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  • 04. Solid Earth::04.08. Volcanology::04.08.01. Gases  (4)
  • 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy  (3)
  • Agu  (6)
  • American Institute of Physics (AIP)
  • Nature Publishing Group
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Publisher
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  • 1
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    On the relevance of Born theory in global seismic tomography (2007)
    Agu
    Details
    Publication Date: 2021-01-27
    Description: Does the application of seismic Born theory, as opposed to simpler ray theory, lead to an improvement in tomographic images of the Earth? In recent publications, Montelli et al. (2004a, 2004b) and van der Hilst and de Hoop (2005) among others have expressed opposite opinions. We propose a quantitative approach to the comparison of tomographic images, which we apply to the case of surface-wave phase velocity maps derived with Born vs. ray theory.
    Description: Published
    Description: L06302
    Description: JCR Journal
    Description: reserved
    Keywords: global seismic tomography ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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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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  • 3
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    Compressional velocity structure and anisotropy in the uppermost mantle beneath Italy and surrounding regions (2007)
    Agu
    Details
    Publication Date: 2017-04-04
    Description: Travel times of about 39,000 Pn arrivals recorded from regional earthquakes by the Italian Telemetered Seismic Network and by stations of nearby countries are inverted to image lateral variations of seismic velocity and anisotropy at subcrustal depth in Italy and surrounding regions. This method allows simultaneous imaging of variations of Pn velocity and anisotropy, as well as crustal thickness variations. The Po plain, the Adriatic Sea, and the Ionian Sea have normal to high Pn velocities. In contrast, lower velocities (7.9-8.0 km/s) are imaged in Italy beneath the western Alps, the northern Apennines, and eastern Sicily and nearby Calabria, as well as in northern Albania and beneath the Pannonian basin. Low Pn velocities beneath the northern Apennines correlate with present-day extension and may have resulted from thermal anomalies in the uppermost mantle due to delamination processes. Low velocities are consistent with the high-attenuation zone inferred in the uppermost mantle beneath the internal Apennine units and the Tyrrhenian margin of the peninsula by Mele et al. [1996, 1997]. On the contrary, low velocities beneath the western Alps may be an apparent effect due to the abrupt thickening of the crustal roots. Pn velocity is anisotropic in the study area with a maximum amplitude of ± 0.2 km/s. The largest anisotropic velocity anomalies are observed along the major arc structures of Italy, i.e., the northern Apennines and the Calabrian Arc, indicating that these features are controlled by uppermost mantle processes. The anisotropy anomaly along the Calabrian Arc extends as far as Albania but ends abruptly north of this area, suggesting that a lithospheric discontinuity is present along the northern Albanian border.
    Description: Published
    Description: 12,529-12,543
    Description: JCR Journal
    Description: reserved
    Keywords: Pn anisotropic tomography ; Italy ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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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)
    Type: article
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  • 6
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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)
    Type: article
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  • 7
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    A novel approach to estimate the eruptive potential and probability in open conduit volcanoes (2016)
    Nature Publishing Group
    Details
    Publication Date: 2017-04-04
    Description: In open conduit volcanoes, volatile-rich magma continuously enters into the feeding system nevertheless the eruptive activity occurs intermittently. From a practical perspective, the continuous steady input of magma in the feeding system is not able to produce eruptive events alone, but rather surplus of magma inputs are required to trigger the eruptive activity. The greater the amount of surplus of magma within the feeding system, the higher is the eruptive probability.Despite this observation, eruptive potential evaluations are commonly based on the regular magma supply, and in eruptive probability evaluations, generally any magma input has the same weight. Conversely, herein we present a novel approach based on the quantification of surplus of magma progressively intruded in the feeding system. To quantify the surplus of magma, we suggest to process temporal series of measurable parameters linked to the magma supply. We successfully performed a practical application on Mt Etna using the soil CO2 flux recorded over ten years.
    Description: Published
    Description: 30471
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 5V. Sorveglianza vulcanica ed emergenze
    Description: JCR Journal
    Description: restricted
    Keywords: eruptive potential ; eruptive probability ; open conduit volcanoes ; Etna ; Soil CO2 flux ; 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::04.08.06. Volcano monitoring ; 05. General::05.08. Risk::05.08.01. Environmental risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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