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  • 04. Solid Earth::04.08. Volcanology::04.08.01. Gases  (5)
  • 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology  (3)
  • 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas  (3)
  • seeps
  • Agu  (6)
  • Blackwell Publishing Ltd  (4)
  • Nature Publishing Group
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Keywords
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  • 1
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    Influence of carbon dioxide on the large-scale dynamics of magmatic eruptions at Phlegrean Fields (Italy) (2007)
    Agu
    Details
    Publication Date: 2017-04-04
    Description: Carbon dioxide is the second most abundant volatile species in magmas after water (Johnson et al., 1994) but its role on eruption dynamics is still largely unknown. The effects of the presence of CO2 in the Agnano Monte Spina eruption (4100 BP, Phlegrean Fields, Italy) are here evaluated by simulating the eruption dynamics from the base of the volcanic conduit up into the atmosphere. The numerical simulations consider multiphase flow dynamics and couple the steady-state, one-dimensional magma ascent model of Papale (2001) and the transient, axisymmetric pyroclast dispersal model of Neri et al. (2003). The main input parameters of the models were based on eruptive conditions estimated from the deposits. A parametric study has been performed on H2O and CO2 concentrations in the erupted magma. The addition of CO2 results in increased volatile saturation pressure and complex non-linear changes in the conduit flow. Nonetheless, within the range of conditions explored, this volatile scarcely affects the eruption style and dynamics in the atmosphere, which are principally controlled by the H2O content. The different roles of the two volatiles in the large-scale eruption dynamics are mostly the result of the competing changes induced by CO2 on vent conditions.
    Description: Published
    Description: L06318
    Description: JCR Journal
    Description: reserved
    Keywords: carbon dioxide ; Phlegrean Fields ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Mechanisms of conduit plug formation: implications for Vulcanian explosions. (2007)
    Agu
    Details
    Publication Date: 2017-04-04
    Description: We explore physical mechanisms controlling formation of a confining conduit plug using 1D, steady-state numerical models of magma ascent. Model results for the welldocumented 1997 Vulcanian explosions at Soufrie`re Hills volcano were compared against subsurface conditions constrained by geophysical and petrologic analysis. We suggest that, if magma is permeable and overpressured and rock surrounding the conduit is permeable, degassing occurs both vertically and through conduit walls. This outgassing creates a region of low-vesicularity, dense magma near the surface (magma plug) which eventually seals the conduit and promotes system overpressure. Driving pressure increases with increasing magma flow rate, hindering volatile exsolution and shifting open-system degassing to shallower levels of the conduit. As a result, increasing magma flow rate for a fixed conduit width creates a vertically thinner plug and increases the magnitude and vertical extent of conduit overpressure. Plug thickness and density are also controlled by magma and edifice permeability
    Description: Published
    Description: L20302
    Description: JCR Journal
    Description: reserved
    Keywords: physical mechanisms ; magma ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 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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  • 3
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    Exploring the evolution of a volcanic seismic swarm: the case of the 2000 Izu Islands swarm (2007)
    Agu
    Details
    Publication Date: 2017-04-04
    Description: The goal of this paper is to yield physical constrains on the nature and evolution of a seismic swarm by means of a quantitative stochastic modeling of earthquakes occurrence. With this purpose, we fit different stationary and nonstationary stochastic ETAS models to the Izu Islands seismic swarm occurred in 2000. We find that a nonstationary model with background activity and p-value varying through time describes the observations better than other simpler ETAS models. The coherent fluctuations of these parameters and of the spatio-temporal earthquake distribution are interpreted in terms of a magma/fluids source process that evolves through outbursts of activity superimposed to low frequency variations. The results obtained suggest that suitable nonstationary ETAS modeling can be very useful to characterize the nature of the swarm source, and it may provide the basis to build a quantitative tool for tracking in almost real-time the evolution of a magma/fluids source.
    Description: Published
    Description: L07310
    Description: JCR Journal
    Description: reserved
    Keywords: volcanic seismic ; Izu Islands swarm ; 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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    Hydrothermal buffering of the SO2/H2S ratio in volcanic gases: Evidence from La Fossa Crater fumarolic field, Vulcano Island (2007)
    Agu
    Details
    Publication Date: 2017-04-04
    Description: Sulfur speciation in volcanic gases is a potentially valuable tracer of degassing processes at volcanoes. Hitherto, observations of sulfur speciation in volcanic gas plumes have however been limited both in number and quality. Here, we report on periodic measurements of SO2 to H2S proportions in the volcanic gases from La Fossa volcano (Vulcano Island) performed during 2004–2006, a period which encompasses two heating events of the fumarolic field in January–April 2005 and December 2005. Results indicate a systematic relative increase (by a factor of 2–6) of SO2 to H2S proportions in the fumaroles during the heating events, which we ascribe to a temperature increase in the mixing zone between magmatic and hydrothermal fluids. We also demonstrate that sulphur speciation in La Fossa fumaroles reflects re-equilibration within a poly-baric hydrothermal system, and that this hydrothermal re-equilibration erases the pristine SO2/H2S ratios of any magma-derived sulphur present.
