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  • Articles  (9)
  • 04. Solid Earth::04.08. Volcanology::04.08.01. Gases  (6)
  • 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution  (3)
  • Greece
  • AGU  (7)
  • Copernicus  (2)
  • American Association for the Advancement of Science
  • 2010-2014  (9)
  • 1980-1984
  • 1965-1969
  • 1925-1929
Collection
  • Articles  (9)
Source
Keywords
Publisher
Years
  • 2010-2014  (9)
  • 1980-1984
  • 1965-1969
  • 1925-1929
  • 2005-2009  (17)
Year
  • 1
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    Excess volatiles supplied by mingling of mafic magma at an andesite arc volcano (2010)
    AGU
    Details
    Publication Date: 2021-04-07
    Description: We present the results of a study of volcanic gases at Soufrière Hills Volcano, Montserrat, which includes the first spectroscopic measurements of the major gas species CO2 and H2S at this volcano using a Multisensor Gas Analyzer System (MultiGAS) sensor. The fluxes of CO2 and H2S were 640–2750 t/d and 84–266 t/d, respectively, during July 2008, during a prolonged eruptive pause. The flux of CO2 is similar to estimates for the entire arc from previous geochemical studies, while the measured H2S flux significantly alters our interpretation of the sulphur budget for this volcano. The fluxes of both sulphur and carbon show considerable excesses over that which can be supplied by degassing of erupted magma. We demonstrate, using thermodynamic models and published constraints on preeruptive volatile concentrations, that the gas composition and fluxes are best modeled by mixing between (1) gases derived from isobaric quenching of mafic magma against cooler andesite magma at depth and (2) gases derived from shallower rhyolitic interstitial melt within the porpyritic andesite. The escape of deep‐derived gases requires pervasive permeability or vapor advection extending to several kilometers depth in the conduit and magma storage system. These results provide more compelling evidence for both the contribution of unerupted mafic magma to the volatile budget of this andesitic arc volcano and the importance of the intruding mafic magma in sustaining the eruption. From a broader perspective, this study illustrates the importance and role of underplating mafic magmas in arc settings. These magmas play an important role in triggering and sustaining eruptions and contribute in a highly significant way to the volatile budget of arc volcanoes.
    Description: Published
    Description: Q04005
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: restricted
    Keywords: magma degassing ; thermodynamics ; volcanic gases ; Soufriere Hills ; 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)
    Type: article
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  • 2
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    Static chamber methane flux measurements in volcanic/geothermal areas: preliminary data from Sousaki and Nisyros (Greece) (2010)
    Copernicus
    Details
    Publication Date: 2017-04-04
    Description: Methane plays an important role in the Earth’s atmospheric chemistry and radiative balance being the second most important greenhouse gas after carbon dioxide. Methane is released to the atmosphere by a wide number of sources, both natural and anthropogenic, with the latter being twice as large as the former (IPCC, 2007). It has recently been established that significant amounts of geological methane, produced within the Earth’s crust, are currently released naturally into the atmosphere (Etiope, 2004). Active or recent volcanic/geothermal areas represent one of these sources of geological methane. But due to the fact that methane flux measurements are laboratory intensive, very few data have been collected until now and the contribution of this source has been generally indirectly estimated (Etiope et al., 2007). The Greek territory is geodynamically very active and has many volcanic and geothermal areas. Here we report on methane flux measurements made at two volcanic/geothermal systems along the South Aegean volcanic arc: Sousaki and Nisyros. The former is an extinct volcanic area of Plio-Pleistocene age hosting nowadays a low enthalpy geothermal field. The latter is a currently quiescent active volcanic system with strong fumarolic activity due to the presence of a high enthalpy geothermal system. Both systems have gas manifestations that emit significant amounts of hydrothermal methane and display important diffuse carbon dioxide emissions from the soils. New data on methane isotopic composition and higher hydrocarbon contents point to an abiogenic origin of the hydrothermal methane in the studied systems. Measured methane flux values range from –48 to 29,000 (38 sites) and from –20 to 1100 mg/mˆ2/d (35 sites) at Sousaki and Nisyros respectively. At Sousaki measurement sites covered almost all the degassing area and the diffuse methane output can be estimated in about 20 t/a from a surface of about 10,000 mˆ2. At Nisyros measurements covered the Stephanos and Kaminakia areas, which represent only a part of the entire degassing area. The two areas show very different methane degassing pattern with latter showing much higher flux values. Methane output can be estimated in about 0.25 t/a from an area of about 30,000 mˆ2 at Stephanos and about 1 t/a from an area of about 20,000 mˆ2 at Kaminakia. The total output from the entire geothermal system of Nisyros probably should not exceed 2 t/a.
