that water–rock reactions are mainly controlled by the amount of dissolved CO2 (g) rather than by the water temperature. Stable carbon isotope data indicate an external CO2 inorganic origin for the gas. δ13CCO2 values ranging between −7.2‰ and −5.1‰ are consistent with a two-component mixture between crustal and mantle-derived CO2. Such an assumption is supported by the 3He/4He ratios measured in the gas phase, are between 0.89 and 2.68 times the atmospheric ratio (Ra). These ratios which are higher than that those expected for a pure crustal origin (≈0.02 Ra), indicating that 10 to 30% of the He has originated from the upper mantle. Release of deep-seated fluids having a mantle-derived component in a region without recent volcanic activity indicates that extensive neo-tectonic structures originating during the Alpine Orogeny are still active (i.e., the Chaves Depression).
    Description: Published
    Description: 49-56
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: reserved
    Keywords: CO2-rich thermomineral waters ; mantle volatiles ; isotopes ; Chaves geothermal system ; N-Portugal ; 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::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
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    Shifting styles of basaltic explosive activity during the 2002-03 eruption of Mt. Etna, Italy (2010)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The 2002–03 flank eruption of Etna was characterized by two months of explosive activity that produced copious ash fallout, constituting a major source of hazard and damage over all eastern Sicily. Most of the tephra were erupted from vents at 2750 and 2800 m elevation on the S flank of the volcano, where different eruptive styles alternated. The dominant style of explosive activity consisted of discrete to pulsing magma jets mounted by wide ash plumes, which we refer to as ash-rich jets and plumes. Similarly, ash-rich explosive activity was also briefly observed during the 2001 flank eruption of Etna, but is otherwise fairly uncommon in the recent history of Etna. Here, we describe the features of the 2002–03 explosive activity and compare it with the 2001 eruption in order to characterize ash-rich jets and plumes and their transition with other eruptive styles, including Strombolian and ash explosions, mainly through chemical, componentry and morphology investigations of erupted ash. Past models explain the transition between different styles of basaltic explosive activity only in terms of flow conditions of gas and liquid. Our findings suggest that the abundant presence of a solid phase (microlites) may also control vent degassing and consequent magma fragmentation and eruptive style. In fact, in contrast with the Strombolian or Hawaiian microlite-poor, fluidal, sideromelane clasts, ash-rich jets and plumes produce crystal-rich tachylite clasts with evidence of brittle fragmentation, suggesting that high groundmass crystallinity of the very top part of the magma column may reduce bubble movement while increasing fragmentation efficiency.
    Description: Published
    Description: 110-122
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: JCR Journal
    Description: reserved
    Keywords: Etna ; basaltic explosive activity ; ash-rich jet and plume ; tachylite ; sideromelane ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
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    SO2 flux from Stromboli during the 2007 eruption: Results from the FLAME network and traverse measurements (2010)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: SO2 fluxes emitted by Stromboli during the 27th February–2nd April 2007 effusive eruption were regularly measured both by an automatic network of scanning ultraviolet spectrometers and by traverse measurements conducted by boat and helicopter. The results from both methodologies agree reasonably well, providing a validation for the automatic flux calculations produced by the network. Approximately 22,000 t of SO2 were degassed during the course of the 35 day eruption at an average rate of 620 t per day. Such a degassing rate is much higher than that normally observed (150–200 t/d), because the cross-sectional area occupied by ascending degassed magma is much greater than normal during the effusion, as descending, degassed magma that would normally occupy a large volume of the conduit is absent. We propose that the hydrostatically controlled magma level within Stromboli's conduit is the main control on eruptive activity, and that a high effusion rate led to the depressurisation of an intermediate magma reservoir, creating a decrease in the magma level until it dropped beneath the eruptive fissure, causing the rapid end of the eruption. A significant decrease in SO2 flux was observed prior to a paroxysm on 15th March 2007, suggesting that choking of the gas flowing in the conduit may have induced a coalescence event, and consequent rapid ascent of gas and magma that produced the explosion.
