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  • 04. Solid Earth::04.08. Volcanology::04.08.01. Gases  (48)
  • 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
  • Earthquake source observations
  • INGV  (31)
  • Elsevier Science Limited  (28)
  • Wiley  (5)
  • Irkutsk : Ross. Akad. Nauk, Sibirskoe Otd., Inst. Zemnoj Kory
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
  • 2010-2014  (40)
  • 2005-2009  (24)
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Keywords
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Years
Year
  • 1
    Publication Date: 2021-06-22
    Description: Total CO2 output from soil gas and plume, discharged from the Stromboli Island, was estimated. The CO2 emission of the plume emitted from the active crater was estimated on the basis of the SO2 crater output and C/S ratio, while CO2 discharged through diffuse soil emission was quantified on the basis of 419 measurements of CO2 fluxes from the soil of the whole island, performed by using the accumulation chamber method. The results indicate an overall output of ≅416 t day−1 of CO2 from the island. The main contribution to the total CO2 output comes from the summit area (396 t day−1), with 370 t/day from the active crater and 26 t day−1 from the Pizzo sopra La Fossa soil degassing area. The release of CO2 from peripheral areas is ≅20 t day−1 by soil degassing (Scari area mainly). The result of the soil degassing survey confirms the persistence of the highest CO2 degassing areas located on the North-East crater side and Scari area.
    Description: Published
    Description: 52-60
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 4V. Vulcani e ambiente
    Description: JCR Journal
    Description: restricted
    Keywords: CO2 flux ; CO2 output ; Stromboli Island ; SO2 flux ; 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::04.08. Volcanology::04.08.01. Gases ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2017-04-04
    Description: Soil carbonates are key features in soils of arid and semiarid environment, playing an important role from pedogenetic, landscape history, paleoclimatic and environmental points of view. The objectives of this work were (i) to study pathways of pedogenic carbonate (PC) formation, (ii) to distinguish between lithogenic and pedogenic inorganic C by using the natural C isotope abundance, and (iii) to estimate the soil C pools in a gypsiferous semiarid Mediterranean environment (Sicily, Italy). Five soil pedons developed on calcareous and non-calcareous parent materials from Holocene (10,000 years BP) to Upper Tortonian (7.2–5.3 Ma BP) in age were surveyed. During field soil description, the highest stage of carbonate morphology was found in soils developed on non-calcareous Holocene colluvial deposits (youngest deposits in age) which also showed the highest amount of PC. The great amount of PC in soils developed on youngest deposits was ascribed to a soil–landscape relationships. Being located in a doline overhung by gypsum outcrops, precipitation of Ca2+ from gypsum dissolved by rainfall and biogenic CO2 is reliable. The significant positive relationship between soil organic C and pedogenic carbonates δ13C values confirms that PC was formed from biogenic CO2. Organic C pool in the first cubic meter of soil ranged from 17 to 42 kg, whilst pedogenic inorganic C pool from 2.8 to 30.7 kg. The estimated rate of inorganic C accumulation in soils developed on youngest deposits was 2.5 g m−3 y−1, whereas the rate was negligible on older parent material. The hypothesized pathways of PC formation were ex-novo precipitation of gypsum–Ca2+ and biogenic CO2 and dissolution of lithogenic CaCO3 and re-precipitation of Ca2+ with biogenic CO2. From an environmental prospective, investigated soils may act as a sink of C when Ca2+ from gypsum is available for the formation of pedogenic carbonates.
    Description: Published
    Description: 31-38
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: JCR Journal
    Description: restricted
    Keywords: Gypsiferous soils ; Soil carbonates ; Stable C isotopes ; Soil C pools ; Soil–landscape relationship ; 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
    Publication Date: 2017-04-04
    Description: Volatile metal(loid)s are known to be emitted from volcanoes worldwide.We tested the suitability of active moss monitoring for tracking volatilemetal(loid)s released fromthe fumarolic field on Vulcano Island, Italy, and differentiated fumaroles from other sources of gaseous and particulate trace elements such as sea spray and soil.Metal(loid) accumulation on the mosses per day did depend neither on the state of the exposed moss (dead or living) nor exposure time (3, 6, or 9 weeks). After collection, mosses were digested with either HNO3/H2O2 or deionized water and analyzed by ICP-MS.While for most elements both extraction methods yielded similar concentrations, higher concentrations were observed e.g. for Pb in the stronger HNO3/H2O2 extracts, indicating the presence of particles, which were not digested and removed by filtration in deionized water extracts. Due to their ubiquitous detection in comparable concentrations at all 23 moss monitoring stations all over the island, Li, Mg and Sr were attributed to sea spray origin. Iron, Co, W, V, Pb, Cr, Mo, and Ba occurred predominantly at the crater, where the soil was not covered by vegetation, and thus likely represent soil-borne particulate transport. Arsenic, Sb, S, Se, Tl, Bi, and I showed a clear concentration maximum within the fumarolic field. Concentrations gradually decreased along a transect in wind direction fromthe fumaroles, which confirms their volcanic origin. Activemossmonitoring thus proved to be an inexpensive and easy-to-apply tool for investigations of volcanic metal(loid) emissions and distributions enabling differentiation of trapped elements by their source of origin.
    Description: Published
    Description: 30–39
    Description: 4V. Vulcani e ambiente
    Description: JCR Journal
    Description: restricted
    Keywords: La Fossa crater ; particle transport ; biomonitoring ; volatilization ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 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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  • 4
    Publication Date: 2017-04-04
    Description: In this work we show that the main springs of the central Apennine transport a total amount of heat of ∼2.2 109 J s−1. Most of this heat (57%) is the result of geothermal warming while the remaining 43% is due to gravitational potential energy dissipation. This result indicates that a large area of the central Apennines is very hot with heat flux values 4300 mWm−2. These values are higher than those measured in the magmatic and famously geothermal provinces of Tuscany and Latium and about 1/3 of the total heat discharged at Yellowstone. This finding is surprising because the central Apennines have been thought to be a relatively cold area. Translated by CO2 rich fluids, this heat anomaly suggests the existence of a thermal source such as a large magmatic intrusion at depth. Recent tomographic images of the area support the presence of such an intrusion visible as a broad negative velocity anomaly in seismic waves. Our results indicate that the thermal regime of tectonically active areas of the Earth, where meteoric waters infiltrate and deeply circulate, should be revised on the basis of mass and energy balances of the groundwater systems.
    Description: Published
    Description: 65–74
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: restricted
    Keywords: heat flux ; CO2 Earth degassing ; central Apennine ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 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)
    Type: article
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  • 5
    Publication Date: 2022-06-10
    Description: Between January 2011 and April 2012, Santorini volcano (Greece) experienced a period of unrest characterised by the onset of detectable seismicity and caldera-wide uplift. This episode of inflation represented the first sizeable intrusion of magma beneath Santorini in the past 50 years. We employ a new approach using 222 Rn– δ 13 C systematics to identify and quantify the source of diffuse degassing at Santorini during the period of renewed activity. Soil CO 2 flux measurements were made across a network of sites on Nea Kameni between September 2010 and January 2012. Gas samples were collected in April and September 2011 for isotopic analysis of CO 2 ( δ 13 C), and radon detectors were deployed during September 2011 to measure ( 222 Rn). Our results reveal a change in the pattern of degassing from the summit of the volcano (Nea Kameni) and suggest an increase in diffuse CO 2 emissions between September 2010 and January 2012. High-CO 2 -flux soil gas samples have δ 13 C ∼ 0 .Using this value and other evidence from the literature we conclude that these CO 2 emissions from Santorini were a mixture between CO 2 sourced from magma, and CO 2 released by the thermal or metamorphic breakdown of crustal limestone. We suggest that this mixing of magmatic and crustal carbonate sources may account more broadly for the typical range of δ 13 CvaluesofCO 2 (from ∼− 4 to ∼+ 1 )in diffuse volcanic and fumarole gas emissions around the Mediterranean, without the need to invoke unusual mantle source compositions. At Santorini a mixing model involving magmatic CO 2 (with δ 13 C of − 3 ± 2 and elevated ( 222 Rn)/CO 2 ratios ∼ 10 5 –10 6 Bqkg − 1 )andCO 2 released from decarbonation of crustal limestone (with ( 222 Rn)/CO 2 ∼ 30–300 Bqkg − 1 ,and δ 13 Cof + 5 ) can account for the δ 13 C and ( 222 Rn)/CO 2 characteristics of the ‘high flux’ gas source. This model suggests ∼ 60% of the carbon in the high flux deep CO 2 end member is of magmatic origin. This combination of δ 13 Cand( 222 Rn) measurements has potential to quantify magmatic and crustal contributions to the diffuse outgassing of CO 2 in volcanic areas, especially those where breakdown of crustal limestone is likely to contribute significantly to the CO 2 flux
    Description: Published
    Description: 180-190
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: restricted
    Keywords: volcanic unrest ; soil gas measurements ; carbon isotopic analysis ; magmatic degassing ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
    Publication Date: 2024-05-09
    Description: Copahue volcano is part of the Caviahue–Copahue Volcanic Complex (CCVC),which is located in the southwestern sector of the Caviahue volcano-tectonic depression (Argentina–Chile). This depression is a pull-apart basin accommodating stresses between the southern Liquiñe–Ofqui strike slip and the northern Copahue–Antiñir compressive fault systems, in a back-arc setting with respect to the Southern Andean Volcanic Zone. In this study, we present chemical (inorganic and organic) and isotope compositions (δ13C-CO2, δ15N, 3He/4He, 40Ar/36Ar, δ13C-CH4, δD-CH4, and δD-H2O and δ18O-H2O) of fumaroles and bubbling gases of thermal springs located at the foot of Copahue volcano sampled in 2006, 2007 and 2012. Helium isotope ratios, the highest observed for a Southern American volcano (R/Ra up to 7.94), indicate a non-classic arc-like setting, but rather an extensional regime subdued to asthenospheric thinning. δ13C-CO2 values (from −8.8‰ to −6.8‰ vs. V-PDB), δ15N values (+5.3‰ to +5.5‰ vs. Air) and CO2/3He ratios (from 1.4 to 8.8 × 109) suggest that the magmatic source is significantly affected by contamination of subducted sediments. Gases discharged from the northern sector of the CCVC show contribution of 3He-poor fluids likely permeating through local fault systems. Despite the clear mantle isotope signature in the CCVC gases, the acidic gas species have suffered scrubbing processes by a hydrothermal system mainly recharged by meteoric water. Gas geothermometry in the H2O-CO2-CH4-CO-H2 system suggests that CO and H2 re-equilibrate in a separated vapor phase at 200°–220 °C. On the contrary, rock–fluid interactions controlling CO2, CH4 production from Sabatier reaction and C3H8 dehydrogenation seem to occur within the hydrothermal reservoir at temperatures ranging from 250° to 300 °C. Fumarole gases sampled in 2006–2007 show relatively low N2/He and N2/Ar ratios and high R/Ra values with respect to those measured in 2012. Such compositional and isotope variations were likely related to injection of mafic magma that likely triggered the 2000 eruption. Therefore, changes affecting the magmatic systemhad a delayed effect on the chemistry of the CCVC gases due to the presence of the hydrothermal reservoir. However, geochemical monitoring activities mainly focused on the behavior of inert gas compounds (N2 and He), should be increased to investigate the mechanism at the origin of the unrest started in 2011.
    Description: Published
    Description: 44–56
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: restricted
    Keywords: Fluid geochemistry ; Copahue volcano ; Fumarolic fluid ; Hydrothermal reservoir ; Volcanic unrest ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
    Publication Date: 2024-05-09
    Description: Measurements of soil fluxes of hydrothermal gases, with special emphasis on C6H6, as well as chemical composition of mono-aromatic compounds in fumaroles and air, were carried out in April 2012 at the Solfatara crater (Campi Flegrei, Southern Italy) to investigate the distribution and behavior of these species as they migrate through the soil from their deep source to the atmosphere. Soil fluxes of CO2, CH4 and C6H6 exhibit good spatial correlation, suggesting that diffuse degassing is mainly controlled by local fractures. The calculated total output of diffuse C6H6 from Solfatara is 0.10 kg day 1, whereas fluxes of CO2 and CH4 are 79 103 and 1.04 kg day 1, respectively. A comparison between soil gas fluxes and fumarole composition reveals that within the crater soil CH4 is significantly affected by oxidation processes, which are more efficient for low gas fluxes, being dependent on the residence time of the uprising hydrothermal gases at shallow depth. Benzene degradation, mainly proceeding through oxidation via benzoate, seems to be strongly controlled by the presence of a shallow SO2 4 -rich aquifer located in the central and southwestern sectors of the crater, suggesting that the process is particularly efficient when SO2 4 acts as terminal electron acceptor (SO4 reduction). Relatively high C6H6/C7H8 ratios, typical of hydrothermal fluids, were measured in air close to the main fumarolic field of Solfatara crater. Here, C6H6 concentrations, whose detection limit is 0.1 lgm 3, are more than one order of magnitude higher than the limit value for ambient air (5 lgm 3). This suggests that hydrothermal fluids have a strong impact on air quality in the immediate surroundings of the fumarolic vents. Significant concentrations of endogenous mono-aromatics were also detected in air samples collected from the northern and western sides of the crater, where these gas compounds are mostly fed by diffuse degassing through the crater bottom soil.