    Description: Published
    Description: L21315
    Description: JCR Journal
    Description: reserved
    Keywords: volcanic gases ; Vulcano Island ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
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    CO2 flux measurements in volcanic areas using the dynamic concentration methods: the influence of the soil permeability (2007)
    Agu
    Details
    Publication Date: 2017-04-04
    Description: In order to evaluate the influence of soil permeability on soil CO2 flux measurements performed with the dynamic concentration method, several tests were carried out using soils characterized by different permeability values and flow rates. A special device was assembled in the laboratory to create a one-dimensional gas flow through a soil of known permeability. Using the advective-diffusion theory, a physical model to predict soil concentration gradients was also developed. The calculated values of CO2 concentrations at different depths were compared with those measured during the tests and a good agreement was found. Four soils with different gas permeability (3.6 10 2 to 1.23 102 mm2) were used. The CO2 flux values were varied from 0.1 kg m 2 d 1 up to 22 kg m 2 d 1. On the basis of these results, a new empirical equation for calculating very accurate soil CO2 flux from dynamic concentration and soil permeability values was proposed. As highlighted by the experimental data, the influence of soil permeability on CO2 flux measurements depends on various factors, of which the flow rate of the suction pump is the most important. Setting low values for the pumping flux (0.4–0.8 L min 1), the mean error due to soil permeability was lower than 5%. Finally, the method was tested by measuring the CO2 flux in a grid of 48 sampling sites on Vulcano (Aeolian Islands, Italy), and the global error, affecting the CO2 flux measurements in a real application, was evaluated.
    Description: Published
    Description: B05202
    Description: JCR Journal
    Description: reserved
    Keywords: CO2 flux measurements ; volcanic areas ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
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    Dynamic feeder dyke systems in basaltic volcanoes: the exceptional example o fthe 1809 Etna eruption (Italy) (2015)
    Nature Publishing Group
    Details
    Publication Date: 2017-04-04
    Description: In this paper, we describe the 1809 eruption of Mt. Etna, Italy, which represents one historical rare case in which it is possible to observe details of the internal structure of the feeder system. This is possible thanks to the presence of two large pit craters located in the middle of the eruptive fracture field that allow studying a section of the shallow feeder system. Along the walls of one of these craters, we analysed well-exposed cross sections of the uppermost 15–20 m of the feeder system and related volcanic products. Here, we describe the structure, morphology and lithology of this portion of the 1809 feeder system, including the host rock which conditioned the propagation of the dyke, and compare the results with other recent eruptions. Finally, we propose the dynamic model of the magma behaviour inside a laterally-propagating feeder dyke, demonstrating how this dynamic triggered important changes in the eruptive style (from effusive/Strombolian to phreatomagmatic) during the same eruption. Our results are also useful for hazard assessment related to the development of flank eruptions, potentially the most hazardous type of eruption from basaltic volcanoes in densely urbanized areas, such as Mt. Etna.
    Description: Published
    Description: 1-11
    Description: 2T. Tettonica attiva
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 3V. Dinamiche e scenari eruttivi
    Description: 4V. Vulcani e ambiente
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: N/A or not JCR
    Description: open
    Keywords: feeder dyke ; basaltic volcanoes ; flank eruptions ; Etna ; volcanic hazards ; sill ; volcanic rift ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 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::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    Diffuse hydrothermal methane output and evidence of methanotrophic activity within the soils at Sousaki (Greece) (2011)
    Blackwell Publishing Ltd
    Details
    Publication Date: 2017-04-04
    Description: Methane soil flux measurements have been made in 38 sites at the geothermal system of Sousaki (Greece) with the closed chamber method. Fluxes range from –47.6 to 29,150 mg m-2 d-1 and the diffuse CH4 output of the system has been estimated at 19 t a-1. Contemporaneous CO2 flux measurements showed a moderate positive correlation between CO2 and CH4 fluxes. Comparison of the CO2/CH4 soil flux ratios with the CO2/CH4 ratio of the gases of the main gas manifestations provided evidence for methanotrophic activity within the soil. Laboratory CH4 consumption experiments confirmed the presence of methanotrophic microorganisms in soil samples collected at Sousaki. Consumption was generally in the range from –4.9 to –38.9 pmolCH4 h-1 g-1 but could sometimes reach extremely high values (–33,000 pmolCH4 h-1 g-1.). These results are consistent with recent studies on other geothermal systems that revealed the existence of thermoacidophilic bacteria exerting methanotrophic activity in hot, acid soils, thereby reducing methane emissions to the atmosphere.