    Description: Published
    Description: 214-220
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: SO2 flux ; Stromboli ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    Nitrogen Isotopes in Volcanic Fluids of Different Geodynamic Settings (2010)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Nitrogen isotopes , N2/36Ar and 3He/4He were measured in volcanic fluids within different geodynamic settings. Subduction zones are represented by Aeolian archipelago, Mexican volcanic belt and Hellenic arc, spreading zones – by Socorro island in Mexico and Iceland and hot spots by Iceland and Islands of Cabo Verde. The δ15N values, corrected for air contamination of volcanic fluids, discharged from Vulcano Island (Italy), highlighted the presence of heavy nitrogen (around +4.3 ±0.5‰). Similar 15N values (around +5‰), have been measured for the fluids collected in the Jalisco Block, that is a geologically and tectonically complex forearc zone of the northwestern Mexico [1]. Positive values (15N around +3‰) have been also measured in the volcanic fluids discharged from Nysiros island located in the Ellenic Arc characterized by subduction processes. All uncorrected data for the Socorro island are in the range of -1 to -2‰. The results of raw nitrogen isotope data of Iceland samples reveal more negative isotope composition (about -4.4‰). On the basis of the non-atmospheric N2 fraction (around 50%) the corrected data of 15N for Iceland are around -16‰, very close to the values proposed by [2]. In a volcanic gas sample from Fogo volcano (Cabo Verde islands) we found a very negative value: -9.9‰ and -15‰ for raw and corrected values, respectively.
    Description: Published
    Description: Davos, Switzerland
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: open
    Keywords: Nitrogen Isotopes ; Subduction ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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  • 8
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    Insights into fluid circulation across the Pernicana Fault (Mt. Etna, Italy) and implications for flank instability (2010)
    Elsevier B.V.
    Details
    Publication Date: 2017-04-04
    Description: We conducted geophysical–geochemical measurements on a ∼2 kmN–S profile cutting across the Pernicana Fault, one of the most active tectonic features on the NE flank of Mt. Etna. The profile passes from the unstable E flank of the volcano (to the south) to the stable N flank and significant fluctuations in electrical resistivity, self-potential, and soil gas emissions (CO2, Rn and Th) are found. The detailed multidisciplinary analysis reveals a complex interplay between the structural setting, uprising hydrothermal fluids, meteoric fluids percolating downwards, ground permeability, and surface topography. In particular, the recovered fluid circulation model highlights that the southern sector is heavily fractured and faulted, allowing the formation of convective hydrothermal cells. Although the existence of a hydrothermal system in a volcanic area does not surprise, these results have great implications in terms of flank dynamics at Mt. Etna. Indeed, the hydrothermal activity, interacting with the Pernicana Fault activity, could enhance the flank instability. Our approach should be further extended along the full extent of the boundary between the stable and unstable sectors of Etna for a better evaluation of the geohazard in this active tectonic area.
    Description: This work was partly financed by the DPC-INGV FLANK and LAVA Projects.
    Description: Published
    Description: 137–142
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: reserved
    Keywords: Pernicana Fault ; fluid circulation ; structural geology ; Etna ; magnetic ; electrical methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.02. Exploration geophysics::04.02.04. Magnetic and electrical methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.05. Downhole, radioactivity, remote sensing, and other methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.07. Instruments and techniques ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.07. Rock geochemistry ; 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::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.08. Risk::05.08.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    Visualising volcanic gas plumes with virtual globes (2010)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The recent availability of small, cheap ultraviolet spectrometers has facilitated the rapid deployment of automated networks of scanning instruments at several volcanoes, measuring volcanic SO2 gas flux at high frequency. These networks open up a range of other applications, including tomographic reconstruction of the gas distribution which is of potential use for both risk mitigation, particularly to air traffic, and environmental impact modelling. Here we present a methodology for visualising reconstructed plumes using virtual globes, such as GoogleEarth, which allows animations of the evolution of the gas plume to be displayed and easily shared on a common platform. We detail the process used to convert tomographically reconstructed cross-sections into animated gas plume models, describe how this process is automated and present results from the scanning network around Mt.Etna, Sicily. We achieved an average rate of one frame every12 min, providing a good visual representation of the plume which can be examined from all angles. Increating these models, an approximation to turbulent diffusion in the atmosphere was required. To this end we derived the value of the turbulent diffusion coefficient for quiescent conditions near Etna to be around 200–500 m2s-1.