    Description: Published
    Description: 142–153
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: restricted
    Keywords: hydrothermal gases ; Solfatara crater ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
    Publication Date: 2013-04-18
    Description: Twenty-five lava fountains occurred on Mt. Etna from January 2011 to April 2012. In summer 2012 volcanic activity resumed in a milder form within the Bocca Nuova crater, before it came to an essential halt in August 2012. All these unrests offer rich material for testing automatic procedures of data processing and alert systems, running 24/7, in the context of volcano surveillance. We focus on the seismic background radiation – volcanic tremor – which plays a key role in the monitoring of Mt. Etna. Since 2006 a multistation alert system has been established in the INGV operative centre of Catania exploiting STA/LTA ratios. Besides, also the spectral characteristics of the signal, which change correspondingly to the type of volcanic activity, can be exploited for warning purposes. Here we apply Self Organizing Maps and Fuzzy Clustering which offer an efficient way to visualize signal characteristics and its development with time. All these techniques allow to identify early stages of eruptive events, and automatically flag a critical status before this becomes evident in conventional monitoring techniques. Changes of tremor characteristics are related to the position of the source of the signal. The location of the sources exploits the distribution of the amplitudes across the seismic network. The locations were extremely useful for warning, throughout both the flank eruption in 2008 as well as the 2011 lava fountains, during which a clear migration of tremor sources towards the eruptive centres could be noticed in advance. The location of the sources completes the picture of an imminent volcanic unrest, and corroborates early warnings flagged by the changes of signal characteristics. Real time data processing requires computational efficiency, robustness of the methods and stability of data acquisition. The amplitude based multi-station approach is not sensitive to the failure of single stations and therefore offers a good stability. The single station approach, exploiting unsupervised classification techniques, limits logistic efforts, as only one or few key stations are necessary. Both strategies have proven to be insensitive to disturbances (undesired transients like earthquakes, noise, short gaps in the continuous data flow). False alarms were not encountered so far. Stable data acquisition and processing come with a properly designed data storage solution. The reliability of data storage and its access is a critical issue. A cluster architecture has been realized for failover protection, including a Storage Area Network system, which allow easy data access following predefined user policies. We present concepts of the software architectures deployed at INGV Osservatorio Etneo in order to implement this tremor-based multi approach system. We envisage the integration of seismic data and those originating from other scientific fields (e. g., volcano imagery, geochemistry, deformation, gravity, magneto-telluric). This will facilitate cross-checking of evidences encountered from the single data streams, in particular allow their immediate verification with respect to ground truth.
    Description: Published
    Description: Nicolosi (Catania, Italy)
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 5.6. TTC - Attività di Sala Operativa
    Description: open
    Keywords: Etna, Volcanic tremor ; Volcano monitoring, Pattern recognition ; Self Organizing Map, Fuzzy clustering ; Data acquisition ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.01. Computational geophysics::05.01.01. Data processing ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Oral presentation
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  • 9
    Publication Date: 2017-04-04
    Description: Herein we report on the chemical and isotopic (C, H, O, and He) compositions of the fluids from La Fossa crater fumaroles of Vulcano from 1999 to 2010. Consistent with records obtained since the end of the 1980s, our data show that the geochemical features of the fumarole system have experienced several episodes of remarkable change, each lasting no more than a few months. Typical signatures of these short-term anomalies are large increments in CO2, N2, and He concentrations, coupled to increased 13C/12C isotopic ratios, but their meaning remains widely debated. Within a model of fumarolic fluids based on mixing between hydrothermal and magmatic endmembers, we have developed a novel approach to constrain chemical (He/ CO2 and N2/He) and isotopic (13C/12C, D/H, and 3He/4He) ratios of the magmatic endmember during the short-term anomalies. Although much of the geochemical variability in fumaroles results from changes in mixing proportions, the magmatic fluid unquestionably shows significant variations in time. The magmatic He/CO2, N2/He, 13C/12C, and 3He/4He values throughout 1988–1996 differed from those feeding the anomaly at the end of 2004. Early clues of the new magmatic fluid appeared in 1998–1999, far from any short-term anomaly, whereas new and old magmatic fluids coexisted after 2004. We quantitatively prove that the detected geochemical changes are consistent with the degassing path of a magma having a latitic composition, and suggest the presence of two magma ponding levels at slightly different pressures, where bubble–melt decoupling can occur. The different He-isotope compositions at these levels suggest low hydraulic connectivity typical of a complex reservoir with dike and sill structures. In this framework, the short-term geochemical anomalies are probably due to gas accumulation at the top of magma bodies followed by massive escape, or activation of new degassing levels in the reservoir, for which the stress field almost certainly plays a key role. Such a scenario explains the observed increases in both fumarole output and shallow high-frequency seismicity (due to increased pore pressure) during the anomalies, while being consistent with the concomitant absence of any deep seismicity or ground deformation, eventually related to magma movement.
    Description: Published
    Description: 158-178
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: restricted
    Keywords: fumarole geochemistry ; magma degassing ; thermodynamic modeling ; noble gas geochemistry ; carbon isotopes ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 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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  • 10
    Publication Date: 2017-04-04
    Description: Herein, we present a method for continuous measurement of soil CO2 flux that is completely new and distinct from existing instruments. The foremost difference is that instead of using an infrared gas analyser (IRGA), the new device measures soil CO2 flux by means of a simple pressure sensor, measuring pressure transients inside a closed polymeric tube inserted into the soil. This allows continuous measurements even in soil placed in environments that could potentially damage IRGA. In addition, due to the innovative operating principle, measurements of soil CO2 flux can be effortlessly performed also in strongly harsh weather conditions. Theoretical equations were derived for calculating soil CO2 flux solely using measured transient values. The reliability of the equations was rigorously tested with a variety of experiments. Continuous measurements over four months, acquired in a high-emission area on the Island of Vulcano, compared favourably with the data obtained using an established method.
    Description: Published
    Description: 102-109
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: restricted
    Keywords: Soil CO2 flux measurements ; Continuous monitoring ; Methods of measurement ; Polymeric membranes ; 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 ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 11
    Publication Date: 2017-04-04
    Description: Our study is aimed to develop a 3D physical model of the Campi Flegrei geothermal system, in order to achieve a more accurate and comprehensive representation of the hydrothermal processes occurring in the caldera. The new model, developed by using the TOUGH2 code simulator, accounts for the caldera rocks' physical properties, bathymetry and water table topography. In particular, the computational domain is constrained by density values obtained by tomographic inversion of gravity data collected during several surveys at CF both onshore and offshore the caldera. Empirical relations between density and porosity and between porosity and permeability, derived by published data on samples cored in deep wells or collected in outcrops, allowed us to characterize the main rocks physical parameters controlling the dynamic of the CF geothermal system. We have performed and compared several simulations investigating the effects of the injection at depth, underneath Solfatara crater, of a hot gaseous mixture rich in CO2. We show that, with respect to the available literature on 2D axisymmetric models, the effects of the water table topography together with the bathymetry and the heterogeneous distribution of the rocks' physical properties, lead to important differences in the hydrothermal circulation of fluids at CF. These constraints allow the activation of convective cells with different behaviors, which produce variable patterns of temperature inside the hydrothermal system. As a consequence, the predominant effect is again represented by a central plume below the Solfatara crater, but with a non-axisymmetric structure and a wider extension. Additionally, high temperature zones are present near the coastline and in the middle part of the submerged area of the caldera with a SE–NW alignment. Moreover, our results indicate that, the submerged part of the CF caldera would deserve a more accurate study and survey, being affected by phenomenon of heating and degassing. This information could be very useful in terms of hazard assessment and volcanic risk mitigation in such an active and densely inhabited volcanic and geothermal area.
    Description: Published
    Description: 172-182
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: restricted
    Keywords: Campi Flegrei ; Geothermal system ; 3D model ; Water table topography ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
    Publication Date: 2017-04-04
    Description: Epidermis micromorphology of in situ Erica arborea L. exposed for generations to long-term effect of volcanic gases in Pisciarelli and Solfatara di Pozzuoli areas have been studied by X-ray analyses, SEM and TEM observations. In particular, the aim of this study is to investigate the effects of volcanic gases on extant and possibly fossil plants. Plants of the same species living in a nearby control site were also studied for comparison. SEM coupled with EDX analysis was used to localize different elements within the leaves (mesophyll, cell wall and cuticle). After conventional and cryo preparation, SEM of mature leaves ascertained that the abaxial side is more serrate in fumigated leaves and hairs, epicuticular wax alterations have also been noted. Leaves experiencing chronic fumigation display stomata more sunken with respect to the epidermal surface. TEM of transverse and longitudinal sections of cuticle showed an outer A2 granular amorphous layer and external to a B1 fibrillous layer. Significant statistical variations of ultrastructural components of the cuticle revealed a response of E. arborea to this extreme environment. At the ultrastructural level, significant variations in thickness of the cell wall plus cuticle, cell wall and A2 layer among fumigated and non-fumigated leaves have been found. In the studied localities a positive correlation between atmospheric CO2 concentration and the thickness of A2 layer also exists. The results are of interest being applicable in the understanding of plant cuticle responses during periods of normal vs. volcanic activity.
    Description: Published
    Description: 197– 206
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: restricted
    Keywords: Phlegrean Fields ; Erica arborea ; Volcanic gases ; Epidermis ; Cuticle ultrastructure ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 03. Hydrosphere::03.04. Chemical and biological::03.04.04. Ecosystems ; 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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  • 13
    Publication Date: 2017-04-04
    Description: We present the first chlorine isotope compositional data for gases and lavas from Mount Etna (Italy), and to our knowledge, of active Mediterranean volcanism. We investigated lavas erupted and gases discharged during 2008-2011 from a high-temperature fumarole (HT; 〉300°C) and plume gases from both North East and Central Craters. Most of the samples vary in a narrow range of chlorine isotope composition (37Cl values ≈ 0 ± 0.7‰) with gases partially overlapping with rocks. Only HT gases sampled in 2009 have been clearly affected by secondary processes (37Cl values 〉 15.9‰), resulting in partial removal of chlorine and isotopic fractionation producing a 37Cl enrichment in the residual gaseous HCl. These secondary processes also affect, although to a lesser extent, plume gases from North East Crater (NEC). Although post-magmatic processes are able to modify the chlorine isotope composition, 37Cl values are not affected by magma degassing for residual fractions ≥ 0.3 in the melt, or any effect is within our data variability. Finally, 37Cl values and Cl/K ratios of magmatic chlorine constrain the Etnean source to be compatible with depleted mantle (DMM) contaminated by altered oceanic crust (AOC), in agreement with indications from more common isotopic tracers of mantle processes.
