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  • 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques  (21)
  • 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes
  • 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes
  • Elsevier  (40)
  • American Institute of Physics
  • Essen : Verl. Glückauf
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
  • 2005-2009  (40)
Collection
Keywords
Publisher
Years
Year
  • 1
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    Carbon dioxide of Pu`u`O`o volcanic plume at Kilauea retrieved by AVIRIS hyperspectral data (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A remote sensing approach permits for the first time the derivation of a map of the carbon dioxide concentration in a volcanic plume. The airborne imaging remote sensing overcomes the typical difficulties associated with the ground measurements and permits rapid and large views of the volcanic processes together with the measurements of volatile components exolving from craters. Hyperspectral images in the infrared range (1900–2100 nm), where carbon dioxide absorption lines are present, have been used. These images were acquired during an airborne campaign by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) over the Pu`u` O`o Vent situated at the Kilauea East Rift zone, Hawaii. Using a radiative transfer model to simulate the measured up-welling spectral radiance and by applying the newly developed mapping technique, the carbon dioxide concentration map of the Pu`u` O`o Vent plume were obtained. The carbon dioxide integrated flux rate were calculated and a mean value of 396±138 t d−1 was obtained. This result is in agreement, within the measurements errors, with those of the ground measurements taken during the airborne campaign.
    Description: Published
    Description: 3192–3199
    Description: 1.10. TTC - Telerilevamento
    Description: JCR Journal
    Description: partially_open
    Keywords: Hyperspectral data ; Volcanic plume ; Carbon dioxide ; AVIRIS ; Kilauea ; 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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  • 2
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    Insight on recent Stromboli eruption inferred from terrestrial and satellite ground deformation measurements (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The multi-parametric permanent system (tilt and GPS networks, robotized geodetic station) for monitoring ground deformation at Stromboli volcano was set up in the 1990s and later greatly improved during the effusive event of 2002–2003. Unlike other volcanoes, e.g. Mt. Etna, the magnitude of ground deformation signals of Stromboli is very small and through the entire period of operation of the monitoring system, only two major episodes of deformation, in 1994–1995 and 2000, which did not lead to an eruption but rather pure intrusion, were measured. Similarly to the 2002–2003 eruption, no important deformations were detected in the months before the 2007 eruption. However, unlike the 2002–2003 eruption, GPS and tilt stations recorded a continuous deflation during the entire 2007 eruption, which allowed us to infer a vertical elongated prolate ellipsoidal source, centered below the summit craters at depth of about 2.8 km b.s.l. Due to its geometry and position, this source simulates an elongated plumbing system connecting the deeper LP magma storage (depth from 5 to 10 km) with the HP shallower storage (0.8–3 km), both previously identified by petrologic and geochemical studies. This result represents the first contribution of geophysics to the definition of the plumbing system of Stromboli at intermediate depth. Finally, no deformation due to the plumbing system was measured for a long time after the end of the eruption. Meanwhile, the new terrestrial geodetic monitoring system installed within the Sciara del Fuoco, on the lava fan formed during the eruption, indicated that during the first months after the end of the eruption the ground velocity progressively decreased in time, suggesting that part of the deformation was due to the thermal contraction of the lava flow.
    Description: Published
    Description: 172-181
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Stromboli ; Ground Deformation ; source modelling ; flank instability ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.03. Geodesy::04.03.09. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 3
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    Effects of soil gas permeability and recirculation flux on soil CO2 flux measurements performed using a closed dynamic accumulation chamber (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Dynamic accumulation chamber methods have been extensively used to estimate the total output of CO2 released from active volcanic area. In order to asses the performance and reliability of a closed dynamic system several tests were carried out with different soil permeabilities and soil CO2 fluxes. A special device was used to create a constant one-dimensional CO2 flux through a soil column with a known permeability. Three permeabilities were investigated, ranging between 3.6 × 10− 2 and 3.5 × 10 μm2, as were several CO2 fluxes (ranging between 1.1 × 10− 6 and 6.3 × 10− 5 kg m− 2 s− 1). The results highlight that the accuracy of soil CO2 flux measurements strictly depends on the soil gas permeability and the soil CO2 flux regimen. Generally chamber measurements underestimate CO2 fluxes at low soil permeability and low soil CO2 fluxes, whereas appreciable overestimations occur for high permeability soil, especially for high soil CO2 fluxes. Other tests carried out with different settings for the measurement device, such as the chamber volume and the flux of the pump used to recirculate air through the chamber and the gas analyzer (recirculation flux), revealed a strong dependence of the closed dynamic chamber measurements on the recirculation flux. Low recirculation fluxes (0.2–0.4 l min− 1) decreased the performance of the measurement system, causing underestimations of the actual soil CO2 flux, whereas higher values (0.6–1.0 l min− 1) resulted in overestimations, especially for elevated soil CO2 fluxes. An empirical equation was deduced to allow accumulation chamber fluxes to be calculated very accurately based on soil gas permeabilities measured in the field.
    Description: Published
    Description: 387-393
    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: reserved
    Keywords: Soil CO2 flux measuraments ; Closed dynamic chamber ; soil gas permeability ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 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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  • 4
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    Geochemical evaluation of observed changes in volcanic activity during the 2007 eruption at Stromboli (Italy) (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: On February 27, 2007 a new eruption started at Stromboli that lasted until April 2 and included a paroxysmal explosion on March 15. Geochemical monitoring carried out over several years revealed some appreciable variations that preceded both the eruption onset and the explosion. The carbon dioxide (CO2) flux from the soil at Pizzo Sopra La Fossa markedly increased a few days before the eruption onset, and continued during lava effusion to reach its maximum value (at 90,000 g m−2 d−1) a few days before the paroxysm. Almost contemporarily, the δ13CCO2 of the SC5 fumarole located in the summit area increased markedly, peaking just before the explosion (δ13CCO2~−1.8‰). Following the paroxysm, helium (He) isotopes measured in the gases dissolved in the basal thermal aquifer sharply increased. Almost contemporarily, the automatic station of CO2 flux recorded an anomalous degassing rate. Also temperatures and the vertical thermal gradient, which had been measured since November 2006 in the soil at Pizzo Sopra La Fossa, showed appreciable variabilities that lasted until the end of the eruption. The geochemical variations indicated the degassing of a new batch of volatile-rich magma that preceded and probably fed the paroxysm. The anomalous 3He/4He ratio suggested that the ascent of a second batch of volatile-rich magma toward the surface was probably responsible of the resumption of the ordinary activity. A comparison with the geochemical variations observed during the 2002–2003 eruption indicated that the 2007 eruption was less energetic.