    Description: Published
    Description: 1837-1842
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Volcanic Plumes ; Tomography ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
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    The role of syn-eruptive vesiculation on explosive basaltic activity at Mt. Etna, Italy (2010)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We investigated the dynamics of explosive activity at Mt. Etna between 31 August and 15 December 2006 by combining vesicle studies in the erupted products with measurements of the gas composition at the active, summit crater. The analysed scoria clasts present large, connected vesicles with complex shapes and smaller, isolated, spherical vesicles, the content of which increases in scoriae from the most explosive events. Gas geochemistry reports CO2/SO2 and SO2/HCl ratios supporting a deep-derived gas phase for fire-fountain activity. By integrating results from scoria vesiculation and gas analysis we find that the highest energy episodes of Mt. Etna activity in 2006 were driven by a previously accumulated CO2-rich gas phase but we highlight the lesser role of syn-eruptive vesicle nucleation driven by water exsolution during ascent. We conclude that syn-eruptive vesiculation is a common process in Etnean magmas that may promote a deeper conduit magma fragmentation and increase ash formation.
    Description: Published
    Description: 265-269
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: reserved
    Keywords: Etna ; fire-fountains ; vesicle textures ; volcanic degassing ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 11
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    The feeding system of Agnano–Monte Spina eruption (Campi Flegrei, Italy): Dragging the past into present activity and future scenarios (2010)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Magmatic processes triggering eruptions at Campi Flegrei caldera (southern Italy) and their relationships with the widespread emissions of fluids and caldera unrest episodes, are poorly constrained. The 4.1 ka B.P. Agnano–Monte Spina eruption, the reference event for a future large-size explosive eruption at Campi Flegrei, was investigated to shed light, through melt inclusion and isotope analyses, on the geochemical processes operating in the plumbing system. Chemical and isotopic data on whole rocks and glasses suggest that at least two magma batches mixed during the course of the eruption. Melt inclusion data highlight the pre-eruption storage conditions of two magmatic end-members. One end-member is like the less differentiated (shoshonitic) Campi Flegrei erupted magma, while the other could be a residual of the Neapolitan Yellow Tuff magma. Mixing between these two components was driven by a large gas phase which sustained the ascent of magmas of deep provenance. The H2O and CO2 contents in pyroxene-hosted melt inclusions yield entrapment pressures between 107 and 211 MPa, corresponding to depths between 4 and 8 km. The degassing trends reveal two extreme patterns. One pattern, already documented in the literature, is the volatile signature of poorly differentiated magmas ascending from more than 8 km depth, while the other is related to a gas-dominated magma, flushed by a CO2-rich gas phase partly released from the deep reservoir. This study provides a conceptual frame for unrest phases at Campi Flegrei, such as the 1982–84 event. Uplift phases can be related to closed-system ascent of magmas and fluids from more than 8 km depth, and their emplacement at shallow levels. This leads the shallow system to store, and then progressively release, the accumulated gas. In this view, both unrest episodes and eruptions could be strongly influenced by both the achievement of a critical upper limit of gas storage in the shallow magmatic reservoir and the stress and fracturing state of the roof rocks. The present results help to constrain the pre-eruptive conditions expected at Campi Flegrei caldera in case of a future large-size eruptive event.