    Description: Published
    Description: 134-142
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: restricted
    Keywords: Mount Etna ; chlorine isotope ; plume ; fumarole ; degassing ; mantle source ; 04. Solid Earth::04.04. Geology::04.04.07. Rock geochemistry ; 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::04.08.05. Volcanic rocks
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 14
    Publication Date: 2017-04-04
    Description: Passive samplers were used to measure the atmospheric concentrations of SO2 naturally emitted at three volcanoes in Italy (Etna, Vulcano and Stromboli) and of H2S naturally emitted at three volcanic/geothermal areas in Greece (Milos, Santorini and Nisyros). The measured concentrations and dispersion patterns varied with the strength of the source (open conduits or fumaroles), the meteorological conditions and the area topography. At Etna, Vulcano and Stromboli, SO2 concentrations reach values that are dangerous to people affected by bronchial asthma or lung diseases (〉1000 μg m−3). H2S values measured at Nisyros also exceed the limit considered safe for the same group of people (〉3000 μg m−3). The data obtained using passive samplers represent time-averaged values over periods from a few days up to 1 month, and hence concentrations probably reached much higher peak values that were potentially also dangerous to healthy people. The present study provides evidence of a peculiar volcanic risk associated with tourist exploitation of active volcanic areas. This risk is particularly high at Mt. Etna, where the elderly and people in less-than-perfect health can easily reach areas with dangerous SO2 concentrations via a cableway and off-road vehicles
    Description: Published
    Description: 1-13
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: restricted
    Keywords: Sulphur dioxide ; Hydrogen sulphide ; Volcanic risks ; Gas hazard ; 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 ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 15
    Publication Date: 2017-04-04
    Description: Commenton “CO2 variabilityinmid-oceanridge basalts fromsyn-emplacementdegassing: Constraintsoneruptiondynamics”
    Description: Published
    Description: 251-253
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: restricted
    Keywords: non-equilibrium degassing, modeling, CO2, bubble growth, MORB, gas geochemistry ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics
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  • 16
    Publication Date: 2020-12-15
    Description: The source properties of the Long-Period events that occurred at Campi Flegrei Caldera (Italy) during the 2004–2006 ground uplift episode are investigated by analyzing the temporal release of seismic energy, amplitude distribution and inter-event occurrence time. Moreover, an entropy-based decomposition method is applied to identify the simpler waveforms thought to be representative of the source mechanism of Long-Period events. On the basis of the outcomes, we propose that the main part of these events is the result of a source process triggered by a mechanism of fluid charge/discharge, which causes pressure drop in a main branch of a dentritic network of the hydrothermal system. In this model, the rate of the Poissonian process (about 15 min), which drives the occurrence of the Long-Period events, provides the average recharge time of the system up to the critical condition. A partial shunting of the fluid flow away from the main conduit activates the ”resonance” of a second branch, spatially separated from the first one. This is a process that occurs whenever the fluid pressure exceeds a critical value and produces less energetic Long-Period events. The mechanism of pressure variation in the two conduits generates signals with preferred amplitude scales, described by a bi-lognormal distribution. From a dynamical point of view, Long-Period events result well described by a low-dimensional dynamical system. Finally, the time pattern of the energy release and its correlation with the diurnal solid earth tide suggest that the whole mechanism of fluid charge/discharge is likely modulated by tidal stress variation.
    Description: Published
    Description: 16-30
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: partially_open
    Keywords: Lp sources ; Poissonian occurrence ; Tidal modulation ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 17
    Publication Date: 2012-02-03
    Description: The 2001 Etna eruption occurred from July 17th to August 9th, 2001 and was preceded by several days of intense seismicity and ground deformation. We investigated the seismic activity recorded during November 2000 - June 2001 interval time preceding the eruption, to understand the meaning of the seismicity connected to the dike intrusion, that locally modified the stress field acting in the area. The earthquakes were recorded by the permanent local networks operating during that time and run by the Istituto Internazionale di Vulcanologia (IIV-CNR) and the Sistema POSEIDON. During the analyzed period, 683 earthquakes have been firstly localized by means of a 1D velocity model derived from Hirn et al., 1991 using the software HypoEllipse [Lahr, U. S. Geol. Survey, Open-File Report, 89/116, 81 pp., 1989]. In order to further improve the quality of the seismic dataset, we extracted 522 earthquakes with Gap less than 200°, Erh 〈 1.5 km, Erz 〈 2 km, RMS less than 0.5 sec, and a minimum number of S phases equal to 2. This latter seismic dataset was relocated using TomoDD code [Zhang and Thurber, BSSA, 93, 1875-1889. 2003] and a 3D velocity model [Patanè et al., Science, 313, 821- 823, 2006 after modified]. Using first motion polarity data, 3D fault plane solutions were computed by means of the software FPFIT [Reasenberg and Oppenheimer, U.S. Geological Survey Open File Report, 85/739, 109 pp, 1985]. Then, adopting restricted selection criteria (Npol more than 12; focal plane uncertainties less than 20°; number of solutions 〈 2; number of discrepancies less than 15%), we selected 116 FPSs. This dataset represented the input file for the stress and strain tensors computation using the inversion codes developed by Gephart and Forsyth,[ JGR 89: 9305-9320, 1984] and by Kostrov [Izv Acad Sci USSR Phys Solid Earth, 1, 23-40], respectively. On the basis of P and T axes distribution and the orientation of the main seismogenic stress and strain axes, we put some seismological constraints on the recharging phase leading to the 2001 Etna eruption.
    Description: Published
    Description: Salina
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: open
    Keywords: Etna ; stress ; strain ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 18
    Publication Date: 2017-04-04
    Description: We present the first application of a time reverse location method in a volcanic setting, for a family of long-period (LP) events recorded on Mt Etna. Results are compared with locations determined using a full moment tensor grid search inversion and cross-correlation method. From 2008 June 18 to July 3, 50 broad-band seismic stations were deployed on Mt Etna, Italy, in close proximity to the summit. Two families of LP events were detected with dominant spectral peaks around 0.9 Hz. The large number of stations close to the summit allowed us to locate all events in both families using a time reversal location method. The method involves taking the seismic signal, reversing it in time, and using it as a seismic source in a numerical seismic wave simulator where the reversed signals propagate through the numerical model, interfere constructively and destructively, and focus on the original source location. The source location is the computational cell with the largest displacement magnitude at the time of maximum energy current density inside the grid. Before we located the two LP families we first applied the method to two synthetic data sets and found a good fit between the time reverse location and true synthetic location for a known velocity model. The time reverse location results of the two families show a shallow seismic region close to the summit in agreement with the locations using a moment tensor full waveform inversion method and a cross-correlation location method.
    Description: Published
    Description: 452-462
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Volcano seismology ; Computational seismology ; Wave propagation ; 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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  • 19
    Publication Date: 2017-04-04
    Description: (extended abstract)
    Description: INGV, Regione Sicilia, Ministero Sviluppo Economico
    Description: Published
    Description: Ettore Majorana Foundation and Centre for Scientific Culture, Erice, Sicily
    Description: open
    Keywords: Geodynamics ; Volcano-seismic correlation ; Seismic and volcanic risk ; Earth rotation and volcano-seismic events ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.03. Geodesy::04.03.02. Earth rotation ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Extended abstract
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  • 20
    Publication Date: 2017-04-03
    Description: Fluorine adsorption experiments were performed on 28 samples of the first 5 cm of topsoil collected on the flanks of Mt. Etna. The soil samples were equilibrated with F-rich rainwater (3.25 mg/L) at a soil/water weight ratio of 1/25. Aliquots of the supernatant were collected after 1, 7, 72, 720 and 5640 h and analysed for F content. The soil samples could be subdivided into three groups based on their F-adsorption behaviours after 1 h and at the end of the experiment: (1) negative adsorption (F released from the soil to the solution) after 1 h and negative or moderately positive adsorption at the end, (2) from negative after 1 h to strongly positive adsorption at the end, and (3) always strong positive adsorption. The adsorption capacity of the soils was positively correlated with the soil pH, the contents of finer granulometric fractions (clay and silt) and the weathering stage (as quantified by the chemical alteration index). The most F adsorbing soils are found at the periphery of the volcano where aquifers are more vulnerable to contamination due to the shallower depth of the water table. This study further evidences the importance of the Etnean soils in protecting groundwater from an excessive magmatic F input.
    Description: Published
    Description: 1179–1188
    Description: 4.4. Scenari e mitigazione del rischio ambientale
    Description: JCR Journal
    Description: restricted
    Keywords: volcanic soils ; fluoride adsorption ; Mt. Etna ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 05. General::05.08. Risk::05.08.01. Environmental risk
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  • 21
    Publication Date: 2017-04-04
    Description: In this paper, we report four years of soil CO2 emission data measured monthly at 130 sites in two peripheral areas of Mt Etna Volcano that are well known for their high discharge rates of volcanic gas. We remove the influence of atmospheric parameters, and by means of statistical analyses, we (i) demonstrate that variations in CO2 emissions are due mainly to CO2 of a deep origin and (ii) quantify the total amounts of CO2 derived from a deep magma source. Periods of anomalous deep degassing are identified in both areas. A comparison of the timing of these anomalies and geophysical data indicates that the periods of anomalous degassing can be mostly ascribed to intrusions of fresh magma into the Etna plumbing system, which is in agreement with many previous works. Based on the existing literature, we formulate an interpretative framework of magma migration within the plumbing system, consistent with temporal trends in the observed anomalies. Finally, we reconstruct the processes of recent magma ascent at Mt Etna based on our interpretative framework, published geophysical data, and records of volcanic activity.
    Description: Published
    Description: 218-227
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Soil CO2 flux ; Mt Etna ; Volcanic activity ; Magma transfer ; 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
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  • 22
    Publication Date: 2017-04-04
    Description: From October 2008 to November 2009, soil CO2, radon and structural field surveys were performed on Mt. Etna, in order to acquire insights into active tectonic structures in a densely populated sector of the south-eastern flank of the volcano, which is involved in the flank dynamics, as highlighted by satellite data (InSAR). The studied area extends about 150 km2, in a sector of the volcano where InSAR results detected several lineaments that were not well-defined from previous geological surveys. In order to validate and better constrain these features with ground data evidences, soil CO2 and soil radon measurements were performed along transects roughly orthogonal to the newly detected faults, with measurement points spaced about 100 m. In each transect, the highest CO2 values were found very close to the lineaments evidenced by InSAR observations. Anomalous soil CO2 and radon values were also measured at old eruptive fractures. In some portions of the investigated area soil gas anomalies were rather broad over transects, probably suggesting a complex structural framework consisting of several parallel volcano-tectonic structures, instead of a single one. Soil gas measurements proved particularly useful in areas at higher altitude on Mt. Etna (i.e. above 900 m asl), where InSAR results are not very informative/ are fairly limited, and allowed recognizing the prolongation of some tectonic lineaments towards the summit of the volcano. At a lower altitude on the volcanic edifice, soil gas anomalies define the active structures indicated by InSAR results prominently, down to almost the coastline and through the northern periphery of the city of Catania. Coupling InSARwith soil gas prospectingmethods has thus proved to be a powerful tool in detecting hidden active structures that do not show significant field evidences.
    Description: This work was funded by the DPC-INGV project “Flank”
    Description: Published
    Description: 27-40
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: CO2 ; Radon ; InSAR ; Faults ; Etna ; Volcano-tectonics ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 23
    Publication Date: 2017-04-04
    Description: The ordinary, low intensity, activity of Stromboli volcano is sporadically interrupted by more energetic events termed, depending on their intensity, “major explosions” and “paroxysms”. These short-lived energetic episodes represent a potential risk to visitors to the highly accessible summit of Stromboli. Observations made at Stromboli over the last decade have shown that the composition of gas emitted from the summit craters may change prior to such explosions, allowing the possibility that such changes may be used to forecast these potentially dangerous events. In 2008 we installed a novel, remote-controlled, open-path FTIR scanning system called Cerberus at the summit of Stromboli, with the objective of measuring gas compositions from individual vents within the summit crater terrace of the volcano with high temporal resolution and for extended periods. In this work we report the first results from the Cerberus system, collected in August-September 2009, November 2009 and May-June 2010. We find significant, fairly consistent, intra-crater variability for CO2/SO2 and H2O/CO2 ratios, and relatively homogeneous SO2/HCl ratios. In general, the southwest crater is richest in CO2, and the northeast crater poorest, while the central crater is richest in H2O. It thus appears that during the measurement period the southwest crater had a somewhat more direct connection to a primary, deep degassing system; whilst the central and northeast craters reflect a slightly more secondary degassing nature, with a supplementary, shallow H2O source for the central crater, probably related to puffing activity. Such water-rich emissions from the central crater can account for the lower crystal content of its eruption products, and emphasise the role of continual magma supply to the shallowest levels of Stromboli's plumbing system. Our observations of heterogeneous crater gas emissions and high H2O/CO2 ratios do not agree with models of CO2-flushing, and we show that simple depressurisation during magma ascent to the surface is a more likely model for H2O loss at Stromboli. We highlight that alternative explanations other than CO2 flushing are required to explain distributions of H2O and CO2 amounts dissolved in melt inclusions. We detected fairly systematic increases in CO2/SO2 ratio some weeks prior to major explosions, and some evidence of a decrease in this ratio in the days immediately preceding the explosions, with periods of low, stable CO2/SO2 ratios between explosions otherwise. Our measurements, therefore, confirm the medium term (~ weeks) precursory increases previously observed with MultiGas instruments, and, in addition, reveal new, short-term precursory decreases in CO2/SO2 ratios. immediately prior to the major explosions. Such patterns, if shown to be systematic, may be of great utility for hazard management at Stromboli's summit. Our results suggest that intra-crater CO2/SO2 variability may produce short-term peaks and troughs in CO2/SO2 time series measured with in-situ MultiGas instruments, due simply to variations in wind direction.