    Description: Published
    Description: 246-254
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: geochemistry ; eruption ; dissolved gases ; Stromboli ; volcanic activity ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 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 ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
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    Intrusion of eccentric dikes: The case of the 2001 eruption and its role in the dynamics of Mt. Etna volcano (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The 2001 eruption represents one of the most studied events both from volcanological and geophysical point of view on Mt. Etna. This eruption was a crucial event in the recent dynamics of the volcano, marking the passage from a period (March 1993–June 2001) of moderate stability with slow, continuous flank sliding and contemporaneous summit eruptions, to a period (July 2001 to present) of dramatically increased flank deformations and flank eruptions. We show new GPS data and high precision relocation of seismicity in order to demonstrate the role of the 2001 intrusive phase in this change of the dynamic regime of the volcano. GPS data consist of two kinematic surveys carried out on 12 July, a few hours before the beginning of the seismic swarm, and on 17 July, just after the onset of eruptive activity. A picture of the spatial distribution of the sin-eruptive seismicity has been obtained using the HypoDD relocation algorithm based on the double-difference (DD) technique. Modeling of GPS measurements reveals a southward motion of the upper southern part of the volcano, driven by a NNW–SSE structure showing mainly left-lateral kinematics. Precise hypocenter location evidences an aseismic zone at about sea level, where the magma upraise was characterized by a much higher velocity and an abrupt westward shift, revealing the existence of a weakened or ductile zone. These results reveal how an intrusion of a dike can severely modify the shallow stress field, triggering significant flank failure. In 2001, the intrusion was driven by a weakened surface, which might correspond to a decollement plane of the portion of the volcano affected by flank instability, inducing an additional stress testified by GPS measurements and seismic data, which led to an acceleration of the sliding flanks.
    Description: This work was funded by the Istituto Nazionale di Geofisica e Vulcanologia and by the Dipartimento per la Protezione Civile (Italy).
    Description: Published
    Description: 78–86
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: stress release ; dike ; volcano-tectonics ; flank instability ; Mt. Etna ; instrumental monitoring ; 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::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 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::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.99. General or miscellaneous ; 05. General::05.02. Data dissemination::05.02.02. Seismological data ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
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    New geological insights and structural control on fluid circulation in La Fossa cone (Vulcano, Aeolian Islands, Italy) (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Electric resistivity tomography (ERT), self-potential (SP), soil CO2 flux, and temperature are used to study the inner structure of La Fossa cone (Vulcano, Aeolian Islands). Nine profiles were performed across the cone with a measurement spacing of 20 m. The crater rims of La Fossa cone are underlined by sharp horizontal resistivity contrasts. SP, CO2 flux, and temperature anomalies underline these boundaries which we interpret as structural limits associated to preferential circulation of fluids. The Pietre Cotte crater and Gran Cratere crater enclose the main hydrothermal system, identified at the centre of the edifice on the base of low electrical resistivity values (b20 Ω m) and strong CO2 degassing, SP, and temperature anomalies. In the periphery, the hydrothermal activity is also visible along structural boundaries such as the Punte Nere, Forgia Vecchia, and Palizzi crater rims and at the base of the cone, on the southern side of the edifice, along a fault attributed to the NW main tectonic trend of the island. Inside the Punte Nere crater, the ERT sections show an electrical resistive body that we interpret as an intrusion or a dome. This magmatic body is reconstructed in 3D using the available ERT profiles. Its shape and position, with respect to the Pietre Cotte crater fault, allows replacing this structure in the chronology of the development of the volcano. It corresponds to a late phase of activity of the Punte Nere edifice. Considering the position of the SP, soil CO2 flux, and temperature maxima and the repartition of conductive zones related to hydrothermal circulation with respect to the main structural features, La Fossa cone could be considered as a relevant example of the strong influence of preexisting structures on hydrothermal fluid circulation at the scale of a volcanic edifice.
    Description: Published
    Description: 231-245
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: partially_open
    Keywords: electrical resistivity ; self-potential ; soil CO2 degassing ; temperature ; fluid circulation ; hydrothermal system ; structural boundary ; Vulcano ; La Fossa cone ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 03. Hydrosphere::03.03. Physical::03.03.02. General circulation ; 04. Solid Earth::04.01. Earth Interior::04.01.01. Composition and state ; 04. Solid Earth::04.02. Exploration geophysics::04.02.07. Instruments and techniques ; 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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  • 7
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    Nitrogen Isotopes in Volcanic Fluids of Different Geodynamic Settings (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Nitrogen isotopes , N2/36Ar and 3He/4He were measured in volcanic fluids within different geodynamic settings. Subduction zones are represented by Aeolian archipelago, Mexican volcanic belt and Hellenic arc, spreading zones – by Socorro island in Mexico and Iceland and hot spots by Iceland and Islands of Cabo Verde. The δ15N values, corrected for air contamination of volcanic fluids, discharged from Vulcano Island (Italy), highlighted the presence of heavy nitrogen (around +4.3 ±0.5‰). Similar 15N values (around +5‰), have been measured for the fluids collected in the Jalisco Block, that is a geologically and tectonically complex forearc zone of the northwestern Mexico [1]. Positive values (15N around +3‰) have been also measured in the volcanic fluids discharged from Nysiros island located in the Ellenic Arc characterized by subduction processes. All uncorrected data for the Socorro island are in the range of -1 to -2‰. The results of raw nitrogen isotope data of Iceland samples reveal more negative isotope composition (about -4.4‰). On the basis of the non-atmospheric N2 fraction (around 50%) the corrected data of 15N for Iceland are around -16‰, very close to the values proposed by [2]. In a volcanic gas sample from Fogo volcano (Cabo Verde islands) we found a very negative value: -9.9‰ and -15‰ for raw and corrected values, respectively.
    Description: Geochimica et Cosmochimica Acta
    Description: Published
    Description: Davos, Switzerland
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: open
    Keywords: Nitrogen Isotopes ; Helium Isotopes ; Volcanic fluids ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 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 ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
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    Experimental solidification of anhydrous latitic and trachytic melts at different cooling rates: the role of nucleation kinetics (2008)
    Elsevier
    Details
    Publication Date: 2020-10-29
    Description: Two sets of cooling experiments were run at atmospheric conditions for two anhydrous starting latitic and trachytic melts: 1) five cooling rates (25, 12.5, 3, 0.5, and 0.125 °C/min) between 1300° and 800 °C, and 2) a 11 0.5 °C/min cooling rate from 1300 °C with quench temperatures at 1200°, 1100°, 1000° and 900 °C. Trachytic run-products are invariably glassy. Nucleation is also suppressed in the latitic run-products at the three highest 13 cooling rates. Conversely, in the 0.5 and 0.125 °C/min runs, latites have a crystal content of 90 vol.%. The 14 phases are: plagioclase, clinopyroxene, glass and iron-bearing oxide (in order of abundance). The variable 15 quench temperatures, investigated by coupling experiments with Pt-wire and Pt- capsule sample containers inset 2,again did not produce crystallization of trachyte, whereas latitic samples are characterized by 10 vol.% of oxides, pyroxenes and plagioclase (in order of appearance), at temperature b1000 °C. Effects of (preferential) heterogeneous nucleation on sample holders, of superheating degree, and chemical species loss during cooling are absent for both melt compositions. The difference of solidification paths between these two silicate melts can be ascribed only to their small chemical differences. In comparison with calculated equilibrium conditions all the experimental latitic and trachytic run-products revealed strong kinetic effects, interpretable in the light of the nucleation theory. The glass- forming ability (GFA) of trachyte is higher, whereas their critical cooling rate (Rc) is lower (b0.125 °C/min), in comparison to latitic melts (RcN0.5 °C/min). The experimental results carried out in this study can be applied to lava flows and domes; trachytic lavas are able to flow for longer period with respect to latitic ones in a metastable condition. Glass-rich terrestrial lavas, i.e. obsidians, can be the result of sluggish nucleation kinetics due to the relative high polymerisation of evolved silicate melts.