    Description: In press
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Sr and Nd isotopes ; Melt inclusions ; Gas flushing ; Magma mixing ; Bradyseismic crises ; Explosive eruptions ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
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    The pre-eruptive volatile contents of recent basaltic and pantelleritic magmas at Pantelleria (Italy) (2010)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Pantelleria Island, located in the Sicily Channel Rift Zone (Italy), is the type locality for the peralkaline rhyolitic rocks called pantellerites. In the last 50 ka, after the large Green Tuff caldera-forming eruption, volcanic activity at Pantelleria has consisted of effusive and explosive eruptions mostly vented inside and along the rim of the caldera and producing silicic lava flows, lava domes and poorly dispersed pantelleritic pumice fall deposits. Basaltic cinder cones and lava flows are only present outside the caldera in the NW sector of the island. The most recent basaltic (Cuddie Rosse, 20 ka) and pantelleritic (Cuddia Randazzo and Cuddia del Gallo, 6 ka) pyroclastic products were sampled to investigate magmatic volatile contents through the study of melt inclusions. The melt inclusions in pyroxene and olivine phenocrysts of Cuddie Rosse scoriae have an alkali basalt composition. The dissolved volatiles comprise 0.9–1.6 wt.% H2O, several hundred ppm of CO2, 1600–2000 ppm of sulphur and 500–900 ppm of chlorine. The water–carbon dioxide couple gives a confining pressure 2 kbar prior to the eruption. This result indicates that episodes of magma ponding and crystallization occurred in the upper crust prior to eruption. The melt inclusions in feldspar, fayalite and aenigmatite phenocrysts of Cuddia del Gallo and Cuddia Randazzo pumice have a pantelleritic composition (Agpaitic Indices 1.3–2.1), up to 4.4 wt.% H2O, 8700 ppm Cl, 6000 ppm F, and CO2 below the detection limit. Sulphur averaging 420 ppm has been measured in Cuddia Randazzo melt inclusions. These data indicate relatively high volatile contents for these low-energy Strombolian-type eruptions. Melt inclusions in Cuddia del Gallo pumice show the most evolved composition (Agpaitic Indices 2–2.1) and the highest volatile content, in agreement with fluid saturation conditions in the magma chamber prior to the eruption. This implies a confining pressure of 1 kbar for the top of the pantelleritic reservoir. The composition of melt inclusions and mineralogical assemblage of Cuddia Randazzo pumice indicate that it has a lower evolutionary degree (Agpaitic Indices 1.3–1.8) and lower pre-eruptive Cl and H2O contents than Cuddia del Gallo pumice. An increase in pressure due to the exsolution of volatiles in the upper part of the pantelleritic reservoir may have triggered the Cuddia del Gallo explosive eruption. Evidence of widespread pre-eruptive mingling between trachytes and pantellerites suggests that the intrusion of trachytic magma into the pantelleritic reservoir likely played a major role in destabilizing the magma system just prior to the Cuddia Randazzo event.
    Description: In press
    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: Pantelleria ; peralkaline ; volatiles ; melt inclusions ; eruptive style ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 13
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    Anomalous fluid emission of a deep borehole in a seismically active area of Northern Apennines (Italy) (2010)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The Miano borehole of 1047 m depth is located close to the river Parma in the Northern Apennines, Italy. A measuring station is installed to observe the discharge of fluids continuously since November 2004. The upwelling fluid of this artesian well is a mixture of thermal water and methane as main components. In non-seismogenic areas, we would expect a relative constant fluid emission perhaps overlaid with long term variations from that kind of deep reservoirs during the time. However, the continuously record of the fluid emission, in particular the water discharge, the gas flow rate and the water temperature, show periods of stable values interrupted by anomalous periods of fluctuations in the recorded parameters. The anomalous variations of these parameters are of low amplitude in comparison to the total values but significant in their long-term trend. Meteorological influences of rain and barometric pressure were not detected in recorded data probably due to reservoir depth and relatively high reservoir overpressure. Influences due to the ambient temperature after the discharge were evaluated by statistical analysis. We consider that recorded changes in fluid emission parameters can be interpreted as a mixing process of different fluid components in depth by variations in pore pressure as result of seismogenic stress variation. Local seismicity was analyzed in comparison to fluid’s physico-chemical data. The analysis supports the idea of an influence to fluid transport conditions due to geodynamic processes exist. Water temperature data show frequent anomalies probably connected with possible precursory phenomena of local seismic events.
    Description: In press
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: open
    Keywords: Fluids ; Earthquakes ; Continous monitoring ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
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  • 14
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    Dike emplacement and flank instability at Mount Etna: Constraints from a poro-elastic-model of flank collapse (2010)
    Elsevier B.V.