    Description: Published
    Description: 66-76
    Description: JCR Journal
    Description: open
    Keywords: OP-FTIR scanning system ; Stromboli Volcano ; Explosive activity ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 24
    Publication Date: 2017-04-04
    Description: In this paper we investigate nature and properties of narrow-band, transient seismic signals observed by a temporary array deployed in the Val Tiberina area (central Apennines, Italy). These signals are characterized by spindle-shaped, harmonic waveforms with no clear S-wave arrivals. The first portion of the seismograms exhibits a main frequency peak centred at 4.5 Hz, while the spectrum of the slowly decaying coda is peaked at about 2 Hz. Events discrimination is performed using a matched-filtering technique, resulting in a set of 2466 detections spanning the 2010 January–March time interval. From a plane-wave-fitting procedure, we estimate the kinematic properties of signals pertaining to a cluster of similar events. The repetition of measurements over a large number of precisely aligned seismograms allows for obtaining a robust statistics of horizontal slownesses and propagation azimuths associated with the early portion of the waveforms. The P-wave arrival exhibits horizontal slownesses around 0.1 s km−1, thus suggesting waves impinging at the array almost vertically. Separately, we use traveltimes measured at a sparse network to derive independent constraints on epicentral location. Ray parameters and azimuths are calibrated using slowness measurements from a local, well-located earthquake. After this correction, the joint solution from traveltime inversion and array analysis indicates a source region spanning the 1–3 km depth interval. Considerations related to the source depth and energy, and the occurrence rate which is not related to the daily and weekly working cycles, play against a surface, artificial source. Instead, the close resemblance of these signals to those commonly observed in volcanic environments suggest a source mechanism related to the resonance of a fluid–filled fracture, likely associated with instabilities in the flux of pressurized CO2.
    Description: Published
    Description: 918-928
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: reserved
    Keywords: Fracture and flow ; Earthquake source observations ; Interface waves ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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  • 25
    Publication Date: 2017-04-04
    Description: Ambrym is one of the most actively erupting basaltic volcanoes in the Vanuatu island arc. Scoria clasts collected from a fallout deposit in the inner terrace of its Benbow active crater were analyzed through series of synchrotron X-ray computed microtomographic experiments, as well as permeability measurements and simulations. Our goal was to reconstruct and visualize scoria textures in 3D and to quantify vesicularity, permeability, vesicle sizes and distributions in order to understand how gas moves in and out of Ambrym basaltic magma. We find that vesicle size distributions in the volume range between ~ 103 and 1010 μm3 define two scoria classes. Vesicle size distributions in the low-to-moderately (0.44–0.67) vesicular samples can be fit by power laws with an exponent of 1 ± 0.2; distributions in the highly vesicular (0.86–0.88) samples can be fit by power laws with a higher exponent (1.4 to 1.7), as well as by exponential fits. Highly vesicular samples exhibit a very pronounced large vesicle, consisting of networks of smaller, interconnected vesicles, that is more than three orders of magnitude larger in volume than all other vesicles in each distribution. This type of vesicle is not found in the low-to-moderately vesicular samples. In addition, vesicle number density negatively correlates with vesicularity: less vesicular samples have the highest number density and vice versa, and contain far more numerous small-to-medium-sized vesicles than highly vesicular samples. Measured and calculated viscous (Darcian) permeabilities overlap in the range 10− 13 and 10− 9 m2, with higher values in the more vesicular samples. We ascribe these differences in the textural and physical properties of the scoria clasts to their derivation from distinct magma portions in the conduit that were driven by convective overturn and underwent different vesiculation histories and gas transport dynamics. Comparing basaltic scoria clasts from Ambrym to those from mild explosive activity at Stromboli volcano (Italy) reveals that differences in their vesicle size distributions may result from the influence of different crystal contents and shapes on the vesiculation and permeability of the respective magmas. Finally, we highlight how rheological properties have a fundamental role in determining the degassing behaviour of basaltic magma at Ambrym and other volcanoes in general.
    Description: Published
    Description: 55-64
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: restricted
    Keywords: Ambrym ; Basaltic scoria ; 3D X-ray micro-tomography analysis ; Volcanic degassing ; Magma convection ; Crystal effect ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
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  • 26
    Publication Date: 2017-04-04
    Description: Volcanic emissions are considered one of the major natural sources of several trace metals (e.g. As, Cd, Cu, Pb, and Zn) to the atmosphere [Nriagu, 1989], and the geochemical cycles of these elements have to be considered strongly influenced by volcanic input. However, the accurate estimation of the global volcanic emissions of volatile trace metals into the atmosphere is still affected by a high level of uncertainty. The latter depends on the large variability in the emission of the different volcanoes, and on their changing stage of activity. Moreover, only few of the potential sources in the world have been directly measured [Hinkley et al. 1999]. Atmospheric deposition processes (wet and dry) are the pathways through which volcanic emissions return to the ground (soils, plants, aquifers), resulting in both harmful and beneficial effects [Baxter et al. 1982; Aiuppa et al. 2000; Brusca et al. 2001; Delmelle, 2003; Bellomo et al. 2007; Martin et al. 2009; Floor et al. 2011; Calabrese et al. 2011]. In the first part of this study we present the results of a literature review on trace metals emissions from active volcanoes around the world. In the second part, we present new data on the fluxes of the trace metals from Etna (Italy) and four active volcanoes in the world: Turrialba (Costarica), Nyiragongo (DRC), Mutnovsky and Gorely (Kamchatka). We found 27 publications (the first dating back to the 70’s), 13 of which relate to the Etna and the other include some of the world’s most active volcanoes: Mt. St. Helens, Erebus, Merapi, White Island, Kilauea, Popocatepetl, Galeras, Indonesian arc, Satasuma and Masaya. The review shows that currently there are very few data available, and that the most studied volcano is Mt. Etna. Using these data, we defined a range of fluxes for As, Ba, Bi, Cd, Cu, Fe, Mn, Pb, Se, V and Zn (Figure 1). To obtain new data we sampled particulate filters at the five above mentioned volcanoes. Filters were mineralized (acid digestion) and analyzed by ICP-MS. Sulphur to trace element ratios were related to sulphur fluxes to indirectly estimate trace elements fluxes. Etna confirms to be one of the greatest point sources in the world. The Nyiragongo results to be also a significant source of metals to the atmosphere, especially considering its persistent state of degassing from the lava lake. Also Turrialba and Gorely have high emission rates of trace metals considering the global range. Only Mutnovsky Volcano show values which are sometimes lower than the range obtained from the review, consistent with the fact that it is mainly a fumarolic field. This work highlights the need to expand the current dataset including many other active volcanoes for a better constraint of global trace metal fluxes from active volcanoes.
    Description: Published
    Description: Nicolosi (Catania)
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: open
    Keywords: Volcanic degassing ; trace elements ; environmental impact of volcanic activity ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 27
    Publication Date: 2017-04-04
    Description: Volcanic emissions represent one of the most relevant natural sources of trace elements to the troposphere, both during and between eruptions. Due to their potential toxicity they may have important environmental impacts from the local to the global scale. Mount Etna, the largest European volcano and one of the most active volcano in the world, covers an area of about 1250 km2 and reaches an altitude of about 3340 m. It has been persistently active during historical time, with frequent paroxysmal episodes separated by passive degassing periods. Atmospheric precipitation was collected approximately every two weeks, from April 2006 to December 2007, using a network of five rain gauges, located at various altitudes on the upper flanks around the summit craters of Etna Volcano. The collected samples were analysed for major (Ca, Mg, K, Na, F, SO4, Cl, NO3) and a large suite of trace elements (Ag, Al, As, Au, B, Ba, Be, Bi, Cd, Co, Cr, Cs, Cu, Fe, Hg, La, Li, Mn, Mo, Ni, Pb, Rb, Si, Sb, Sc, Se, Sr, Th, Ti, Tl, U, V, Zn) by using different techniques (IC, SPEC, ICP-MS and CV-AFS). The monitoring of atmospheric deposition gave the opportunity to occasionally sample volcanic fresh ashes emitted by the volcano during the paroxysmal events. This was possible because the network of five rain gauges were equipped with a filter-system to block the coarse material. In this way, more than twenty events of ashfall were collected. Unfortunately, only half of these samples were suitable for a complete chemical analysis, because of the small amount of sample. In order to obtain elemental chemical composition of ashes, powdered samples were analysed by a combination of methods, including X-ray Fluorescence Spectroscopy (XRF), total digestion followed by Inductively Coupled Plasma Emission Mass Spectrometry (ICP-MS), Instrumental Neutron Activation Analysis (INAA), and infrared detection (IR). The chemistry of rainwater reveals that most of the investigated elements have higher concentrations close to the emission vent of the volcano, confirming the prevailing volcanic contribution. Rainwater composition clearly reflects the volcanic plume input. Ash-normalised rainwater composition indicates a contrasting behaviour between volatile elements, which are highly-enriched in rainwater, and refractory elements, which have low rainwater/ash concentration ratios. The degree of interaction between collected ash and rainwater was variable, depending on several factors: (i) the length of the period in which tephra was present in the sampler (the ash fall may have occurred any day from the first to the last day of the rain collecting period); (ii) the amount of rainwater fallen on the collectors after the ash-fall event, and its acidity; (iii) the granulometry of the ash samples that was widely variable (from few centimetres to micrometric particles) increasing the interaction with decreasing dimensions of the grains; (iv) the distance of collector with respect to the craters. In order to investigate the role of volcanic ash on the evolution of the rainwater chemistry, absolute concentrations of rain and ash were plotted in binary plot diagrams (Figure 1). Each diagram corresponds to a single event, and pH and TDS of the solution collected is reported. The diagonal bars in the diagrams represent the rain/ash ratios (1:1 and 1:10000). The results confirm that sulphate and halide salt aerosols are adsorbed onto ash particles, and their rate of dissolution in rainwater depends on solubility. Moreover, rapid chemical weathering of the silicate glass by volcanic acid (SO2, HCl and HF) can also explain the enrichment of several refractory elements (Na, K, Ca, Mg, Si, Al, Fe, Ti, Sc). Our observations highlight how explosive activity can increase enormously the deposition rate of several chemical elements, up to several km away from the emission vents.
    Description: Published
    Description: Nicolosi (Catania)
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: open
    Keywords: volcanic ash ; trace elements ; environmental impact of volcanic activity ; rainwater chemistry ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Extended abstract
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  • 28
    Publication Date: 2017-04-04
    Description: In this paper the history of the Mobile Seismic Network of the Osservatorio Vesuviano (at present Department of Napoli of the Istituto Nazionale di Geofisica e Vulcanologia – INGV) is described. The instrumental development and the main research and monitoring activities since the early 1980’ are reported. Starting from the analog stations with magnetic tape recording to the first digital stations with trigger recording, until the modern multichannel 24bit devices, the technological development of the last 30 years has given a strong contribution to increase the knowledge in the seismology and seismotectonics fields. The Mobile Seismic Network has been engaged in active and passive seismic studies both on volcanic and tectonic areas. Particularly, the contribution of the Mobile Seismic Network for the monitoring of Neapolitan active volcanoes has been very important to improve the Permanent Network. During seismic crises high quality data have been gathered allowing detailed analyses of the seismic activity. Moreover, the time synchronization by means of GPS time code allowed the deployment of the Mobile Network abroad and the collaboration with the main international research institutes. At present, the Mobile Seismic Network of the Osservatorio Vesuviano is developing on multichannel acquisition systems, also in array configuration, to gathered simultaneously seismic signals with a large frequency band.