    Description: Published
    Description: 91-101
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: crystallization ; lava flows ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.02. Seismological data
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    Distribution of volatile organic compounds in Sicilian groundwaters analysed by head space-solid phase micro extraction coupled with gas chromatography mass spectrometry (SPME/GC/MS) (2008)
    Elsevier
    Details
    Publication Date: 2020-12-09
    Description: This work presents the results of an assessment of the existence and concentration of 13 volatile organic compounds (VOCs) in groundwaters from 14 hydrological basins in Sicily (25,710 km2). On the basis of hydrological, hydrogeochemical and geological studies, 324 sampling points were selected. All groundwater sampled were collected twice, from October to December 2004 and from February to May 2005, and were analysed to determine the concentration and spatial distribution of the VOCs in the aquifers. The need to analyze a large number of samples in a short space of time so as to obtain quantitative analyses in trace concentration levels spurred us to create a new analytical method, both simple and sensitive, based on HS-SPME/GC/MS. The concentrations of VOCs measured in industrial and intensive agricultural unconfined aquifers were greater than those found in other aquifers. Tetrachloroethylene, chloroform, trichloroethylene and 1,2-dichloropropane were the most frequently detected VOCs. However, they exceeded the guideline values proposed by the EU in only three aquifers located near to industrial and intense agricultural areas.
    Description: Published
    Description: 3563-3577
    Description: 4.4. Scenari e mitigazione del rischio ambientale
    Description: JCR Journal
    Description: reserved
    Keywords: groundwater pollution ; VOCs ; aliphatic compounds ; groundwater monitoring ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
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    Volumetric observations during paroxysmal eruptions at Mount Etna: pressurized drainage of a shallow chamber or pulsed supply? (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The October 17 to November 5, 1999, eruption of Mount Etna’s Bocca Nuova crater emplaced a V15U106 m3 flow field. The eruption was characterized by 11 paroxysmal events during which intense Strombolian and lava fountain activity fed vigorous channelized PaPa flows at eruption rates of up to 120 m3 s31. Each paroxysm lasted between 75 and 450 min, and was separated by periods of less intense Strombolian activity and less vigorous (610 m3 s31) effusion. Ground-based, satellite- and model-derived volumetric data show that the eruption was characterized by two periods during which eruption rates and cumulative volume showed exponential decay. This is consistent with a scenario whereby the system was depressurized during the first eruptive period (October 17^23), repressurized during an October 24 pause, and then depressurized again during the second period (October 25^28). The imbalance between the erupted and supplied volumes mean that the two periods involved the collection of 1.5^5.7U106 m3 and 1.2^ 3.6U106 m3, respectively, or an increase in the time-averaged supply to 11.6^13.6 m3 s31 and 12.5^14.9 m3 s31. Two models are consistent with the observed episodic fountaining, derived volumetric trends and calculated volume imbalance: a magma collection model and a pulsed supply model. In the former case, depressurization of a shallow reservoir cause the observed volumetric trends and foam collapse at the reservoir roof powers fountaining. In the pulsing case, variations in magma flux account for pressurization^depressurization and supply the excess volume. Increases in rise rate and volatile flux, coupled with rapid exsolution during ascent, trigger fountaining. Limiting equations that define critical foam layer volumes and magma rise rates necessary for Hawaiian-style fountaining favor the latter model.
    Description: Published
    Description: 79-95
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Etna ; lava fountaining ; eruption rates ; lava channel ; foam layers ; rise rates ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.01. Earth Interior::04.01.05. Rheology ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.02. Exploration geophysics::04.02.05. Downhole, radioactivity, remote sensing, and other methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.07. Instruments and techniques ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 11
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    SKS splitting in Southern Italy: anisotropy variations in a fragmented subduction zone. (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: In this paper we present a collection of good quality shear wave splitting measurements in Southern Italy. In addition to a large amount of previous splitting measurements, we present new data from 15 teleseisms recorded from 2003 to 2006 at the 40 stations of the CAT/SCAN temporary network. These new measurements provide additional constraints on the anisotropic behaviour of the study region and better define the fast directions in the southern part of the Apulian Platform. For our analysis we have selected wellrecorded SKS phases and we have used the method of Silver and Chan to obtain the splitting parameters: the azimuth of the fast polarized shear wave (φ) and delay time (δt). Shear wave splitting results reveal the presence of a strong seismic anisotropy in the subduction system below the region. Three different geological and geodynamic regions are characterized by different anisotropic parameters. The Calabrian Arc domain has fast directions oriented NNE–SSW and the Southern Apennines domain has fast directions oriented NNW–SSE. This rotation of fast axes, following the arcuate shape of the slab, is marked by a lack of resolved measurements which occurs at the transition zone between those two domains. The third domain is identified in the Apulian Platform: here fast directions are oriented almost N–S in the northern part and NNE–SSW to ENE–WSW in the southern one. The large number of splitting parameters evaluated for events coming from different back-azimuth allows us to hypothesize the presence of a depth-dependent anisotropic structure which should be more complicated than a simple 2 layer model below the Southern Apennines and the Calabrian Arc domains and to constrain at 50 km depth the upper limit of the anisotropic layer, at least at the edge of Southern Apennines and Apulian Platform. We interpret the variability in fast directions as related to the fragmented subduction system in the mantle of this region. The trench-parallel φ observed in Calabrian Arc and in Southern Apennines has its main source in the asthenospheric flow below the slab likely due to the pressure induced by the retrograde motion of the slab itself. The pattern of φ in the Apulian Platform does not appear to be the direct result of the rollback motion of the slab, whose influence is limited to about 100 km from the slab. The anisotropy in the Apulian Platform may be related to an asthenospheric flow deflected by the complicated structure of the Adriatic microplate or may also be explained as frozen-in lithospheric anisotropy.
    Description: Published
    Description: 49-67
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: partially_open
    Keywords: Shear wave splitting ; Subduction ; Mantle flow ; Southern Italy ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.01. Earth Interior::04.01.03. Mantle and Core dynamics ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
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    Intrusion of eccentric dikes: The case of the 2001 eruption and its role in the dynamics of Mt. Etna volcano (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The 2001 eruption represents one of the most studied events both from volcanological and geophysical point of view on Mt. Etna. This eruption was a crucial event in the recent dynamic of the volcano, marking the passage from a period (March 1993 – June 2001) of moderate stability with slow, continuous flank sliding and contemporaneous summit eruptions, to a period (July 2001 to present) of dramatically increased flank deformations and flank eruptions. We show new GPS data and high precision relocation of seismicity in order to demonstrate the role of the 2001 intrusive phase in this change of the dynamic regime of the volcano. GPS data consist of two kinematic surveys carried out on 12 July, a few hours before the beginning of the seismic swarm, and on 17 July, just after the onset of eruptive activity. A picture of the spatial distribution of the sin-eruptive seismicity has been obtained using the HypoDD relocation algorithm based on the double-difference (DD) technique. Modeling of GPS measurements reveal a southward motion of the upper southern part of the volcano, driven by a NNW-SSE structure showing mainly left-lateral kinematics. Precise hypocenter location evidences an aseismic zone at about sea level, where the magma upraise was characterized by a much higher velocity and an abrupt westward shift, revealing the existence of a weakened or ductile zone. These results reveal how an intrusion of a dike can severely modify the shallow stress field, triggering significant flank failure. In 2001, the intrusion was driven by a weakened surface, which might correspond to a decollement plane of the portion of the volcano affected by flank instability, inducing an additional stress testified by GPS measurements and seismic data, which led to an acceleration of the sliding flanks.