    Details
    Publication Date: 2017-04-04
    Description: Many volcanic edifices are subject to flank failure, usually produced by a combination of events, rather than any single process. From a dynamic point of view, the cause of collapse can be divided into factors that contribute to an increase in shear stress, and factors that contribute to the reduction in the friction coefficient μ of a potential basal failure plane. We study the potential for flank failure at Mount Etna considering a schematic section of the eastern flank, approximated by a wedge-like block. For such geometry, we perform a (steady state) limit equilibrium analysis: the resolution of the forces parallel to the possible basal failure plane allows us to determine the total force acting on the potentially unstable wedge. An estimate of the relative strength of these forces suggests that, in first approximation, the stability is controlled primarily by the balance between block weight, lithostatic load and magmatic forces. Any other force (sea load, hydrostatic uplift, and the uplift due to mechanical and thermal pore-fluid pressure) may be considered of second order. To study the model sensitivity, we let the inferred slope α of the basal surface failure vary between −10° and 10°, and consider three possible scenarios: no magma loading, magmastatic load, and magmastatic load with magma overpressure. We use error propagation to include in our analysis the uncertainties in the estimates of the mechanics and geometrical parameters controlling the block equilibrium. When there is no magma loading, the ratio between destabilizing and stabilizing forces is usually smaller than the coefficient of friction of the basal failure plane. In the absence of an initiating mechanism, and with the nominal values of the coefficient of friction μ=0.7±0.1 proposed, the representative wedge will remain stable or continue to move at constant speed. In presence of magmastatic forces, the influence of the lateral restraint decreases. If we consider the magmastatic load only, the block will remain stable (or continue to move at constant speed), unless the transient mechanical and thermal pressurization significantly decrease the friction coefficient, increasing the instability of the flank wedge for αN5° (seaward dipping decollement). When the magma overpressure contribution is included in the equilibrium analysis, the ratio between destabilizing and stabilizing forces is of the same order or larger than the coefficient of friction of the basal failure plane, and the block will become unstable (or accelerate), especially in the case of the reduction in friction coefficient. Finally, our work suggests that the major challenge in studying flank instability at Mount Etna is not the lack of an appropriate physical model, but the limited knowledge of the mechanical and geometrical parameters describing the block equilibrium.
    Description: This work was funded by Istituto Nazionale di Geofisica e Vulcanologia (INGV) and the Italian Dipartimento per la Protezione Civile (DPC) (DPC-INGV project V4 “Flank”).
    Description: In press
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Etna ; dike intrusion ; flank instability ; poro-elasticity ; analytical modelling ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.01. Computational geophysics::05.01.99. General or miscellaneous ; 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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  • 15
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    Magma dynamics of 2007 Stromboli effusive eruption as revealed by high precision location of seismic events. (2010)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Stromboli is considered one of the most active volcanoes in the world, and its persistent but moderate explosive activity is only interrupted by occasional episodes of more vigorous activity accompanied by lava flows. A new effusive eruption began in late February, 2007 and was characterised by intense seismic activity throughout the whole period. The accurate seismic signals analysis showed the presence of families of events with similar waveform signatures (i.e. multiplets) located beneath the crater region. Since traditional location techniques do not allow obtaining reliable hypocentres, our analysis focused on high precision locations of the seismicity, in order to better define the source geometry of the events. Hypocentres, therefore, have been relocated considering two steps: the first, based on a robust probabilistic approach, is used to find the absolute position of the clusters; the second exploits a master-event concept for the relative location of the events. Finally, the shape of the clusters and the temporal migration of the foci were correlated with the eruptive phases. The results show that the occurrence of a cluster of events is related to the opening and closure of a vent opened in the Sciara del Fuoco slope and, in particular, to the intrusion of a dike injected by central conduit in a radial direction, whereas another cluster lies in a narrow vertical volume positioned under the crater area. The geometry of the clusters suggests a source region depicting the shallower feeding system. Overall, the results highlight that the high precision locations method is an efficient and quick tool to obtain a better understanding of the magmatic processes occurring during an ongoing eruption.