    Description: Published
    Description: Vienna, Austria
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: open
    Keywords: methane output ; diffuse degassing ; volcanic/hydrothermal systems ; Greece ; 01. Atmosphere::01.01. Atmosphere::01.01.03. Pollution ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 05. General::05.08. Risk::05.08.01. Environmental risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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  • 3
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    Environmental impact of Mt. Etna’s degassing: volcanogenic trace elements bioaccumulation in two endemic plant species (Senecio aethnensis and Rumex aethnensis) (2010)
    Copernicus
    Details
    Publication Date: 2017-04-04
    Description: A biomonitoring survey, above tree line level, using two endemic species (Senecio aethnensis and Rumex aethnensis) was performed on Mt. Etna, in order to evaluate the dispersion and the impact of volcanic atmospheric emissions. Samples of leaves were collected in summer 2008 from 30 sites in the upper part of the volcano (1500- 3000 m a.s.l). Acid digestion of samples was carried out with a microwave oven, and 44 elements were analyzed by using plasma spectrometry (ICP-MS and ICP-OES). The highest concentrations of all investigated elements were found in the samples collected closest to the degassing craters, and in the downwind sector, confirming that the eastern flank of Mt. Etna is the most impacted by volcanic emissions. Leaves collected along two radial transects from the active vents on the eastern flank, highlight that the levels of metals decrease one or two orders of magnitude with increasing distance from the source. This variability is higher for volatile elements (As, Bi, Cd, Cs, Pb, Sb, Tl) than for more refractory elements (Al, Ba, Sc, Si, Sr, Th, U). The two different species of plants do not show significant differences in the bioaccumulation of most of the analyzed elements, except for lanthanides, which are systematically enriched in Rumex leaves. The high concentrations of many toxic elements in the leaves allow us to consider these plants as highly tolerant species to the volcanic emissions, and suitable for biomonitoring researches in the Mt. Etna area.
    Description: Published
    Description: Vienna, Austria
    Description: 4.4. Scenari e mitigazione del rischio ambientale
    Description: open
    Keywords: Mt. Etna ; biomonitoring ; Trace elements ; 01. Atmosphere::01.01. Atmosphere::01.01.03. Pollution ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 05. General::05.08. Risk::05.08.01. Environmental risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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  • 4
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    Unusually large magmatic CO2 gas emissions prior to a basaltic paroxysm (2010)
    AGU
    Details
    Publication Date: 2012-02-03
    Description: An edited version of this paper was published by AGU. Copyright (2010) American Geophysical Union.
    Description: The low‐intensity activity of basaltic volcanoes is occasionally interrupted by short‐lived but energetic explosions which, whilst frequently observed, are amongst the most enigmatic volcanic events in Nature. The combination of poorly understood and deep, challenging to measure, source processes make such events currently impossible to forecast. Here we report increases in quiescent degassing CO2 emissions (〉10,000 t/day) prior to a powerful explosive event on Stromboli volcano on 15 March 2007. We interpret such large CO2 flux as being sourced by passive gas leakage from a deeply (〉4 km) stored magma, whose depressurization, possibly caused by the onset of an effusive eruption on 28 February 2007, was the explosion trigger. Our observations suggest that continuous CO2 flux monitoring may allow anomalously large explosions to be accurately forecast at basaltic volcanoes.