    Description: Published
    Description: 1-51
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 3.2. Tettonica attiva
    Description: N/A or not JCR
    Description: open
    Keywords: mobile network ; Vesuvius ; Campi Flegrei ; data acquisition ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 29
    Publication Date: 2017-04-04
    Description: At Stromboli volcano, Italy, continuous seismic monitoring and periodic, visual observations of volcanic activity for surveillance purposes began in the mid-1980s. Since 1985, two eruptions have occurred, one lasting from December, 1985 until April, 1986, and one in May, 1993. There have also been two small overflows, in 1990 and 1994. Since these episodes of lava effusion, the persistent Strombolian activity of the volcano has had several fluctuations during the past 15 years. Some episodes climaxed in powerful explosions. According to seismic records, these paroxysms consisted of a variable number of explosion quakes in rapid succession (i.e. from tens of seconds to a few minutes), associated with a notable increment in the amplitude of volcanic tremor. Throughout these episodes - which are called explosive sequences - lapilli, fragments of old rock, and bombs of varying dimensions were ejected, affecting an area greater than the crater terrace where the active craters are located. In this article, we describe the explosive sequences recorded at Stromboli between 1985 and 1999. We provide a characterization in terms of reduced displacement and duration for nine episodes occurring in 1998 and 1999. Their reduced displacements range from 15 to 124 cm2; their durations are between 6 and 18 min. We find no change in the frequency content of the seismic signal several minutes before and during the sequences. Considering medium- to long-term behavior, the spectral amplitude of the seismic signal decreases or has low values over several months preceding the occurrence of the paroxysms. This feature is common to 20 of the 22 explosive sequences, and is indicative of internal conditions that periodically characterize the feeder. We surmise that the paroxysms are the result of the partial obstruction of the volcanic conduit when the magma column is low or dropping. The onset of the explosive sequence, causing the sudden removal of the material which forms the obstruction, would trigger a sudden depressurization of the conduit and the rapid rise of magma from depth.
    Description: Published
    Description: 137-150
    Description: JCR Journal
    Description: reserved
    Keywords: Stromboli ; Paroxysms ; Seismicity ; Volcanoes ; 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)
    Type: article
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  • 30
    Publication Date: 2017-04-04
    Description: Crustal tectonic seismicity in the Southern Tyrrhenian Sea is characterized by the high occurrence rates of earthquakes to the west of the alignment of Salina, Lipari and Vulcano islands in the Aeolian archipelago. Only a few earthquakes affect the crustal region east of these islands, whereas intermediate and deep seismicity plays a relevant role. Based on this evidence, two aspects of the seismic swarm recorded at the Aeolian Island Seismic Network between June 6 and 17, 1999 looked anomalous. The first aspect concerned the number of earthquakes (78) that affected the Stromboli submarine edifice in a short time interval. Secondly, despite the low maximum magnitude Md 3.2 reached, the cumulative strain release was conspicuous in comparison with previous swarms in this region. We localized the swarm about 6 km northeast of Stromboli, at a depth between 8 and 12km. The source region was identified using standard methods of hypocentral location, as well as azimuth analysis. It is worth noting that the volcanic activity at Stromboli did not change significantly during the swarm nor throughout the following months. Therefore, the seismic swarm had no link with volcanic activity observed at the surface. Most of the earthquakes shared similar waveform and frequency content, and can be divided into families. We identified some earthquakes - with magnitude up to Md 3 - having relatively low frequency content at different seismic stations. This anomalous feature leads us to hypothesize the presence of fluid circulation and/or propagation of seismic waves in a ductile medium. Our hypothesis is in agreement with studies on marine geology, which highlight various forms of submarine volcanism in the southern basin of the Tyrrhenian Sea.
    Description: This work was financially supported by the EC project MULTIMO (Contract No. EVG1-CT-2000-00021).
    Description: Published
    Description: 121-136
    Description: JCR Journal
    Description: reserved
    Keywords: Earthquakes ; Seismic swarm ; Volcanoes ; Stromboli ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 31
    Publication Date: 2017-04-04
    Description: A 4-year geochemical survey of some fumaroles at the Voragine summit crater of Mt Etna was performed in combination with synchronous monitoring of peripheral gas emissions at the base of the volcano. This was the first geochemical study at Mt Etna to have included the abundances of Ar, He, and C isotopes. Once the effects of postmagmatic shallow processes were identified and quantitatively removed, the He–Ar–CO2 systematics of the Voragine crater fumaroles and peripheral gas emissions described the same degassing path. Combining the carbon-isotope composition with information about noble gases provided evidence that the crater fumaroles are fed from a two-endmember mixture composed of a deep member coming from pressures between 200 and 400 MPa (depending on time), and a shallower one exsolved at 130 MPa. Similar mixing processes probably also occur in gases from peripheral vents. The simultaneous assessment of d13CCO2 and He/Ar values of crater fumaroles over time has identified simple changes in the mixing proportion between the two endmembers and, moreover, periods during which the exsolution pressure of the deep fluid increased. These periods seem to be linked to pre-eruptive phases of the volcano. The identified open-system degassing processes are indicative of efficient bubble–melt decoupling at depth, whereas the mixing process requires a convective transfer of the deeply exsolved fluids toward shallower levels of magma where further vapor is exsolved. In agreement with the most recent geophysical and petrological data from Mt Etna, these observations allow inferences about a deep portion of the plumbing system (5 to 12 km b.s.l.), comprising sill-like reservoirs connected by small vertical structures, and a main reservoir at 2–3 km b.s.l. that is probably fluxed by magmatic volatiles. 2012 Elsevier Ltd. All rights reserved.
    Description: Published
    Description: 380-394
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: restricted
    Keywords: gas geochemistry, isotopes, degassing, modelling ; 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::04.08.03. Magmas ; 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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  • 32
    Publication Date: 2017-04-04
    Description: We analyzed crater SO2 fluxes from Mt Etna, together with soil CO2 effluxes from the volcano's flanks, in the period from 2001 to 2005. Between the 2001 and 2002–2003 eruptions, persistently low values of both parameters suggest that no new gas-rich magma was accumulating at shallow depth (b5 km) within Etna's central conduit, whereas very high SO2 sin-eruptive fluxes during the two eruptions indicated sudden decompression of an un-degassed magma rising along newly-formed eccentric conduits. In November 2003, soil CO2 data indicate migration of gas-rich magma from deep (〉10 km) to shallow (b5 km) portions of the feeding conduits, preceded by an increase in crater SO2 fluxes. A similar behavior was observed also during and after the following 2004–2005 eruption. This degassing style matches a period of increased structural instability of the volcanic edifice caused by acceleration of spreading that affected both its eastern and southern flanks. Spreading could have triggered progressively deeper depressurization in the central conduit, inducing release of the more soluble gas (SO2) first, and then of CO2, contrary to what was observed before the 2001 eruption. This suggests that the edifice has depressurized, promoting ascent of fresh-magma and increasing permeability favouring release of CO2 flux. By integrating geochemical and structural data, previous degassing models developed at Mt. Etna have been updated to advance the understanding of eruptive events that occurred in recent years.
    Description: This work was funded by grants from the Istituto Nazionale di Geofisica e Vulcanologia (INGV) and from the Dipartimento per la Protezione Civile (Italy).
    Description: Published
    Description: 90-97
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: reserved
    Keywords: Geochemical modeling ; volcano monitoring ; volcanic gases ; Tectonics and magmatism ; flank collapse ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 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::04.07.02. Geodynamics ; 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::04.08.01. Gases ; 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::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.08. Risk::05.08.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 33
    Publication Date: 2017-04-04
    Description: Cuticle micromorphology together with epidermal and epistomatal wax, in both current- and first-year-old needles of conifer Pinus halepensis (Aleppo pine) trees growing under volcanic gas fumigation was analysed in Pisciarelli area, Campi Flegrei, Southern Italy. As a control, current- and first-year-old needles growing far from volcanic gas emission were also sampled. Using a multidisciplinary approach with SEM, TEM and X-ray, volcanic gases were shown to cause degradation on epicuticular and epistomatal waxes. Significant statistical variations of ultrastructural components of the cuticle, with 30 measurements, including total thickness of the cuticle, and details and proportions of all different layers, and use of confidence interval, revealed a high degree of sensitivity of Aleppo pine to this extreme environment. In the present study, non-significant thickness variations of the cell wall plus cuticle among current- and first-year-old needles of both fumigated and non fumigated trees have been found. However, at the ultrastructural level, significant variations in cell wall and total cuticle thickness, especially within the three zones of B1 fibrillar layer, revealed different equilibria for each of the four types of material. Using energy dispersive X-ray microanalysis, no sulphur was found in either cuticle or epidermal cells, but the presence of H2S in the fumarole gas is suspected to cause indirect and/or direct cuticle alterations of wax structure. Ultrastructural characters of plant cuticles related to emission of volcanic gases during the geological past are also discussed. Among these considerations, an identification key enabling distinction between non fumigated and fumigated materials with 9 characters, provides a good tool detecting the influence of volcanism for extant and fossil plants.
    Description: Published
    Description: 1–17
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: restricted
    Keywords: Campi Flegrei ; Volcanic gases ; Pinus halepensis ; Hydrogen sulphide (H2S) ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 34
    Publication Date: 2017-04-04
    Description: The Pernicana–Provenzana Fault System is one of the most active tectonic systems of Mt. Etna and it plays an important role in the dynamic of the eastern flank of the volcano. Earthquakes occurring close to this structural trend have reached magnitudes up to 4.2, sometimes with coseismic surface faulting, and have caused severe damages to tourist resorts and villages in the vicinity of this structure. In the last decade, a large number of shocks, sometimes in the form of swarms, linked to Pernicana–Provenzana Fault System movements have been detected by the permanent local seismic network operating in eastern Sicily. In this paper, we report on the detailed study of the seismic activity occurring during the 2000–2009 time span in the Pernicana–Provenzana Fault System area. Firstly, we located 407 earthquakes using a standard location code and a 1D crustal velocity model. We then applied two different approaches to calculate precise hypocenter locations of the events. In particular, a non-linear code was adopted to obtain an estimate of the a posteriori Probability Density Function in 3D space for the hypocenter location. Moreover, a relative location of correlated event pairs was performed, using the double-difference method. These two different location approaches allowed defining with good accuracy, the most active and hazarding sectors of the structure. The results of these precise locations showed a tighter clustering in the epicenters and in focal depths, in comparison with standard locations. Earthquakes are located along the Pernicana–Provenzana Fault System, and are mainly clustered in two zones, separated by an area with very low rate of earthquakes occurrence, but characterized by the highest energy release. Depths of the foci are very shallow, ranging between the surface and about 3 km b.s.l. Kinematics of the Pernicana–Provenzana Fault System, revealed by the fault plane solutions computed for the most energetic earthquakes, highlights a predominant dip–slip and left strike movements along E–W oriented fault planes, in agreement with field observations.
    Description: Published
    Description: 16-26
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Etna volcano ; Pernicana–Provenzana Fault System ; Earthquakes ; Precise location ; Fault plane solutions ; Seismic strain release ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 35
    Publication Date: 2017-04-04
    Description: The chemistry of Yellowstone fumarole gases shows the existence of two component waters, type MC, influenced by the addition of deep mantle fluid, and type CC, influenced by crustal interactions (CC). MC is high in 3He/4He (22 Ra) and low in 4He/40Ar ( 1), reflecting input of deep mantle components. The other water is characterized by 4He concentrations 3–4 orders of magnitude higher than air-saturated meteoric water (ASW). These high He concentrations originate through circulation in Pleistocene volcanic rocks, as well as outgassing of Tertiary and older (including Archean) basement, some of which could be particularly rich in uranium, a major 4He source. Consideration of CO2–CH4–CO–H2O–H2 gas equilibrium reactions indicates equilibration temperatures from 170 C to 310 C. The estimated temperatures highly correlate with noble-gas variations, suggesting that the two waters differ in temperature. Type CC is 170 C whereas the MC is hotter, at 340 C. This result is similar to models proposed by previous studies of thermal water chemistry. However, instead of mixing the deep hot component simply with cold, meteoric waters we argue that addition of a 4He-rich component, equilibrated at temperatures around 170 C, is necessary to explain the range in fumarole gas chemistry.