    Description: In press
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: 4.2. TTC - Scenari e mappe di pericolosità sismica
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: 4.4. Scenari e mitigazione del rischio ambientale
    Description: JCR Journal
    Description: reserved
    Keywords: Stress release ; Dike ; Volcano-tectonics ; Flank instability ; Mount Etna ; Instrumental monitoring ; 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::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 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::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 13
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    Comparison between different methodologies for detecting Radon in soil along an active fault: the case of the Pernicana fault system, Mt. Etna (Italy) (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Three different methodologies were used to measure Radon (222Rn) in soil, based on both passive and active detection system. The first technique consisted of Solid State Nuclear Track Detectors (SSNTD), CR-39 type, and allowed integrated measurements. The second one consisted of a portable device for short time measurements. The last consisted of a continuous measurement device for extended monitoring, placed in selected sites. Soil 222Rn activity was measured together with soil Thoron (220Rn) and soil carbon dioxide (CO2) efflux, and it was compared with the content of radionuclides in the rocks. Two different soil gas horizontal transects were investigated across the Pernicana fault system (NE flank of Mount Etna), from November 2006 to April 2007. The results obtained with the three methodologies are in a general agreement with each other and reflect the tectonic settings of the investigated study area. The lowest 222Rn values were recorded just on the fault plane, and relatively higher values were recorded a few tens of meters from the fault axis on both of its sides. This pattern could be explained as a dilution effect resulting from high rates of soil CO2 efflux. Time variations of 222Rn activity were mostly linked to atmospheric influences, whereas no significant correlation with the volcanic activity was observed. In order to further investigate regional radon distributions, spot measurements were made to identify sites having high Rn emissions that could subsequently be monitored for temporal radon variations.. SSNTD measurements allow for extended-duration monitoring of a relatively large number of sites, although with some loss of temporal resolution due to their long integration time. Continuous monitoring probes are optimal for detailed time monitoring, but because of their expense, they can best be used to complement the information acquired with SSNTD in a network of monitored sites.
    Description: In press
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 4.4. Scenari e mitigazione del rischio ambientale
    Description: 4.5. Degassamento naturale
    Description: JCR Journal
    Description: reserved
    Keywords: Soil Radon and Thoron activity ; soil CO2 efflux ; Pernicana fault system ; Mount Etna ; volcano-tectonic monitoring ; 03. Hydrosphere::03.04. Chemical and biological::03.04.07. Radioactivity and isotopes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.08. Instruments and techniques ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.02. Exploration geophysics::04.02.05. Downhole, radioactivity, remote sensing, and other methods ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 14
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    Accumulation chamber measurements of methane fluxes from natural environments and landfills (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Direct measurement of present day CH4 diffuse degassing from the soil represents an effective tool to better estimate the degassing rate of individual sources and to calibrate global Earth degassing estimates. While many data exist on CH4 emissions from ecosystems, agricultural soils and landfills, few estimates of CH4 emissions from volcanic-geothermal areas have been performed. The authors report results and discuss applications of accumulation-chamber measurements of soil CH4 and CO2 flux from Solfatara of Pozzuoli (Naples), Vulcano Island and Poggio dell’Olivo (Viterbo) volcanic-geothermal areas, and the Palma Campania landfill (Naples). Volcanic-geothermal study areas are characterised by vent discharges of fluids with different CH4/CO2 ratios (from 4.7X1E-5 to 7.5X1E-5, 4.7X1E-4 and 2.5X1E-3 by weight, for Solfatara of Pozzuoli, Vulcano island, and Poggio dell’Olivo areas, respectively). Soil CH4 fluxes range from 0.003 to 48 g m-2 day-1 in the volcanic-geothermal areas and from 0.0021 to 936 g m-2 day-1 in the landfill, with high spatial variability observed in all areas. Using statistical methods different flux populations were distinguished (i.e. background soil gases and deeply derived gases) and the total gas emissions from study sites calculated. The results of this work show that CH4/CO2 ratios of deep fluids, fumarolic fluids in the case of the volcanicgeothermal environment and biogas in landfills, are roughly maintained in the gas phase diffusely degassed by the soil. Due to high spatial variability, a large number of flux measurements and appropriate statistical methods are needed to estimate total gas discharge from study areas. Furthermore, the simultaneous measurement of diffuse CH4 and CO2 fluxes represents a strong constraint for interpretative models of deep processes associated with soil degassing.
    Description: Published
    Description: 45-54
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: methane flux ; accumulation chamber ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 15
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    Paleo-environmental and volcano-tectonic evolution of the southeastern £ank of Mt. Etna during the last 225 ka inferred from the volcanic succession of the ‘Timpe’, Acireale, Sicily (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The tectonic escarpments locally known as ‘Timpe’ cut a large sector of the eastern flank of Etna, and allow an ancient volcanic succession dating back to 225 ka to be exposed. Geological and volcanological investigations carried out on this succession have allowed us to recognize relevant angular unconformities and volcanic features which are the remnants of eruptive fissures, as well as important changes in the nature, composition and magmatic affinity of the exposed volcanics. In particular, the recognition in the lower part of the succession of important and unequivocal evidence of ancient eruptive fissures led us to propose a local origin for these volcanics and to revise previous interpretations which attributed their westward-dipping to the progressive tectonic tilting of strata. These elements led us to reinterpret the main features of the volcanic activity occurring since 250 ka BP and their relationship with tectonic structures active in the eastern flank of Etna. We propose a complex paleo-environmental and volcanotectonic evolution of the southeastern flank of Mt. Etna, in which the Timpe fault system played the role of the crustal structure that allowed the rise and eruption of magmas in the above considered time span.