    Description: Funding from INGV‐DPC project Paroxysm
    Description: Published
    Description: L17303
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: CO2, UV scanner, Stromboli ; 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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  • 5
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    Large amplitude variations recorded by an on‐fault seismological station during the L’Aquila earthquakes: Evidence for a complex fault‐induced site effect (2011)
    AGU
    Details
    Publication Date: 2012-02-03
    Description: A station (FAGN) installed on a segment of the fault system that generated the April 2009 L’Aquila earthquakes shows larger ground motions compared to nearby stations. Spectral ratios using 304 earthquakes result in a station amplification significantly varying event by event in the frequency band 1–8 Hz. The resulting pattern of amplitude dependence on causative earthquake location reveals that the strongest (up to a factor of 10) amplifications occur for tightly clustered aftershocks aligned with the fault dip beneath FAGN thus indicating a fault‐guided effect. Fault models are investigated in a grid‐search approach by varying velocity, Q, width and depth of the fault zone. Although the problem solution is not unique and there are strong trade‐offs among the model parameters, constraints from observations yield a deep trapping structure model where the most likely values of velocity reduction, Q and damage zone width are 25%, 20, and 280 m, respectively.
    Description: Published
    Description: L24305
    Description: 3.1. Fisica dei terremoti
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: reserved
    Keywords: L'Aquila earthquake ; fault zone ; trapped waves ; site amplification ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
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    CO2 degassing system of Stromboli volcano inferred by summit, peripheral and hydrothermal continuous measurements. (2010)
    AGU
    Details
    Publication Date: 2017-04-04
    Description: Stromboli is an open conduct volcano characterized by “Strombolian” activity. This activity is the result of a “delicate” dynamic equilibrium between continuous refilling of deep volatiles exsolved from the magma batch and superficial degassing. The volatiles, reaching the surface, interact with superficial fluids modifying peripheral and summit degassing processes. In particular, the main peripheral manifestations are represented by dissolved volatiles in the basal hydrothermal aquifer, as well as structurally controlled soil degassing at the lower parts of the volcanic edifice. Summit degassing is manifested by active (explosions from the conduct) and passive degassing (plume degassing from the conduct and diffuse soil degassing). During “normal” Strombolian activity this dynamic equilibrium allows the discharge of the volatiles in the atmosphere arriving from the depth. When the deep volatile flux increases, we observe that the system reacts by first increasing the diffuse volatile discharge from the superficial system. In fact, the result is the increase of Strombolian activity (frequency and energy of explosions due to the increase of the total volatiles pressure) and the increase of the total dissolved volatiles in the hydrothermal aquifer and soils anomalous flux. During overpressure of the plumbing system paroxistic activity is necessary to maintain the dynamic pressure equilibrium, allows to maintain the dynamic equilibrium between deep and superficial volatiles. In fact, through the opening of new fractures and consecutive lava flow or by major explosions and paroxysms the system decreases the total pressure of volatiles and restores the dynamic equilibrium of the Stromboli plumbing system. On the basis of the experiences acquired during the last two eruptions (2002-2003 and 2007) we improved our geochemical monitoring network by installing new equipments for monitoring, continuously, selected fluid manifestations located on the peripheral areas. In particular, we installed two automatic equipments for measuring dissolved CO2 in the thermal wells located in the N-E side of Stromboli (Stromboli village). In this way we covered wider area of fluid degassing of Stromboli volcano to better understand the relationships between the degassing regimes of the summit and basal hydrothermal systems.
    Description: Published
    Description: San Francisco CA, USA
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: open
    Keywords: CO2 flux ; Volcano monitoring ; Stromboli ; 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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  • 7
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    On the deterministic description of earthquakes (2011)
    AGU
    Details
    Publication Date: 2017-04-04
    Description: The quantitative estimate of earthquake damage due to ground shaking is of pivotal importance in geosciences, and its knowledge should hopefully lead to the formulation of improved strategies for seismic hazard assessment. Numericalmodels of the processes occurring during seismogenic faulting represent a powerful tool to explore realistic scenarios that are often far from being fully reproduced in laboratory experiments because of intrinsic, technical limitations. In this paper we discuss the prominent role of the fault governing model, which describes the behavior of the fault traction during a dynamic slip failure and accounts for the different, and potentially competing, chemical and physical dissipative mechanisms. We show in a comprehensive sketch the large number of constitutive models adopted in dynamic modeling of seismic events, and we emphasize their prominent features, limitations, and specific advantages. In a quantitative comparison, we show through numerical simulations that spontaneous dynamic ruptures obeying the idealized, linear slip‐weakening (SW) equation and a more elaborated rate‐ and state‐dependent friction law produce very similar results (in terms of rupture times, peaks slip velocity, developed slip, and stress drops), provided that the frictional parameters are adequately comparable and, more importantly, that the fracture energy density is the same. Our numerical experiments also illustrate that the different models predict fault slip velocity time histories characterized by a similar frequency content; a feeble predominance of high frequencies in the SW case emerges in the frequency ranges [0.3, 1] and [11, 50] Hz. These simulations clearly indicate that, even forgiving the frequency band limitation, it would be very difficult (virtually impossible) to discriminate between two different, but energetically identical, constitutive models, on the basis of the seismograms recorded after a natural earthquake.