    Description: Published
    Description: 265–278
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: restricted
    Keywords: hydrothermal fluids ; Yellowstone Plateau ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 36
    Publication Date: 2021-09-03
    Description: Gas hazard was evaluated in the three most important cold gas emission zones on the flanks of the quiescent Colli Albani volcano. These zones are located above structural highs of the buried carbonate basement which represents the main regional aquifer and the main reservoir for gas rising from depth. All extensional faults affecting the limestone reservoir represent leaking pathways along which gas rises to the surface and locally accumulates in shallow permeable horizons forming pressurized pockets that may produce gas blowout when reached by wells. The gas, mainly composed by CO2 (〉90 vol.%), contains appreciable quantities of H2S (0.35-6 vol.%), and both represent a potentially high local hazard. Both gases are denser than air and accumulate near ground where they may reach hazardous concentrations, and actually lethal accidents frequently occur to animals watering at local ponds. In order to evaluate the rate of degassing and the related hazard, CO2 and H2S diffuse soil flux surveys have been repeatedly carried out by accumulation chamber. The viscous gas flux of some important discrete emissions has been also evaluated and the CO2 and H2S air concentration measured by portable devises and by Tunable Diode Laser profiles. The minimum potential lethal concentration of the two gases (250 ppm for H2S and 8 vol.% for CO2) is 320 times higher for CO2, whereas the CO2/H2S concentration ratio in the emitted natural gas is significantly lower (15-159). This explains why H2S reaches hazardous, even lethal, concentrations more frequently than CO2. A relevant hazard exists for both gases in the depressed zones (channels, excavations) particularly in the non-windy early hours of the day.
    Description: Published
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: partially_open
    Keywords: gas hazard ; hydrogen sulfide ; carbon dioxide ; Colli Albani volcano ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 37
    Publication Date: 2017-04-04
    Description: We present the first application of a time reverse location method in a volcanic setting, for a family of long-period (LP) events recorded on Mt Etna. Results are compared with locations determined using a full moment tensor grid search inversion and cross-correlation method. From 2008 June 18 to July 3, 50 broad-band seismic stations were deployed on Mt Etna, Italy, in close proximity to the summit. Two families of LP events were detected with dominant spectral peaks around 0.9 Hz. The large number of stations close to the summit allowed us to locate all events in both families using a time reversal location method. The method involves taking the seismic signal, reversing it in time, and using it as a seismic source in a numerical seismic wave simulator where the reversed signals propagate through the numerical model, interfere constructively and destructively, and focus on the original source location. The source location is the computational cell with the largest displacement magnitude at the time of maximum energy current density inside the grid. Before we located the two LP families we first applied the method to two synthetic data sets and found a good fit between the time reverse location and true synthetic location for a known velocity model. The time reverse location results of the two families show a shallow seismic region close to the summit in agreement with the locations using a moment tensor full waveform inversion method and a cross-correlation location method.
    Description: In press
    Description: (11)
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Volcano seismology ; Computational seismology ; Wave propagation ; 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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  • 38
    Publication Date: 2017-04-03
    Description: After an earthquake, rapid, real-time assessment of hazards such as ground shaking and tsunami potential is important for early warning and emergency response. Tsunami potential depends on sea floor displacement, which is related to the length, L, width, W, mean slip, D, and depth, z, of earthquake rupture. Currently, the primary discriminant for tsunami potential is the centroid-moment tensor magnitude, MwCMT, representing the seismic potency LWD, and estimated through an indirect, inversion procedure. The obtained MwCMT and the implied LWD value vary with the depth of faulting, assumed earth model and other factors, and is only available 30 min or more after an earthquake. The use of more direct procedures for hazard assessment, when available, could avoid these problems and aid in effective early warning. Here we present a direct procedure for rapid assessment of earthquake tsunami potential using two, simple measures on P-wave seismograms – the dominant period on the velocity records, Td, and the likelihood that the high-frequency, apparent rupture-duration, T0, exceeds 50-55 sec. T0 can be related to the critical parameters L and z, while Td may be related to W, D or z. For a set of recent, large earthquakes, we show that the period-duration product TdT0 gives more information on tsunami impact and size than MwCMT and other currently used discriminants. All discriminants have difficulty in assessing the tsunami potential for oceanic strike-slip and back-arc or upper-plate, intraplate earthquake types. Our analysis and results suggest that tsunami potential is not directly related to the potency LWD from the “seismic” faulting model, as is assumed with the use of the MwCMT discriminant. Instead, knowledge of rupture length, L, and depth, z, alone can constrain well the tsunami potential of an earthquake, with explicit determination of fault width, W, and slip, D, being of secondary importance. With available real-time seismogram data, rapid calculation of the direct, period- duration discriminant can be completed within 6-10 min after an earthquake occurs and thus can aid in effective and reliable tsunami early warning.
    Description: In press
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: open
    Keywords: Earthquake dynamics ; Earthquake source observations ; Seismic monitoring ; Body waves ; Early warning ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 39
    Publication Date: 2017-04-04
    Description: Stress can undergo rapid temporal changes in volcanic environments, and this is particularly true during eruptions. We use two independent methods, coda wave interferometry (CWI) and shear wave splitting (SWS) analysis to track stress related wave propagation effects during the waning phase of the 2002 NE fissure eruption at Mt Etna. CWI is used to estimate temporal changes in seismic wave velocity, while SWS is employed to monitor changes in elastic anisotropy. We analyse seismic doublets, detecting temporal changes both in wave velocities and anisotropy, consistent with observed eruptive activity. In particular, syn-eruptive wave propagation changes indicate a depressurization of the system, heralding the termination of the eruption, which occurs three days later.
    Description: Published
    Description: 1779-1788
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Interferometry ; Seismic anisotropy ; Volcano seismology ; Volcano monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 40
    Publication Date: 2017-04-04
    Description: A seismic noise recording experiment has been carried out in the Campi Flegrei volcanic area from March 9 to 26, 2009 in the framework of the INGV-DPC 2007-2009 agreement (Project V1 – UNREST). The project aimed at the realization of an integrated method for the definition of the unrest phases at Campi Flegrei. 21 digital three-component seismic stations equipped with broad band seismometers have been added to the existing 11 digital stations already deployed in the area. The preliminary results show a correlation between the seismic noise level and the anthropic activity, whereas the meteorological conditions seem affecting the low frequency seismic noise. These results are important to define the detection thresholds of the seismic signals generated during a possible renewal phase of the volcanic activity.
    Description: Published
    Description: 1-21
    Description: N/A or not JCR
    Description: open
    Keywords: Campi Flegrei ; seismic noise ; spectral analysis ; wave polarization ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
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  • 41
    Publication Date: 2020-11-12
    Description: Fluid geochemistry monitoring in the Azores involves the regular sampling and analysis of gas discharges from fumaroles and measurements of CO2 diffuse soil gas emissions. Main degassing areas under monitoring are associated with hydrothermal systems of active central volcanoes in S. Miguel, Terceira and Graciosa islands. Fumarole discharge analysis since 1991 show that apart from steam these gas emissions are CO2 dominated with H2S, H2, CH4 and N2 in minor amounts. Mapping of CO2 diffuse soil emissions in S. Miguel Island lead to the conclusion that some inhabited areas are located within hazard-zones. At Furnas village, inside Furnas volcano caldera, about 62% of the 896 houses are within the CO2 anomaly, 5% being in areas of moderate to high risk. At Ribeira Seca, on the north flank of Fogo volcano, few family houses were evacuated when CO2 concentrations in the air reached 8 mol%. To assess and analyse the CO2 soil flux emissions, continuous monitoring stations were installed in S. Miguel (2), Terceira and Graciosa islands. The statistical analysis of the data showed that some meteorological parameters influence the CO2 flux. The average of CO2 flux in S. Miguel stations ranges from 250 g/m2/d at Furnas volcano to 530 g/m2/d at Fogo volcano. At Terceira Island it is about 330 g/m2/d and at Graciosa 4400 g/m2/d.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: volcanology ; geochemistry ; soil degassing ; monitoring ; risk ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 42
    Publication Date: 2019-11-04
    Description: In order to verify the duration magnitude MD we calculated local magnitude ML values of 288 earthquakes occurring from October 2002 to April 2003 at Mt. Etna. The analysis was computed at three digital stations of the permanent seismic network of Istituto Nazionale di Geofisica e Vulcanologia of Catania, using the relationship ML = logA+alog?-b, where A is maximum half-amplitude of the horizontal component of the seismic recording measured in mm and the term «+alog?-b» takes the place of the term «-logA0» of Richter relationship. In particular, a = 0.15 for ?〈200 km, b=0.16 for ?〈200 km. Duration magnitude MD values, moment magnitude MW values and other local magnitude values were compared. Differences between ML and MD were obtained for the strong seismic swarms occurring on October 27, during the onset of 2002-2003 Mt. Etna eruption, characterized by a high earthquake rate, with very strong events (seismogram results clipped in amplitude on drum recorder trace) and high level of volcanic tremor, which not permit us to estimate the duration of the earthquakes correctly. ML and MD relationships were related and therefore a new relationship for MD is proposed. Cumulative strain release calculated after the eruption using ML values is about 1.75E+06 J1/2 higher than the one calculated using MD values.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: local magnitude ; Mt. Etna ; volcano seismicity ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 43
    Publication Date: 2019-11-04
    Description: Noble gas solubility in silicate melts and glasses has gained a crucial role in Earth Sciences investigations and in the studies of non-crystalline materials on a micro to a macro-scale. Due to their special geochemical features, noble gases are in fact ideal tracers of magma degassing. Their inert nature also allows them to be used to probe the structure of silicate melts. Owing to the development of modern high pressure and temperature technologies, a large number of experimental investigations have been performed on this subject in recent times. This paper reviews the related literature, and tries to define our present state of knowledge, the problems encountered in the experimental procedures and the theoretical questions which remain unresolved. Throughout the manuscript I will also try to show how the thermodynamic and structural interpretations of the growing experimental dataset are greatly improving our understanding of the dissolution mechanisms, although there are still several points under discussion. Our improved capability of predicting noble gas solubilities in conditions closer to those found in magma has allowed scientists to develop quantitative models of magma degassing, which provide constraints on a number of questions of geological impact. Despite these recent improvements, noble gas solubility in more complex systems involving the main volatiles in magmas, is poorly known and a lot of work must be done. Expertise from other fields would be extremely valuable to upcoming research, thus focus should be placed on the structural aspects and the practical and commercial interests of the study of noble gas solubility.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: noble gases ; solubility ; degassing ; silicate melts ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 44
    Publication Date: 2019-11-04
    Description: We present an empirical model of sulphur solubility that allows us to calculate f S2 if P, T, fO2 and the melt composition, including H2O and S, are known. The model is calibrated against three main experimental data bases consisting in both dry and hydrous silicate melts. Its prime goal is to calculate the f S2 of hydrous basalts that currently lack experimental constraints of their sulphur solubility behaviour. Application of the model to Stromboli, Vesuvius, Vulcano and Etna eruptive products shows that the primitive magmas found at these volcanoes record f S2 in the range 0.1-1 bar. In contrast, at all volcanoes the magmatic evolution is marked by dramatic variations in f S2 that spreads over up to 9 orders of magnitude. The f S2 can either increase during differentiation or decrease during decompression to shallow reservoirs, and seems to be related to closed versus open conduit conditions, respectively. The calculated f S2 shows that the Italian magmas are undersaturated in a FeS melt, except during closed conduit conditions, in which case differentiation may eventually reach conditions of sulphide melt saturation. The knowledge of f S2, fO2 and fH2O allows us to calculate the fluid phase composition coexisting with magmas at depth in the C-O-H-S system. Calculated fluids show a wide range in composition, with CO2 mole fractions of up to 0.97. Except at shallow levels, the fluid phase is generally dominated by CO2 and H2O species, the mole fractions of SO2 and H2S rarely exceeding 0.05 each. The comparison between calculated fluid compositions and volcanic gases shows that such an approach should provide constraints on both the depth and mode of degassing, as well as on the amount of free fluid in magma reservoirs. Under the assumption of a single step separation of the gas phase in a closed-system condition, the application to Stromboli and Etna suggests that the main reservoirs feeding the eruptions and persistent volcanic plumes at these volcanoes might contain as much as 5 wt% of a free fluid phase. Consideration of the magma budget needed to balance the amounts of volatiles emitted in the light of these results shows that the amount of nonerupted magma could be overestimated by as much as one order of magnitude.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: sulphur ; hydrous basalts ; volcanic gas ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 45
    Publication Date: 2019-11-04
    Description: A compendium of diffusion measurements and their Arrhenius equations for water, carbon dioxide, sulfur, fluorine, and chlorine in silicate melts similar in composition to natural igneous rocks is presented. Water diffusion in silicic melts is well studied and understood, however little data exists for melts of intermediate to basic compositions. The data demonstrate that both the water concentration and the anhydrous melt composition affect the diffusion coefficient of water. Carbon dioxide diffusion appears only weakly dependent, at most, on the volatilefree melt composition and no effect of carbon dioxide concentration has been observed, although few experiments have been performed. Based upon one study, the addition of water to rhyolitic melts increases carbon dioxide diffusion by orders of magnitude to values similar to that of 6 wt% water. Sulfur diffusion in intermediate to silicic melts depends upon the anhydrous melt composition and the water concentration. In water-bearing silicic melts sulfur diffuses 2 to 3 orders of magnitude slower than water. Chlorine diffusion is affected by both water concentration and anhydrous melt composition; its values are typically between those of water and sulfur. Information on fluorine diffusion is rare, but the volatile-free melt composition exerts a strong control on its diffusion. At the present time the diffusion of water, carbon dioxide, sulfur and chlorine can be estimated in silicic melts at magmatic temperatures. The diffusion of water and carbon dioxide in basic to intermediate melts is only known at a limited set of temperatures and compositions. The diffusion data for rhyolitic melts at 800°C together with a standard model for the enrichment of incompatible elements in front of growing crystals demonstrate that rapid crystal growth, greater than 10-10 ms-1, can significantly increase the volatile concentrations at the crystal-melt interface and that any of that melt trapped by the formation of melt inclusions may not be representative of the bulk melt. However, basaltic melt inclusions trapped at 1300°C are more likely to contain bulk melt concentrations of water and carbon dioxide.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: diffusion ; silicate melts ; volatiles ; water ; carbon dioxide ; sulfur ; fluorine ; igneous processes ; chlorine ; melt inclusion ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 46