    Description: Published
    Description: 289-306
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Mount Etna ; tectonics ; fisssure eruptions ; columnar basalt ; fault escarpment ; xenoliths ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.07. Rock geochemistry ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 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::04.07.04. Plate boundaries, motion, and tectonics ; 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::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 16
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    On the fractal dimension of the fallout deposits: A case study of the 79 A.D. Plinian eruption at Mt. Vesuvius (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We investigated the existence of a fractal law (power law) distribution of size pyroclastic fragments erupted during the fallout phase of the 79 A.D. Plinian eruption at Mt. Vesuvius. In particular, we performed a particle size distribution analysis on 18 white and grey pumice samples collected in six sites distributed in the SW sector of Mt. Vesuvius. Our measurements show that the fragmentation of samples in the investigated range (from 32 mm to 850 μm) follows a power law, guaranteeing the scale invariance of the process. The relationship frequency-size distribution of the fragments is verified independently from the nature (i.e., pumices and lithics) and stratigraphic height of the considered samples in the pyroclastic deposit. Therefore, the fractal fragmentation theory can be indicated for evaluating the relationship between the intensity of fragmentation (fractal dimension D) and eruption energy. In this way the apparent chaotic distribution of the particles in the fallout deposits hides a self-organized complexity revealed by the retrieved power law distribution. We further remark that a key aspect of our analysis is the founded evidence that the fractal dimension of the lithics is systematically greater than that of the pumices.
    Description: Published
    Description: 288–299
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: fragmentation ; power law distribution ; fractal dimension ; scale invariant ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 17
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    SKS splitting measurements beneath Northern Apennines region: A case of oblique trench-retreat (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We present here the new observations of seismic anisotropy obtained from SKS birefringence analysis. We studied 27 teleseismic earthquakes recorded by the temporary seismic network of RETREAT project in the Northern Apennines region. For each station–event couple we calculate the anisotropic parameters (delay time and fast-polarization direction) by minimizing the energy in the transverse component. Our measurements confirm the existence of two domains. The Tuscany domain, on the south-west with respect to the Apennines, shows mostly NW–SE fast axes directions, with a rotation toward E–W direction moving toward the Tyrrhenian Sea. The Adria domain, north-east of the Apennines orogen, shows more scattered measurements, with prevailing N–S to NNE–SSW directions; also with back-azimuthal dependence. The transition between the two domains is abrupt in the nothern part of the study region but more gradual in the southern part. Measured delay times (1.8 s on average) suggest that the detected anisotropy is located principally in the asthenosphere. Beneath the Adria domain, where the presence of a double-layer structure seems consistent, a lithospheric contribution is plausible. An interpretation in terms of ongoing mantle deformation suggests a differential evolution of the trench-retreat process along the Northern Apennines orogen. The orogen-parallel anisotropy in the study region is beneath the inner part of the belt instead of beneath its crest and no orogen-normal measurements are found in the Tuscany side. Compared to the anisotropy pattern of the typical slab retreat seen in southern part of the Northern Apennines, in the northernmost one the anisotropy suggests that an oblique trench-retreat has occurred, possibly linked to Northern Apennines retreat since 5 Ma.
    Description: Published
    Description: 68-82
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: seismic anisotropy ; mantle deformation ; Northern Apennines ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes
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  • 18
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    An advanced video-based system for monitoring active volcanoes (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Video surveillance systems are consolidated techniques for monitoring eruptive phenomena in volcanic areas. Along with these systems, which use standard video cameras, people working in this field sometimes make use of infrared cameras providing useful information about the thermal evolution of eruptions. Real-time analysis of the acquired frames is required, along with image storing, to analyze and classify the activity of volcanoes. Human effort and large storing capabilities are hence required to perform monitoring tasks. In this paper we present a new strategy aimed at improving the performance of video surveillance systems in terms of human-independent image processing and storing optimization. The proposed methodology is based on real-time thermo-graphic analysis of the area considered. The analysis is performed by processing images acquired with an IR camera and extracting information about meaningful volcanic events. Two software tools were developed. The first provides information about the activity being monitored and automatically adapts the image storing rate. The second tool automatically produces useful information about the eruptive activity encompassed by a selected frame sequence. The software developed includes a suitable user interface allowing for convenient management of the acquired images and easy access to information about the volcanic activity monitored.
    Description: Published
    Description: 85-91
    Description: reserved
    Keywords: Volcano monitoring ; Image processing ; Smart storing rate ; Eruption data ; 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::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 19
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    Seismic anisotropy beneath the Northern Apennines (Italy): Mantle flow or lithosphere fabric? (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Shear-wave splitting estimates from recordings of 10 portable seismographic stations during the first year of the RETREAT seismic deployment, in combination with broadband data from the Italian national seismic network, are associated with seismic anisotropy within the upper mantle beneath the Northern Apennines. Anisotropic parameters derived from both shear-wave splitting and P travel-time residuals vary geographically and depend on event back-azimuth, reflecting complexity in the underlying mantle strain field. Variations of the splitting time delays and fast polarization seem to exclude a 2-D sublithosphere corner flow, associated with the Apennines subduction, as the main source of the inferred anisotropy. The anisotropic signal may be generated by a frozen-in fabric of the Adriatic and Tyrrhenian lithosphere domains, or by flow variations induced by episodic and fragmentary slab rollback.
    Description: Published
    Description: 157-170
    Description: JCR Journal
    Description: reserved
    Keywords: birefringence; ; Apennines ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes
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  • 20
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    Mount Etna 1993–2005: Anatomy of an evolving eruptive cycle (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Volcanism at Mount Etna (Italy) has been observed for millennia and inspired ancient mythologies as well as scientific thought through countless generations.Yetmuch of our understanding of the way this volcano works stems fromstudies of the past 20 years, and in particular from strengthened monitoring since the late 1980s. In addition, the eruptive activity of Etna has undergone significant changes during the past 13 years, and these have led to an improved understanding of the relationship between the plumbing system of the volcano and instability of its eastern to southern f lanks. Following the end of the 1991–1993 eruption, a new eruptive cycle began, which so far has produced about 0.23 km3 of lavas and pyroclastics (dense-rock equivalent). The cycle evolved frominitial recharging of the plumbing system and inf lation, followed by powerful summit eruptions and slow spreading of the eastern to southern f lanks, to a sequence of f lank eruptions accompanied by accelerated f lank displacement. Structurally, the volcanic system has become increasingly unstable during this period. Volcanological, geophysical and geochemical data allow the cause–effect and feedback relationships between magma accumulation below the volcano, f lank instability, and the shift from continuous summit activity to episodic f lank eruptions to be investigated. In this scenario, the growth of magma storage areas at a depth of 3–5 km below sea level exerts pressure against those f lank sectors prone to displacement, causing them to detach from the stable portions of the volcanic edifice. Geochemical data indicate that magma remains stored belowthe volcano, even during phases of intense eruptive activity, thus causing a net volumetric increase that is accommodated by f lank displacement. Instability can be enhanced by the forceful uprise ofmagma through the f lanks, as in 2001, when the f irst f lank eruption of the current eruptive cycle took place. Subsequent f lank eruptions in 2002–2003 and 2004– 2004, on the other hand, were, at least in part, facilitated by the opening of fractures at the head of moving f lank sector, although the eruptions were significantly dissimilar from one another. Renewed inflation of the volcano after the 2004–2005 eruption, continued displacement of the unstable f lank sector, and gradual resumption of summit activity in late-2005, demonstrate that the same feedback mechanisms continue to be active, and the Etna system remains highly unstable. The evolution of earlier eruptive cycles shows that a return to a state of relative stability is only possible once a voluminous f lank eruption effectively drains the magmatic plumbing system.