    Description: Published
    Description: 405-415
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: eruption ; high precision location ; seismic swarms ; magma dynamics ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 16
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    Geochemistry of fluids discharged over the seismic area of the Southern Apennines (Calabria region, Southern Italy): Implications for Fluid-Fault relationships (2010)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The first comprehensive geochemical data-set of the fluids circulating over a 14,000 km2-wide seismicprone area of the Southern Apennines, Calabria Region (Italy), is presented here. The geochemical investigations were carried out with the twofold aim of constraining the origin and interactions of the circulating fluids and to investigate possible relationships with local faults. Sixty samples of both thermal and cold waters were collected, from which the dissolved gases were extracted. The geochemical features of the water samples display different types and degrees of water–rock interactions, irrespective of the outlet temperature. The calculated equilibrium temperatures of the thermal waters (60–160 C) and the low heat flow of thewhole study area, are consistent with a heating process due to deep water circulation and rapid upflow through lithospheric structures. The composition of the dissolved gases reveals that crustal-originating gases (N2 and CO2-dominated) feed all the groundwaters. The 3He/4He ratios of the dissolved He, in the range of 0.03–0.22Rac for the thermal waters and 0.05–0.63Rac for the cold waters (Rac = He isotope ratio corrected for atmospheric contamination), are mainly the result of a two-component (radiogenic and atmospheric) mixing, although indications of mantle-derived He are found in some cold waters. As the study area had been hit by 18 of the most destructive earthquakes (magnitude ranging from 5.9 to 7.2) occurring over a 280-a time span (1626–1908) in the Southern Apennines, the reported results on the circulating fluids may represent the reference for a better inside knowledge of the fault-fluid relationships and for the development of long-term geochemical monitoring strategies for the area.
    Description: Published
    Description: 540–554
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: open
    Keywords: Fluids ; Geochemistry ; Faults ; Seismicity ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration
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  • 17
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    Unravelling the processes controlling gas emissions from the central and northeast craters of Mt. Etna (2010)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We measured volcanic gas emissions from the northeast crater (NEC) and central crater (CC) of Mount Etna on 21st July 2008, and 3rd and 31st August 2009, using a novel, lightweight open-path Fourier transform infrared spectrometry (OP-FTIR) in active mode with a portable infrared lamp. Contemporaneously we measured the SO2 flux of the total gas emission released by the combined summit craters 14 km downwind and the SO2 flux emitted by the NEC measured at the summit. Combining these data we determined the flux of the major volcanic components H2O, CO2, SO2, HCl and HF emitted individually from CC and NEC craters. The results reveal similar SO2/HCl ratios but distinct CO2/SO2 ratios (1.3 and 10.9 for NEC and CC, respectively) and an order of magnitude greater CO2 flux from the CC compared with the NEC. A simple model in which the NEC branches from a central feeding conduit at a depth of ~2 km can reproduce these observations. We highlight that in such a system short-term variations in CO2/SO2 ratios at each crater can occur due to minor variations in the magma/gas flux entering each conduit at the branch, without an overall change in magma supply. CO2/ SO2 variations measured at individual craters may therefore be unrepresentative of the volcanic system and require cautious interpretation. Monitoring of the total CO2 and SO2 fluxes emitted from each crater is, on the contrary, an optimal monitoring strategy and can be achieved using a combination of CO2/SO2 instruments and SO2 imaging cameras
    Description: INGV-DPC “Sicilia” Project (Gas plumeTask).
    Description: Published
    Description: 368-376
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: magma degassing, OP-FTIR, Mt. Etna ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 18
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    Anomalous fluid emission of a deep borehole in a seismically active area of Northern Apennines (Italy) (2010)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The Miano borehole, 1047 m deep, is located close to the river Parma in the Northern Apennines, Italy. A measuring station has been installed to observe the discharge of fluids continuously since November 2004. The upwelling fluid of this artesian well is a mixture of thermal water and CH4 as main components. In non-seismogenic areas, a relatively constant fluid emission would be expected, perhaps overlaid with long term variations from that kind of deep reservoir over time. However, the continuous record of the fluid emission, in particular the water discharge, the gas flow rate and the water temperature, show periods of stable values interrupted by anomalous periods of fluctuations in the recorded parameters. The anomalous variations of these parameters are of low amplitude in comparison to the total values but significant in their long-term trend. Meteorological effects due to rain and barometric pressure were not detected in recorded data probably due to reservoir depth and relatively high reservoir overpressure. Influences due to the ambient temperature after the discharge were evaluated by statistical analysis. Our results suggest that recorded changes in fluid emission parameters can be interpreted as a mixing process of different fluid components at depth by variations in pore pressure as a result of seismogenic stress variation. Local seismicity was analyzed in comparison to the fluid physico-chemical data. The analysis supports the idea that an influence on fluid transport conditions due to geodynamic processes exists. Water temperature data show frequent anomalies probably connected with possible precursory phenomena of local seismic events.