    Publication Date: 2019-11-04
    Description: We have characterized the textures of pumice clasts from Phlegraean Fields to gain insights into the conduit flow-dynamics of alkaline explosive eruptions. Vesicularities, vesicle number densities, and vesicle sizes and shapes were measured to obtain the bulk and groundmass properties of the juvenile fraction of Campanian Ignimbrite (CI) and Agnano Monte Spina (AMS) eruptions. The results report the coexistence of three end-member pumice types in the deposits of both eruptions, 1) microvesicular, 2) tube and 3) expanded, which differ according to clast morphology and the macro- to microscopic vesicle texture. Vesicularities (0.85-0.94 for CI, 0.51-0.91 for AMS) and vesicle number densities (2-4×105 cm-2 in CI, 3×105-106 cm-2 in AMS) span quite a wide range in all the three pumice types. Overall, tube pumices exhibit the highest bulk (0.89) and groundmass (CI 0.85, AMS 0.82) average vesicle volume fractions but the lowest average vesicle number densities (CI 2×105, AMS 4×105 cm-2). Comparison with textures of calc-alkaline pumices has revealed many similarities and points to a common origin and distribution of the products from both magma compositions within the volcanic conduit. In addition, the results of the textural analysis were interpreted in the light of the conduit flow modeling of Phlegraean Fields eruptions. The comparison of textural observations with results from simulations of conduit magma ascent has exhibited a good agreement between measured and numerically calculated vesicularities for both compositions, helping to constrain the overall dynamics of alkaline versus calc-alkaline eruptions.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: Phlegraean Fields ; Plinian eruptions ; vesicle textures ; magma ascent dynamics ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 47
    Publication Date: 2019-11-04
    Description: Volatile components in magma strongly influence many physical properties of melts and minerals. The temperature resolved degassing analysis of volcanic crystalline and vitreous rocks gives detailed information about volatile compounds in the melt. Aspecial high-temperature mass-spectrometry device in combination with a thermo-balance allows a quantitative determination of different volatile species. It enables a differentiation between the primary gas content in the magma and the gas released from decomposition of secondary alteration products. The gas release profiles give the following indications: i) during the littoral explosions of Pahoehoe lava the content of volatiles is not changed by interaction with air or sea water; ii) the degassing profiles of vitreous black sand verify the primary content of volatiles in the erupted melt, only CO2 was detected; iii) the oxygen release profile gives significant indications for oxygen undersaturation of the erupted magma; iv) remelting of black sand in air at 1450°C for 0.45 h causes an oxygen saturation of the basaltic melt; v) remelting of black sand in argon atmosphere confirms the oxygen undersaturation of the melt; vi) remelting of black sand-black shale mixtures affects a significant change in the degassing profiles, especially in CO2-release. With the first investigations we can demonstrate that gas release curves of volcanic rocks are qualified for a) detection of the primary gas content of erupted magma; b) detection of alteration processes of the igneous glass; c) detection of contamination of the magma with adjacent rocks.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: volatiles ; magmatic rocks ; basaltic glass ; degassing ; Hawaiian lava ; remelting ; blacksand ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 48
    Publication Date: 2019-11-04
    Description: The EQ3/6 software package, version 7.2 was successfully used to model scrubbing of magmatic gas by pure water at 0.1 MPa, in the liquid and liquid-plus-gas regions. Some post-calculations were necessary to account for gas separation effects. In these post-calculations, redox potential was considered to be fixed by precipitation of crystalline a-sulfur, a ubiquitous and precocious process. As geochemical modeling is constrained by conservation of enthalpy upon water-gas mixing, the enthalpies of the gas species of interest were reviewed, adopting as reference state the liquid phase at the triple point. Our results confirm that significant emissions of highly acidic gas species (SO2(g), HCl(g), and HF(g)) are prevented by scrubbing, until dry conditions are established, at least locally. Nevertheless important outgassing of HCl(g) can take place from acid, HCl-rich brines. Moreover, these findings support the rule of thumb which is generally used to distinguish SO2-, HCl-, and HF-bearing magmatic gases from SO2-, HCl-, and HF-free hydrothermal gases.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: magmatic gas ; magma degassing ; hydrothermalsystem ; crater lake ; meteoric water ; scrubbing ; reaction path modeling ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 49
    Publication Date: 2019-11-04
    Description: An overview of novel laser techniques suitable for volcanic monitoring, based on different kinds of infrared laser sources, is presented. Their main advantages and drawbacks are discussed focusing on the achievable sensitivity and precision levels in analysis of gaseous species. Some of the most recent experimental results obtained in laboratory development as well as in field tests of home-built laser spectrometers are reported. New perspectives in optical devices aimed at geochemical and geophysical applications are also considered.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: diode laser ; absorption spectroscopy ; optical fiber ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 50
    Publication Date: 2019-11-04
    Description: Thermodynamic modelling of magmatic gases shows that SiF4 may be an important F-bearing species at the high pressures typical of magma reservoirs. Upon decompression during degassing, SiF4 will react with water vapour to form HF and silica. Common magmatic gases of high-T fumaroles seem to contain too little SiF4 to be a significant source of silica, except if extremely large amounts of gas percolate through a small volume of rock, as is the case in lava domes. Only if fluorine contents of the gases exceed 1 mol% detectable amounts of silica may be formed, but such high fluorine contents have not yet been observed in natural gases. Alternatively, silica may be formed by heating of cool SiF4-rich gases circulating in cooling lava bodies. We suggest that these mechanisms may be responsible for the deposition of crystalline silica, most probably cristobalite, observed in vesicles in lavas from Lewotolo volcano (Eastern Sunda Arc, Indonesia). Silica occurs as vapour-crystallised patches in vesicles, and is sometimes associated with F-phlogopite, which further supports F-rich conditions during deposition. Because of the connection between F-rich conditions and high-K volcanism, we propose that late-stage gaseous transport and deposition of silica may be more widespread in K-rich volcanoes than elsewhere, and long-term exposure to ash from eruptions of such volcanoes could therefore carry an increased risk for respiratory diseases. The dependence of SiF4/HF on temperature reported here differs from the current calibration used for temperature measurements of fumarolic gases by remote sensing techniques, and we suggest an updated calibration.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: SiF4 ; vapour crystallisation ; silica ; degassing ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics
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  • 51
    Publication Date: 2019-11-04
    Description: An Eulerian model for passive gas dispersion based on the K-theory for turbulent diffusion, coupled with a mass consistent wind model is presented. The procedure can be used to forecast gas concentration over large and complex terrains. The input to the model includes the topography, wind measurements from meteorological stations, atmospheric stability information and gas flow rate from the ground sources. Here, this model is applied to study the distribution of the CO2 discharged from the hot sources of the Solfatara Volcano, Naples, Italy, where the input data were measured during a 15 day campaign in June 2001 carried out to test an Eddy Covariance (EC) station by Osservatorio Vesuviano-INGV, Naples.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: gas dispersion ; volcanic gas ; K-theory ; computer model ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 52
    Publication Date: 2019-11-04
    Description: The paper addresses some fundamental aspects of the dynamics of dense granular flows down inclines relevant to pyroclastic density currents. A simple mechanistic framework is presented to analyze the dynamics of the frontal zone, with a focus on the establishment of conditions that promote air entrainment at the head of the current and motion-induced self-fluidization of the flow. The one-dimensional momentum balance on the current along the incline is considered under the hypothesis of strongly turbulent flow and pseudo-homogeneous behaviour of the two-phase gas-solid flow. Departures from one-dimensional flow in the frontal region are also analyzed and provide the key to the assessment of air cross-flow and fluidization of the solids in the head of the current. The conditions for the establishment of steady motion of pyroclastic flows down an incline, in either the fluidized or «dry» granular states, are examined.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: pyroclastic flow ; fluidization ; gravity current ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 53
    Publication Date: 2019-11-04
    Description: The Campanian volcanism develops near the sea. Therefore, the geophysical study of the marine environment is a key to a better understanding of the tectonic evolution and the origin of volcanism in the area. An abundance of high quality seismic data in the marine sector, where little direct information is available, is critical to the study of Campanian volcanism. This paper concerns the reprocessing of a seismic reflection dataset acquired in Naples Bay and processed during 1973. Even though the overall data quality was high for that time, of course their acquisition technological limits have been overcome by the new processing. Our reprocessing aimed at: 1) reduction of random noise in the data; 2) removal of unwanted coherent events; 3) reduction of spatial aliasing by means of trace interpolation on Commod Shot Point (CSP) gathering; 4) improvement of resolution of the seismic wavelet with spiking deconvolution algorithms and finally 5) reposition of reflectors in their correct locations in the space-TWT domain by means of dip moveout and post-stack time migration. A comparison between the new and old data shows that the new sections are characterized by a much higher S/N ratio. Diffraction hyperbole has been collapsed. Reverberations, ghosts and multiples have been removed or greatly attenuated, especially between the reflectors of interest, allowing us to follow them with more detail and with greater continuity. Furthermore, data resolution has been boosted by the reprocessing, allowing the interpreter to evaluate reflector position and continuity in greater detail. The reinterpretation phase of such lines, that is already in an advanced stage, will therefore allow us to gain new insights into the structural setting of the bay, with the aim of exploring the connection between tectonics and volcanism.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: marine geophysics ; seismic reflection ; 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::05.02. Data dissemination::05.02.02. Seismological data
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  • 54
    Publication Date: 2019-11-04
    Description: Phase equilibrium relationships in igneous systems can be estimated using empirical mathematical models based on multi-component regular solution formulae. Although these provide useable results within the fitted region, they can give very misleading values outside the compositional range of curve fitting. Moreover, they usually give poor estimates of the well-characterized melting relations of simple systems and do not relate to the large body of thermodynamic activity data available in the metallurgical literature, nor to spectroscopic, diffraction or computational models of silicate melt properties. The aim of this paper is to extend previous acid-base models of silicate melts and to use a quasi-chemical model to calculate the activities of quasi-chemical silicate mixing units, or structons, from combinations of the oxo-species used in quasi-chemical and polymer models to calculate oxide activities in metallurgy.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: silicate melt ; acid-base ; oxide melt ; thermodynamic properties ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics
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  • 55
    Publication Date: 2019-11-04
    Description: The Thermodynamics of quasi-chemical and polymeric models are briefly reviewed. It is shown that the two classes are mutually consistent, and that opportune conversion of the existing quasi-chemical parameterization of binary interactions in MO-SiO2 joins to polymeric models may be afforded without substantial loss of precision. It is then shown that polymeric models are extremely useful in deciphering the structural and reactive properties of silicate melts and glasses. They not only allow the Lux-Flood character of the dissolved oxides to be established, but also discriminate subordinate strain energy contributions to the Gibbs free energy of mixing from the dominant chemical interaction terms. This discrimination means that important information on the short-, medium- and long-range periodicity of this class of substances can be retrieved from thermodynamic analysis. Lastly, it is suggested that an important step forward in deciphering the complex topology of the inhomogeneity ranges observed at high SiO2 content can be performed by applying SCMF theory and, particularly, Matsen-Schick spectral analysis, hitherto applied only to rubberlike materials.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: silicate melts ; structure ; entropy ; unmixing ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics
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  • 56
    Publication Date: 2019-11-04
    Description: In order to describe and quantify the reactivity of silicate melts, the ionic notation provided by the Temkin formalism has been historically accepted, giving rise to the study of melt chemical equilibria in terms of completely dissociated ionic species. Indeed, ionic modelling of melts works properly as long as the true extension of the anionic matrix is known. This information may be attained in the framework of the Toop-Samis (1962a,b) model, through a parameterisation of the acid-base properties of the dissolved oxides. Moreover, by combining the polymeric model of Toop and Samis with the «group basicity» concept of Duffy and Ingram (1973, 1974a,b, 1976) the bulk optical basicity (Duffy and Ingram, 1971; Duffy, 1992) of molten silicates and glasses can be split into two distinct contributions, i.e. the basicity of the dissolved basic oxides and the basicity of the polymeric units. Application to practical cases, such as the assessment of the oxidation state of iron, require bridging of the energetic gap between the standard state of completely dissociated component (Temkin standard state) and the standard state of pure melt component at P and T of interest. On this basis it is possible to set up a preliminary model for iron speciation in both anhydrous and hydrous aluminosilicate melts. In the case of hydrous melts, I introduce both acidic and basic dissociation of the water component, requiring the combined occurrence of H+ cations, OH- free anions and, to a very minor extent, of T-OH groups. The amphoteric behaviour of water revealed by this study is therefore in line with the earlier prediction of Fraser (1975).