    Description: Published
    Description: 85–114
    Description: reserved
    Keywords: Mount Etna ; eruptive cycle ; volcano monitoring ; seismicity ; deformation ; geochemistry ; structural geology ; magma storage ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring
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  • 21
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    Dynamics of the eastern flank of Mt. Etna volcano (Italy) investigated by a dense GPS network (2007)
    Elsevier
    Details
    Publication Date: 2017-04-03
    Description: Mount Etna has developed at the intersection of two regional tectonic lineaments, the NNW–SSE trending Hybleo–Maltese escarpment, which separates the thick inland continental crust of the African platform from the Ionian Mesozoic oceanic crust, and the NE–SW Messina–Fiumefreddo fault that marks a rift zone between south Calabria and north-eastern Sicily, extending as far as the Mt. Etna area. All tectonic features affect, with outstanding surface features, the eastern side of the volcano. The eastern flank of the volcano is affected by a long-term motion toward ESE. In 1997, in order to increase the detail of the ground deformation pattern on the lower eastern flank of Mt. Etna, a new GPS network, the “Ionica” network, was installed on this sector of the volcano. This GPS network consists of 24 stations and covers the lower eastern flank of the volcano from the town of Catania to Taormina and from the coastline up to an altitude of about 1300 m. All the new stations consist in self-centring benchmarks; this kind of benchmark allows all station set-up errors to be avoided. Before the merging of the Ionica network to the frame of the global GPS network of Mt. Etna (in June 2001), three surveys were carried out on this network: in September 1997, August 1998 and January 2001. From the ground deformation pattern, it is possible to distinguish two different sectors, showing different characteristics of deformation. The southern part of the network shows a more uniform distribution of the vertical motion with a mean SE-ward horizontal component while the northern one shows an heterogeneous vertical motion with a ESE-ward horizontal component. Furthermore, a higher velocity is detected between 1997 and 1998, due to the additional stress induced by a shallow intrusion on the NW flank of the volcano. The model resulting from data inversions defines a wide sliding plane beneath the entire eastern flank of the volcano with a low dip angle. The expected velocity vectors fit well the observed ones, even if the measured velocities are still quite higher than expected, at lowermost stations. The vertical inclination of the velocity vectors measured during the 1998–2001 period, gradually decreases from West to East suggesting a sort of rotational movement of the south-eastern flank, interrupted by some anomalous vectors on the lower part, that show higher vertical velocities. These anomalies, being located on a wedge defined by the intersection of the main NNW–SSE and NE–SW fault systems and near the Timpe faults, are probably due to the activity of the vertical faults cutting the lower eastern flank of Mt. Etna. Stations lying on the hanging wall and on the footwall of the Timpe fault system are affected by similar horizontal displacements, meaning that these structures are moving eastwards together with the sliding flank; this evidence suggests that the Timpe faults are probably second order structures, with respect to the detachment surface. These results depict a structural framework of the eastern flank of Mt. Etna in which the low angle dislocation can be considered as a first order approximation of an actual listric plane and the current active part of the Timpe fault system is confined above the detachment surface.
    Description: Published
    Description: 357-369
    Description: reserved
    Keywords: ground deformation ; flank dynamics ; volcano–tectonics ; Etna volcano ; 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::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 22
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    Surface movements in Bologna (Po Plain — Italy) detected by multitemporal DInSAR (2007)
    Elsevier
    Details
    Publication Date: 2019-10-18
    Description: We studied the surface deformations affecting the southeastern sector of the Po Plain sedimentary basin, in particular the area of Bologna. To this aim an advanced DInSAR technique, referred to as DInSAR–SBAS (Small BAseline Subset), has been applied. This technique allows monitoring the temporal evolution of a deformation phenomenon, via the generation of mean deformation velocity maps and displacement time series from a data set of acquired SAR images. In particular, we have processed a set of SAR data acquired by the European Remote Sensing Satellite (ERS) sensors and compared the achieved results with optical levelling measurements, assumed as reference. The surface displacements detected by DInSAR SBAS from 1992 to 2000 are between 10 mm/year in the historical part of Bologna town, and up to 59 mm/year in the NE industrial and agricultural areas. Former measurements from optical levelling referred to 1897 show 2–3 mm/year vertical movements. This trend of displacement increased in the second half of the 20th century and the subsidence rate reached 60 mm/year. We compared the more recent levelling campaigns (in 1992 and late 1999) and DInSAR results from 1992 to 1999. The standard deviation of the difference between levelling data, projected onto the satellite Line Of Sight, and DInSAR results is 2 mm/year. This highlights a good agreement between the measurements provided by two different techniques. The explanation of soil movements based on interferometric results, ground data and geological observations, allowed confirming the anthropogenic cause (surface effect due to the overexploitation of the aquifers) and highlights a natural, tectonic, subsidence.
    Description: Published
    Description: 304-316
    Description: 1.10. TTC - Telerilevamento
    Description: JCR Journal
    Description: partially_open
    Keywords: InSAR ; surface deformation ; SAR interferometry ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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    Characterization of submarine ground water discharge offshore of south-eastern Sicily-SGD collaboration (2007)
    Elsevier
    Details
    Publication Date: 2022-06-07
    Description: A complex approach in characterisation of submarine groundwater discharge (SGD) off south-eastern Sicily comprising applications of radioactive and non-radioactive tracers, direct seepage measurements, geophysical surveys and a numerical modelling is presented. SGD fluxes in the Donnalucata boat basin were estimated by direct seepage measurements to be from 4 to 12 L s 1, which are comparable with the total SGD flux in the basin of 17 L s 1 obtained from radon measurements. The integrated SGD flux over the Donnalucata coast estimated on the basis of Ra isotopes was around 60 m3 s 1 per km of the coast. Spatial variations of SGD were observed in the Donnalucata boat basin, the average 222Rn activity concentration in seawater varied fromw0.1 kBq m 3 to 3.7 kBq m 3 showing an inverse relationship with salinity. The continuous monitoring carried out at the site closest to the coast has revealed an inverse relationship of 222Rn activity concentration on the tide. The 222Rn concentrations in seawater varied from 2.3 kBq m 3 during high tides to 4.8 kBq m 3 during low tides, thus confirming an influence of the tide on submarine groundwater discharge. Stable isotopes (d2H and d18O) showed that SGD samples consist up to 50% of groundwater. Geo-electrical measurements showed a spatial variability of the salt/ fresh water interface and its complex transformation in the coastal zone. The presented results imply that in the studied Donnalucata site there are at least two different sources of SGD, one superficial, represented by mixed fresh water and seawater, and the second one which originates in a deeper limestone aquifer.