    Description: Published
    Description: RG3002
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Earthquake mechanics ; constitutive equations ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
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    Hydrogen in the gas plume of an open‐vent volcano, Mount Etna, Italy (2011)
    AGU
    Details
    Publication Date: 2017-04-04
    Description: We report here on the first hydrogen determinations in the volcanic gas plume of Mount Etna, in Italy, which we obtained during periodic field surveys on the volcano’s summit area with an upgraded MultiGAS. Using a specific (EZT3HYT) electrochemical sensor, we resolved H2 concentrations in the plume of 1–3 ppm above ambient (background) atmosphere and derived H2‐SO2 and H2‐H2O plume molar ratios of 0.002–0.044 (mean 0.013) and 0.0001–0.0042 (mean 0.0018), respectively. Taking the above H2‐SO2 ratios in combination with a time‐averaged SO2 flux of 1600 Gg yr−1, we evaluate that Etna contributes a time‐averaged H2 flux of ∼0.65 Gg yr−1, suggesting that the volcanogenic contribution to the global atmospheric H2 budget (70,000–100,000 Gg yr−1) is marginal. We also use our observed H2‐H2O ratios to propose that Etna’s passive plume composition is (at least partially) representative of a quenched (temperatures between 750°C and 950°C) equilibrium in the gas‐magma system, at redox conditions close to the nickel‐nickel oxide (NNO) mineral buffer. The positive dependence between H2‐SO2, H2‐H2O, and CO2‐SO2 ratios suggests that H2 is likely supplied (at least in part) by deeply rising CO2‐rich gas bubbles, fluxing through a CO2‐depleted shallow conduit magma.
    Description: Published
    Description: B10204
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: JCR Journal
    Description: restricted
    Keywords: Hydrogen ; Mount Etna ; Open-vent volcano ; plume ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    The complex architecture of the 2009 MW 6.1 L’Aquila normal fault system (Central Italy) as imaged by 64,000 high-resolution aftershock locations. (2012)
    AGU
    Details
    Publication Date: 2020-02-25
    Description: On April 6th 2009, a MW 6.1 normal faulting earthquake struck the axial area of the Abruzzo region in Central Italy. We present high-precision hypocenter locations of an extraordinary dataset composed by 64,000 earthquakes recorded at a very dense seismic network of 60 stations operating for 9 months after the main event. Events span in magnitude (ML) between -0.9 to 5.9, reaching a completeness magnitude of 0.7. The dataset has been processed by integrating an accurate automatic picking procedure together with cross-correlation and double-difference relative location methods. The combined use of these procedures results in earthquake relative location uncertainties in the range of a few meters to tens of meters, comparable/lower than the spatial dimension of the earthquakes themselves). This data set allows us to image the complex inner geometry of individual faults from the kilometre to meter scale. The aftershock distribution illuminates the anatomy of the en-echelon fault system composed of two major faults. The mainshock breaks the entire upper crust from 10 km depth to the surface along a 14-km long normal fault. A second segment, located north of the normal fault and activated by two Mw〉5 events, shows a striking listric geometry completely blind. We focus on the analysis of about 300 clusters of co-located events to characterize the mechanical behavior of the different portions of the fault system. The number of events in each cluster ranges from 4 to 24 events and they exhibit strongly correlated seismograms at common stations. They mostly occur where secondary structures join the main fault planes and along unfavorably oriented segments. Moreover, larger clusters nucleate on secondary faults located in the overlapping area between the two main segments, where the rate of earthquake production is very high with a long-lasting seismic decay.
    Description: INGV
    Description: Published
    Description: San Francisco (CA) USA
    Description: 3.1. Fisica dei terremoti
    Description: open
    Keywords: Normal faulting earthquakes ; large dataset ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Oral presentation
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