    Description: Published
    Description: 555–571
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: open
    Keywords: Fluids ; Seismicity ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 19
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    Multiple resolution seismic attenuation imaging at Mt. Vesuvius (2010)
    Elsevier
    Details
    Publication Date: 2019-03-05
    Description: A three-dimensional S wave attenuation tomography of Mt. Vesuvius has been obtained with multiple measurements of coda-normalized S-wave spectra of local small magnitude earthquakes.We used 6609 waveforms, relative to 826 volcano-tectonic earthquakes, located close to the crater axis in a depth range between 1 and 4 km (below the sea level), recorded at seven 3-component digital seismic stations. We adopted a two-point ray-tracing; rays were traced in an high resolution 3-D velocity model. The spatial resolution achieved in the attenuation tomography is comparable with that of the velocity tomography (we resolve 300m side cubic cells). We statistically tested that the results are almost independent from the radiation pattern. We also applied an improvement of the ordinary spectral-slope method to both P- and S-waves, assuming that the differences between the theoretical and the experimental high frequency spectral-slope are only due to the attenuation effects. Consequently we could check the codanormalization method also comparing the S attenuation image with the P attenuation image. The images were obtained inverting the spectral data with a multiple resolution approach. Results have shown the general coincidence of low attenuation with high velocity zones. The joint interpretation of velocity and attenuation images allows us to interpret the low attenuation zone intruding toward the surface until a depth of 500m below the sea level as related to the residual part of solidified magma from the last eruption. In the depth range between −700 and −2300 images are consistent with the presence of multiple acquifer layers. No evidence of magma patches greater than the minimum cell dimension (300m) has been found. A shallow P wave attenuation anomaly (beneath the southern flank of the volcano) is consitent with the presence of gas saturated rocks. The zone characterized by the maximum seismic energy release cohincides with a high attenuation and low velocity volume, interpreted as a cracked medium.
    Description: Published
    Description: 17–32
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Attenuation tomography ; Mt. Vesuvius ; Coda normalization method ; Spectral slope ; Multi resolution inversion ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
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  • 20
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    Fault plane orientations of microearthquakes at Mt. Etna from theinversion of P-wave rise times (2010)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A crucial point in the analysis of tectonic earthquakes occurring in a volcanic area is the inference of the orientation of the structures along which the ruptures occur. These structures represent zones of weakness which could favor the migration of melt toward the surface and the assessment of their geometry is a fundamental step toward efficient evaluation of volcanic risk. We analyzed a high-quality dataset of 171 lowmagnitude, tectonic earthquakes that occurred at Mt. Etna during the 2002–2003 eruption. We applied a recently developed technique aimed at inferring the source parameters (source size, dip and strike fault) and the intrinsic quality factor Qp of P waves from the inversion of rise times. The technique is based on numerically calibrated relationships among the rise time of first P waves and the source parameters for a circular crack rupturing at a constant velocity. For the most of the events the directivity source effect did not allow us to constrain the fault plane orientation. For a subset of 45 events with well constrained focal mechanisms we were able to constrain the “true” fault plane orientation. The level of resolution of the fault planes was assessed through a non linear analysis based on the random deviates technique. The significance of the retrieved fault plane solutions and the fit of the assumed source model to data were assessed through a χ-square test. Most of the retrieved fault plane solutions agree with the geometrical trend of known surface faults. The inferred source parameters and Qp are in agreement with the results of previous studies
    Description: Published
    Description: 247-256
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: rise time ; directivity ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 21
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    The growth and erosion of cinder cones in Guatemala and El Salvador: Models and statistics (2010)
    Elsevier B.V.