    Description: Published
    Description: 81-101
    Description: JCR Journal
    Description: reserved
    Keywords: Submarine groundwater discharge ; Groundwater ; Seawater ; Radioactive and stable isotopes; ; Seepage measurement ; Geophysical survey ; Numerical modelling ; Mediterranean Sea ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes
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  • 24
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    Geochemical monitoring of thermal waters in Slovenia: relationships to seismic activity (2006)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Thermally anomalous fluids released in seismic areas in Slovenia were the subjects of geochemical monitoring. Thermal waters were surveyed from the seismically active area of Poso$cje (Bled and Zatolmin; NW Slovenia) and from Rogaska Slatina in eastern Slovenia. Continuous monitoring of geochemical parameters (radon concentration, electrical conductivity, and water temperature) was performed with discrete gas sampling for their 3He/4He ratio. The observed values were correlated with meteorological parameters (rainfall, barometric pressure and air temperature) and with seismic activity. Only a few earthquakes occurred in the vicinity of the measuring sites during the monitoring period. Nevertheless, changes in radon concentration, water temperature, electrical conductivity and helium isotopic ratio were detected at the three thermal springs in the periods preceding the earthquakes. A close correlation was also observed of both water temperature and electrical conductivity with the Earth tide, making the observations in the selected sites a promising tool for addressing the widely debated question of earthquake prediction.
    Description: Ministry of Education,Science and Sport of Slovenia
    Description: Published
    Description: 919–930
    Description: partially_open
    Keywords: Seismicity ; Thermal waters ; Geochemistry ; 03. Hydrosphere::03.02. Hydrology::03.02.02. Hydrological processes: interaction, transport, dynamics ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring
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  • 25
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    Field-based density measurements as tool to identify preeruption dome structure: set-up and first results from Unzen volcano, Japan (2006)
    Elsevier
    Details
    Publication Date: 2020-01-08
    Description: For an improvement in the quality of conduit flow and dome-related explosive eruption models, knowledge of the preeruption or precollapse density of the rocks involved is necessary. As close investigation is impossible during eruption, the best substitute comes from quantitative investigation of the eruption deposits. The porosity of volcanic rocks is of primary importance for the eruptive behaviour and, accordingly, a key-parameter for realistic models of dome stability and conduit flow. Fortunately, this physical property may be accurately determined via density measurements. We developed a robust, battery-powered device for rapid and reliable density measurements of dry rock samples in the field. The density of the samples (sealed in plastic bags at 250 mbar) is determined using the Archimedean principle. We have tested the device on the deposits of the 1990–1995 eruption of Unzen volcano, Japan. Short setup and operation times allow up to 60 measurements per day under fieldwork conditions. The rapid accumulation of correspondingly large data sets has allowed us to acquire the first statistically significant data set of clast density distribution in block-and-ash flow deposits. More than 1100 samples with a total weight of 2.2 tons were measured. The data set demonstrates that the deposits of the last eruptive episode at Unzen display a bimodal density distribution, with peaks at 2.0F0.1 and 2.3F0.1 g/cm3, corresponding to open porosity values of 20 and 8 vol.%, respectively. We use this data set to link the results of laboratory-based fragmentation experiments to field studies at recently active lava domes.
    Description: Published
    Description: 65-75
    Description: partially_open
    Keywords: field-based density measurements ; dome ; Unzen volcano ; explosive eruption ; block-and-ash flow ; fragmentation behaviour ; volcanology ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 26
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    Dynamics of magma ascent and fragmentation in trachytic versus rhyolitic eruptions (2005)
    Elsevier
    Details
    Publication Date: 2020-10-29
    Description: We have performed a parametric study on the dynamics of trachytic (alkaline) versus rhyolitic (calc-alkaline) eruptions by employing a steady, isothermal, multiphase non-equilibrium model of conduit flow and fragmentation. The employed compositions correspond to a typical rhyolite and to trachytic liquids from Phlegrean Fields eruptions, for which detailed viscosity measurements have been performed. The investigated conditions include conduit diameters in the range 30–90 m and total water contents from 2 to 6 wt%, corresponding to mass flow rates in the range 106–108 kg/s. The numerical results show that rhyolites fragment deep in the conduit and at a gas volume fraction ranging from 0.64 to 0.76, while for trachytes fragmentation is found to occur at much shallower levels and higher vesicularities (0.81–0.85). An unexpected result is that low-viscosity trachytes can be associated with lower mass flow rates with respect to more viscous rhyolites. This is due to the non-linear combined effects of viscosity and water solubility affecting the whole eruption dynamics. The lower viscosity of trachytes, together with higher water solubility, results in delayed fragmentation, or in a longer bubbly flow region within the conduit where viscous forces are dominant. Therefore, the total dissipation due to viscous forces can be higher for the less viscous trachytic magma, depending on the specific conditions and trachytic composition employed. The fragmentation conditions determined through the simulations agree with measured vesicularities in natural pumice clasts of both magma compositions. In fact, vesicularities average 0.80 in pumice from alkaline eruptions at Phlegrean Fields, while they tend to be lower in most calc-alkaline pumices. The results of numerical simulations suggest that higher vesicularities in alkaline products are related to delayed fragmentation of magmas with this composition. Despite large differences in the distribution of flow variables which occur in the deep conduit region and at fragmentation, the flow dynamics of rhyolites and trachytes in the upper conduit and at the vent can be very similar, at equal conduit size and total water content. This is consistent with similar phenomenologies of eruptions associated with the two magma types.
    Description: Published
    Description: 93-108
    Description: partially_open
    Keywords: trachytic magma ; conduit flow ; eruption dynamics and numerical simulations ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 27
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    Magma-derived gas influx and water-rock interactions in the volcanic aquifer of Mt. Vesuvius, Italy (2005)
    Elsevier
    Details
    Publication Date: 2021-06-25
    Description: We report in this paper a systematic investigation of the chemical and isotopic composition of groundwaters flowing in the volcanic aquifer of Mt. Vesuvius during its current phase of dormancy, including the first data on dissolved helium isotope composition and tritium content. The relevant results on dissolved He and C presented in this paper reveal that an extensive interaction between rising magmatic volatiles and groundwaters currently takes place at Vesuvius. Vesuvius groundwaters are dilute (mean TDS 2800 mg/L) hypothermal fluids (mean T 17.7°C) with a prevalent alkaline-bicarbonate composition. Calcium-bicarbonate groundwaters normally occur on the surrounding Campanian Plain, likely recharged from the Apennines. D and 18O data evidence an essentially meteoric origin of Vesuvius groundwaters, the contribution from either Tyrrhenian seawater or 18O-enriched thermal water appearing to be small or negligible. However, the dissolution of CO2-rich gases at depth promotes acid alteration and isochemical leaching of the permeable volcanic rocks, which explains the generally low pH and high total carbon content of waters. Attainment of chemical equilibrium between the rock and the weathering solutions is prevented by commonly low temperature (10 to 28°C) and acid-reducing conditions. The chemical and isotope (C and He) composition of dissolved gases highlights the magmatic origin of the gas phase feeding the aquifer. We show that although the pristine magmatic composition may vary upon gas ascent because of either dilution by a soil-atmospheric component or fractionation processes during interaction with the aquifer, both 13C/12C and 3He/4He measurements indicate the contribution of a magmatic component with a 13C 0‰ and R/Ra of 2.7, which is consistent with data from Vesuvius fumaroles and phenocryst melt inclusions in olivine phenocrysts. A main control of tectonics on gas ascent is revealed by data presented in this paper. For example, two areas of high CO2 release and enhanced rock leaching are recognized on the western (Torre del Greco) and southwestern (Torre Annunziata–Pompeii) flanks of Vesuvius, where important NE-SW and NW-SE tectonic structures are recognized. In contrast, waters flowing through the northern sector of the volcano are generally colder, less saline, and CO2 depleted, despite in some cases containing significant concentrations of magmaderived helium. The remarkable differences among the various sectors of the volcano are reconciled in a geochemical interpretative model, which is consistent with recent structural and geophysical evidences on the structure of Somma-Vesuvius volcanic complex.