    Description: Published
    Description: 97–107
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: reserved
    Keywords: Sousaki ; accumulation chamber ; soil degassing ; hydrothermal systems ; methane output ; methanotrophic activity ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
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    Rapid differentiation in a sill-like magma reservoir: a case study from the campi flegrei caldera (2012)
    Nature Publishing Group
    Details
    Publication Date: 2017-04-04
    Description: In recent decades, geophysical investigations have detected wide magma reservoirs beneath quiescent calderas. However, the discovery of partially melted horizons inside the crust is not sufficient to put constraints on capability of reservoirs to supply cataclysmic eruptions, which strictly depends on the chemical-physical properties of magmas (composition, viscosity, gas content etc.), and thus on their differentiation histories. In this study, by using geochemical, isotopic and textural records of rocks erupted from the high-risk Campi Flegrei caldera, we show that the alkaline magmas have evolved toward a critical state of explosive behaviour over a time span shorter than the repose time of most volcanic systems and that these magmas have risen rapidly toward the surface. Moreover, similar results on the depth and timescale of magma storage were previously obtained for the neighbouring Somma-Vesuvius volcano. This consistency suggests that there might be a unique long-lived magma pool beneath the whole Neapolitan area.
    Description: Published
    Description: article 712
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: N/A or not JCR
    Description: open
    Keywords: magma ; campi flegrei caldera ; 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 ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    Seismic attenuation imaging of Campi Flegrei: Evidence of gas reservoirs, hydrothermal basins, and feeding systems (2010)
    Agu
    Details
    Publication Date: 2019-03-05
    Description: An edited version of this paper was published by AGU. Copyright (2010) American Geophysical Union.
    Description: Passive high‐resolution attenuation tomography is used here to image the geological structure in the first upper 4 km of the shallow crust beneath the Campi Flegrei caldera, southern Italy. The inverse Q was estimated for each source‐receiver path using the coda‐normalization method (S‐waves) and the slope decay method (P‐waves and S‐waves). Inversion was performed using a multi‐resolution method, which ensures a minimum cell‐size resolution of 500 m. The study of the resolution matrix as well as the synthetic tests guarantee an optimal reproduction of the input anomalies in the center of the caldera, between 0 and 3.5 km in depth. High attenuation vertical structures are connected at the surface with the main volcanological features (e.g., the Solfatara and Mofete fumarole fields), and depict vertical Q contrast imaging important geological structures, such as the La Starza fault. These high attenuation volumes extend between the surface and a depth of about 3 km, where a hard rock layer is imaged by the sharp contrast of the quality factors. The retrieved image of the Campi Flegrei has been jointly interpreted taking into account evidence from seismological, geological, volcanological and geochemical investigations. This analysis has allowed an unprecedented view of the feeding systems in this area, and in particular it recognizes the vertically extending, high attenuation structures that correspond to gas or fluid reservoirs beneath Pozzuoli‐Solfatara, Solfatara, Mofete‐Mt. Nuovo and Agnano. This high‐attenuation system is possibly connected with the magma sill revealed at about 7 km in depth by passive travel‐time tomography.
    Description: Published
    Description: B09312
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Campi Flegrei ; gas ; 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 ; 05. General::05.01. Computational geophysics::05.01.03. Inverse methods
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
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    Seismic footprints of shallow dyke propagation at Etna, Italy (2016)
    Nature Publishing Group
    Details
    Publication Date: 2017-04-04
    Description: One of the key issues in forecasting volcanic eruptions is to detect signals that can track the propagation of dykes towards the surface. Continuous monitoring of active volcanoes helps significantly in achieving this goal. The seismic data presented here are unique, as they document surface faulting processes close (tens to a few hundred meters) to their source, namely the dyke tip. They originated nearby - and under - a seismic station that was subsequently destroyed by lava flows during eruptive activity at Etna volcano, Italy, in 2013. On February 20, a ~600 m-long and ~120 m wide NW-SE fracture field opened at an altitude between 2750 and 2900 m. The consequent rock dislocation caused the station to tilt and offset the seismic signal temporarily. Data acquisition continued until the arrival of the lava flow that led to the breakdown of the transmission system. Shallow ground fracturing and repeated low-frequency oscillations occurred during two stages in which the seismic signal underwent a maximum offset ~2.57 E+04 nm/s. Bridging instrumental recordings, fieldwork and conceptual modelling, these data are interpreted as the seismic footprints of a magmatic dyke intrusion that moved at speed ~0.02 m/s (first stage) and 0.46 m/s (second stage).
    Description: This work was supported by the MED-SUV project, which has received funding from the European Union’s Seventh Programme for research, technological development and demonstration under grant agreement No 308665.
    Description: Published
    Description: 11908
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: dyke propagation ; Etna ; seismic signals ; ground fracturing ; conceptual modelling ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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