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: polymerisation ; basicity ; oxidationstate ; water speciation ; Temkin model ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics
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  • 57
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    INGV
    Publication Date: 2019-11-04
    Description: The strong influence of physical conditions during magma formation on Fe equilibria offers a large variety of possibilities to deduce these conditions from Fe-bearing phases and phase assemblages found in magmatic rocks. Conditions of magma genesis and their evolution are of major interest for the understanding of volcanic eruptions. A brief overview on the most common methods used is given together with potential problems and limitations. Fe equilibria are not only sensitive to changes in intensive parameters (especially T and fO2) and extensive parameters like composition also have major effects, so that direct application of experimentally calibrated equilibria to natural systems is not always possible. Best estimates for pre-eruptive conditions are certainly achieved by studies that relate field observations directly to experimental observations for the composition of interest using as many constraints as possible (phase stability relations, Fe-Ti oxides, Fe partitioning between phases, Fe oxidation state in glass etc.). Local structural environment of Fe in silicate melts is an important parameter that is needed to understand the relationship between melt transport properties and melt structure. Assignment of Fe co-ordination and its relationship to the oxidation state seems not to be straightforward. In addition, there is considerable evidence that the co-ordination of Fe in glass differs from that in the melt, which has to be taken into account when linking melt structure to physical properties of silicate melts at T and P.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: iron ; silicate melt ; redox conditions ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 58
    Publication Date: 2019-11-04
    Description: Experimental studies of Cl solubility in trachytic to phonolitic melts provide insights into the capacity of alkaline magmas to transport Cl from depth to the earths surface and atmosphere, and information on Cl solubility variations with pressure, temperature and melt or fluid composition is crucial for understanding the reasons for variations in Cl emissions at active volcanoes. This paper provides a brief review of Cl solubility experiments conducted on a range of trachytic to phonolitic melt compositions. Depending on the experimental conditions the melts studied were in equilibrium with either a Cl-bearing aqueous fluid or a subcritical assemblage of low- Cl aqueous fluid + Cl-rich brine. The nature of the fluid phase(s) was identified by examination of fluid inclusions present in run product glasses and the fluid bulk composition was calculated by mass balance. Chlorine concentrations in the glass increase with increasing Cl molality in the fluid phase until a plateau in Cl concentration is reached when melt coexists with aqueous fluid + brine. With fluids of similar Cl molality, higher Cl concentrations are observed in peralkaline phonolitic melts compared with peraluminous phonolitic melts; overall the Cl concentrations observed in phonolitic and trachytic melts are approximately twice those found in calcalkaline rhyolitic melts under similar conditions. The observed negative pressure dependence of Cl solubility implies that Cl contents of melts may actually increase during magma decompression if the magma coexists with aqueous fluid and Cl-rich brine (assuming melt-vapor equilibrium is maintained). The high Cl contents (approaching 1 wt% Cl) observed in some melts/glasses from the Vesuvius and Campi Flegrei areas suggest saturation with a Cl-rich brine prior to eruption.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: alkaline magmas ; solubility ; chlorine ; supercritical fluid ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 59
    Publication Date: 2019-11-04
    Description: The effect of pressure, temperature, and melt composition on CO2 and H2O solubilities in aluminosilicate melts, coexisting with CO2-H2O fluids, is discussed on the basis of previously published and new experimental data. The datasets have been chosen so that CO2 and H2O are the main fluid components and the conclusions are only valid for relatively oxidizing conditions. The most important parameters controlling the solubilities of H2O and CO2 are pressure and composition of melt and fluid. On the other hand, the effect of temperature on volatile solubilities is relatively small. At pressures up to 200 MPa, intermediate compositions such as dacite, in which both molecular CO2 and carbonate species can be dissolved, show higher volatile solubilities than rhyolite and basalt. At higher pressures (0.5 to 1 GPa), basaltic melts can incorporate higher amounts of carbon dioxide (by a factor of 2 to 3) than rhyolitic and dacitic melts. Henrian behavior is observed only for CO2 solubility in equilibrium with H2O-CO2 fluids at pressures 〈100 MPa, whereas at higher pressures CO2 solubility varies nonlinearly with CO2 fugacity. The positive deviation from linearity with almost constant CO2 solubility at low water activity indicates that dissolved water strongly enhances the solubility of CO2. Water always shows non-Henrian solubility behavior because of its complex dissolution mechanism (incorporation of OH-groups and H2O molecules in the melt). The model of Newman and Lowenstern (2002), in which ideal mixing between volatiles in both fluid and melt phases is assumed, reproduces adequately the experimental data for rhyolitic and basaltic compositions at pressures below 200 MPa but shows noticeable disagreement at higher pressures, especially for basalt. The empirical model of Liu et al. (2004) is applicable to rhyolitic melts in a wide range of pressure (0-500 MPa) and temperature (700- 1200°C) but cannot be used for other melt compositions. The thermodynamic approach of Papale (1999) allows to calculate the effect of melt composition on volatile solubilities but needs an update to account for more recent experimental data. A disadvantage of this model is that it is not available as a program code. The review indicates a crucial need of new experimental data for scarcely investigated field of pressures and fluid compositions and new models describing evident non-ideality of H-C-O fluid solubility in silicate melts at high pressures.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: CO2 ; H2O ; solubility ; mixed fluid ; silicate melt ; experimental data ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 60
    Publication Date: 2019-11-04
    Description: Volcanic eruptions are unsteady multiphase phenomena, which encompass many inter-related processes across the whole range of scales from molecular and microscopic to macroscopic, synoptic and global. We provide an overview of recent advances in numerical modelling of volcanic effects, from conduit and eruption column processes to those on the Earth s climate. Conduit flow models examine ascent dynamics and multiphase processes like fragmentation, chemical reactions and mass transfer below the Earth surface. Other models simulate atmospheric dispersal of the erupted gas-particle mixture, focusing on rapid processes occurring in the jet, the lower convective regions, and pyroclastic density currents. The ascending eruption column and intrusive gravity current generated by it, as well as sedimentation and ash dispersal from those flows in the immediate environment of the volcano are examined with modular and generic models. These apply simplifications to the equations describing the system depending on the specific focus of scrutiny. The atmospheric dispersion of volcanic clouds is simulated by ash tracking models. These are inadequate for the first hours of spreading in many cases but focus on long-range prediction of ash location to prevent hazardous aircraft - ash encounters. The climate impact is investigated with global models. All processes and effects of explosive eruptions cannot be simulated by a single model, due to the complexity and hugely contrasting spatial and temporal scales involved. There is now the opportunity to establish a closer integration between different models and to develop the first comprehensive description of explosive eruptions and of their effects on the ground, in the atmosphere, and on the global climate.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: numerical modeling ; explosive volcanic eruptions ; conduit flow ; multiphase flow simulation ; stratospheric sulfate aerosol ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 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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  • 61
    Publication Date: 2019-11-04
    Description: Measurements of volcanic gas composition and flux are crucial to probing and understanding a range of magmatic, hydrothermal and atmospheric interactions. The value of optical remote sensing methods has been recognised in this field for more than thirty years but several recent developments promise a new era of volcanic gas surveillance. This could see much higher time- and space-resolved data-sets, sustained at individual volcanoes even during eruptive episodes. We provide here an overview of these optical methods and their application to ground-based volcano monitoring, covering passive and active measurements in the ultraviolet and infrared spectral regions. We hope thereby to promote the use of such devices, and to stimulate development of new optical techniques for volcanological research and monitoring.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: volcano monitoring ; volcano plumes ; IR and UV spectoscopy ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 62
    Publication Date: 2019-11-04
    Description: Based on characteristics of the distribution pattern of the western Eger Rift spring gases, a distribution pattern is presented for the gases of the French Massif Central. The central parts of these areas with ascending magmatic CO2 are characterised by high gas fluxes, high CO2 contents of up to 99.99 vol% and isotopially heavy CO2. In the peripheries, the decrease of d13C values of CO2 and CO2 contents in the gas phase is compensated by a rise in N2 contents. It can be demonstrated that gas fractionation in contrary to mixtures with isotopically light biogenic or crustal CO2 controls the distribution pattern of gas composition and isotopic composition of CO2 in these spring gases. Dissolution of CO2 results in formation of HCO3 causing isotope fractionation of CO2 and an enrichment of N2 in the gas phase. With multiple equilibrations, values of about 17 or lower are obtained. The scale of gas alteration depends on the gas flux and the gas-water ratios respectively and can result in N2-rich gases. Essential for the interpretation are gas flux measurements with mass balances derived for most of the springs. Without such mass balances it is not possible to discriminate between mixture and fractionation. The processes of isotopic and chemical solubility fractionations evidently control the gas distribution pattern in other regions as well.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: Eger Rift ; French Massif Central ; Eifel ; carbon dioxide ; gas fractionation ; isotope composition ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 63
    Publication Date: 2019-11-04
    Description: We report preliminary observations on possible correlations between anomalies of subsoil radon concentration and geodynamical events on Mt. Etna. In recent years several studies have been carried out on radon as a precursor of geophysical events, most of them performed either on tectonic or volcanic areas. The peculiarity of our investigation lies on the choice of the etnean region, in which tectonic and volcanic features are both present. In order to characterize Mt. Etna features by investigating radon gas in soil, two stations were located along the NE-SW direction on Mt. Etna. Each of the two stations is fitted with a radon detector, a 3D seismic station and a meteorological station. Differences in the radon concentration trend in the data from north and south flanks could be linked to different faulting mechanisms and then to different mechanisms of radon uprising. The increase in soil radon concentration could be related to both seismic and volcanic events.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: radon ; geodynamical precursor ; Mt. Etna ; 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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  • 64
    Publication Date: 2024-05-09
    Description: On 3rd November 2002, at about 3 km off-shore of Panarea Island (Aeolian Islands, Southern Italy), a series of gas vents suddenly and violently opened from the seafloor at the depth of 10-15 m, with an unusually high gas flux and superimposing on the already existing submarine fumarolic field. Starting from the 12th November 2002 a discontinuous geochemical monitoring program was carried out. The emissions consisted in an emulsion whose liquid phase derived from condensation of an uprising vapor phase occurring close to the fluid outlets without significant contamination by seawater. The whole composition of the fluids was basically H2O- and CO2-dominated, with minor amounts of typical «hydrothermal» components (such as H2S, H2, CO and light hydrocarbons), atmospheric-related compounds, and characterized by the occurrence of a significant magmatic gas fraction (mostly represented by SO2, HCl and HF). According to the observed temporal variability of the fluid compositions, between November and December 2002 the hydrothermal feeding system was controlled by oxidizing conditions due to the input of magmatic gases. The magmatic degassing phenomena showed a transient nature, as testified by the almost complete disappearance of the magmatic markers in a couple of months and by the restoration, since January 2003, of the chemical features of the existing hydrothermal system. The most striking feature of the evolution of the «Panarea degassing event» was the relatively rapid restoration of the typical reducing conditions of a stationary hydrothermal system, in which the FeO/Fe1.5O redox pair of the rock mineral phases has turned to be the dominating redox controlling system.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: Aeolian Islands ; Panarea ; submarine fumaroles ; gas chemistry ; geochemical monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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    Type: article
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