    Details
    Publication Date: 2017-04-04
    Description: Morphologic data for 147 cinder cones in southernGuatemala andwestern El Salvador are comparedwith data from 21 the San Francisco volcanic field, Arizona (USA), Cima volcanic field, California (USA), Michoácan–Guanajuato 22 volcanic field, Mexico, and the Lamongan volcanic field, East Java. The Guatemala cones have an average height of 23 110+/−50m, an average basal diameter of 660+/−230m and an average top diameter of 180+/−150m. The 24 generalmorphology of these cones can be described by their average cone angle of slope (24+/−7), average height- 25 to-radius ratio (0.33+/−0.09) and their flatness (0.24+/−0.18). Although the mean values for the Guatemalan 26 cones are similar to those for other volcanic fields (e.g., San Francisco volcanic field, Arizona; Cima volcanic field, 27 California; Michoácan–Guanajuato volcanic field, Mexico; and Lamongan volcanic field, East Java), the range of 28 morphologies encompasses almost all of those observed worldwide for cinder cones. 29 Three new 40Ar/39Ar age dates are combined with 19 previously published dates for cones in Guatemala and El 30 Salvador. There is no indication that the morphologies of these cones have changed over the last 500–1000 ka. 31 Furthermore, a re-analysis of published data for other volcanic fields suggests that only in the Cima volcanic field (of 32 those studied) is there clear evidence of degradation with age. 33 Preliminary results of a numerical model of cinder cone growth are used to show that the range of morphologies 34 observed in the Guatemalan cinder cones could all be primary, that is, due to processes occurring at the time of 35 eruption.
    Description: Support for Walker was provided by NSF MARGINS grant OCE-0405666.
    Description: In press
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: cinder cones ; morphology ; age dating ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.99. General or miscellaneous ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 22
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    Dependence of clinopyroxene composition on cooling rate in basaltic magmas: Implications for thermobarometry (2010)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The compositional variation of clinopyroxene and the partitioning ofmajor elements between clinopyroxene and melt are estimated as a function of the cooling rate. Clinopyroxenes were crystallized under variable cooling regimes (15, 9.4, 3, 2.1, and 0.5 °C/min from1250 down to 1000 °C) and at isothermal conditions of 1000 °C from a basaltic composition at a pressure of 500 MPa under anhydrous and hydrous (H2O=1.3 wt.%) conditions. The clinopyroxene chemistry shows that, as the cooling rate increases, crystals are progressively depleted in Ca,Mg, Fe2+ and Si and enriched inNa, Fe3+, Al (mainlyAlIV), and Ti. Di andHd versus CaTs and CaFeTs forma continuous binary solid solution characterized by higher amounts of tschermakitic componentswith increasing cooling rate. Two parameters (DH=Di+Hd and TE=CaTs+CaFeTs+En) are calculated to describe the effect of cooling rate on the clinopyroxene composition. The variation of DH/TE with increasing cooling rate evidences the kinetic process induced by rapid cooling in basic rocks under hydrous and anhydrous conditions. Dynamic crystallization conditions affect the partitioning of major elements between clinopyroxene and melt; with increasing cooling rate, the value of crystal–melt partition coefficient departs from that obtained at the isothermal condition. However, in spite of these variations, the values of cpx–meltKdFe–Mg remain almost constant. Therefore, the Fe2–Mg exchange between clinopyroxene and melt is not suitable to prove the (dis)equilibrium conditions in basaltic coolingmagmas, giving rise to possiblemismatches in the application of thermobarometers. The results of our study are consistentwith that observed at themargin of dikes or inthe exterior portions of lavas, where the cooling rate is maximized and disequilibrium compositions of clinopyroxene have been found.
    Description: Published
    Description: 302-312
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: cooling rate ; clinopyroxene ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 23
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    Changes in the VLP seismic source during the 2007 Stromboli eruption (2010)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Aim of this paper is to identify variations in Very-Long-Period (VLP) source associated with eruptive style changes at Stromboli volcano (Italy) and to retrieve information about the shallow plumbing system that sustains the eruptive activity. We have considered a dataset of 74493 VLP events recorded during the period from January through August 2007, when an effusive eruption occurred (February 27–April 2).We performed a polarization analysis of the entire dataset and divided the considered period into four sub-periods on the basis of polarization characteristics. We then located the events and selected a subset of these events by applying a location quality threshold. The high quality locations demonstrate that during the effusive eruption the VLP sources first moved downward and then moved southwestward. To retrieve information about the geometry of the structures where the source processes take place, we further consider a subset of events and estimate their source mechanisms by using a moment tensor source function (MTSF) inversion technique. Inversion of the waveforms of the VLP events that occurred on February 27 allows us to obtain information about the dynamics of different source centroids distributed along different portions of the shallow magmatic conduits. The structure defined by the locations and source mechanisms shows a greater complexity compared with previous studies and their time variations give an insight into the kinematics of the eruption.
    Description: Published
    Description: 162–171
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: stromboli ; very-long-period events ; seismic source mechanism ; volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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