    Description: -European Union, -Ministero dell’Universita’ e della Ricerca Scientifica e Tecnologica; -CNR–Gruppo Nazionale per la Vulcanologia.
    Description: Published
    Description: 963–981
    Description: partially_open
    Keywords: isotopes ; water chemistry ; dissolved gases ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 03. Hydrosphere::03.04. Chemical and biological::03.04.07. Radioactivity and isotopes ; 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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    Water speciation and Sr isotopic exchange during water-melt interaction: a combined NMR-TIMS study on the Cretaio Tephra (Ischia Island,south Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: In order to improve the microscopic understanding of the water-magma interaction process during explosive volcanism,volcanic glasses representative of deposits with sedimentological characteristics suggesting different water/melt ratios were studied by a combination of the nuclear magnetic resonance (NMR) and TIMS methods. The glasses were separated from pumices of two surge layers and one fallout bed of the Cretaio Tephra (Ischia Island,Italy), which is the product of an explosive eruption that occurred at Ischia in the second century BC. The 29Si CP^MAS NMR experiments indicate the occurrence of 1H^29Si dipolar couplings in glasses from the phreatomagmatic activity, suggesting the presence of hydrogen atoms in proximity of silicon atoms. This feature is not detected in the glass from the deposit of the magmatic explosion. 1H MAS NMR spectra reveal different peaks attributed to different hydrous species characterized by different motional properties. These include ‘rigid’ H2O groups isolated in the glass structure, more mobile water species and possibly structural hydroxyl groups. 1H MAS NMR spectra recorded after deuteration experiments of the glass at a temperature up to 300‡C revealed that the exchange reactions of the D2O vapor with hydrogen were limited to the most mobile water species,possibly on vesicle surfaces or in channels. The hydrogen concentration linearly correlates with the 87Sr/86Sr isotope ratio in glasses,suggesting isotopic tracer exchanges between the Sr dissolved in the water vapor and the Sr in the silicon-oxygen network during hydration. It is proposed that the uprising melt interacted with a hydrothermal system of seawater-derived fluids,characterized by relatively high Sr isotopic composition.
    Description: Published
    Description: 311-320
    Description: partially_open
    Keywords: Ischia ; Cretaio Tephra ; Water-melt interaction ; Nuclear magnetic resonance ; Sr isotopes ; 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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    Seismoacoustic measurements during the July–August 2001 eruption of Mt. Etna volcano, Italy (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: On July 18, 2001, two main eruptive vents opened on the southern flank of Mount Etna volcano (Italy) at ~2100 m and ~2550 m a.s.l., respectively. The former vent fed mild strombolian activity and lava flows, while the latter represented the main explosive vent, producing strong phreato-magmatic explosions. Explosions at this latter vent, however, shifted to a strombolian style in the following days, before switching back to phreato-magmatic activity towards the end of the eruption, which ended on August 9, 2001. On August 3, a small seismoacoustic array was deployed close to the eruptive vents. The array was composed of three stations, which recorded seismic and infrasonic waves coming from both of the eruptive vents. A further seismoacoustic station, equipped with a thermal-infrared sensor, was also installed several kilometers north of the first array. Seismic signals relating to the strombolian activity at the 2100-m vent were characterized by a strong decompression at the source. Analysis of the time delays between seismic, infrasonic and infrared event onsets also revealed that ejection velocities during explosions from both vents were subsonic. Time delays between the onset of explosive events apparent in the infrared and infrasound data indicated that the explosion source at the 2550-m vent was located 220–250 m below the crater rim. In comparison, the depth of the seismic source was estimated to be between 230 and 335 m below the rim. This converts to 120–150 and 130–235 m below the preexisting ground surface. In addition, time delays between seismic and infrasonic signals recorded for the lower (2100 m) vent also revealed a seismic source that was no more than a few tens of meters deeper than the fragmentation surface.
    Description: Published
    Description: 219-230
    Description: partially_open
    Keywords: Mt. Etna ; explosive eruptions ; arrays ; seismic ; infrasonic and thermal data ; 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::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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    Changes in fluid geochemistry and physico-chemical conditions of geothermal systems caused by magmatic input: The recent abrupt outgassing off the island of Panarea (Aeolian Islands, Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Hydrothermal systems and related vents can exhibit dramatic changes in their physico-chemical conditions over time as a response to varying activity in the feeding magmatic systems. Massive steam condensation and gas scrubbing processes of thermal fluids during their ascent and cooling cause further compositional changes that mask information regarding the conditions evolving at depth in the hydrothermal system. Here we propose a new stability diagram based on the CO2-CH4-CO-H2 concentrations in vapor, which aims at calculating the temperatures and pressures in hydrothermal reservoirs. To filter gas scrubbing effects, we have also developed a model for selective dissolution of CO2-H2S-N2-CH4-He-Ne mixtures in fresh and/or air-saturated seawater. This methodology has been applied to the recent (November 2002) crisis that affected the geothermal field off the island of Panarea (Italy), where the fluid composition and fluxes have been monitored for the past two decades. The chemical and isotopic compositions of the gases suggest that the volatile elements originate from an active magma, which feeds a boiling saline solution having temperatures of up to 350 C and containing 12 mol CO2 in vapor. The thermal fluids undergo cooling and re-equilibration processes on account of gas-water-rock interactions during their ascent along fracture networks. Furthermore, steam condensation and removal of acidic species, partial dissolution in cold air-saturated seawater and stripping of atmospheric components, affect the composition of the geothermal gases at shallow levels. The observed geochemical variations are consistent with a new input of magmatic fluids that perturbed the geothermal system and caused the unrest event. The present-state evolution shows that this dramatic input of fluids is probably over, and that the system is now tending towards steady-state conditions on a time scale of months.
    Description: Published
    Description: 3045-3059
    Description: partially_open
    Keywords: Submarine degassing ; geothermal system ; gas-water interaction ; gas geothermometry ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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  • 31
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    Gas hazard assessment in a densely inhabited area of Colli Albani Volcano (Cava dei Selci, Roma) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The northwestern flank of the Colli Albani, a Quaternary volcanic complex near Rome, is characterised by high CO2 values and Rn activities in the groundwater and by the presence of zones with strong emission of gas from the soil. The most significant of these zones is Cava dei Selci where many houses are located very near to the gas emission site. The emitted gas consists mainly of CO2 (up to 98 vol) with an appreciable content of H2S (0.8). The He and C isotopic composition indicates, as for all fluids associated with the Quaternary Roman and Tuscany volcanic provinces, the presence of an upper mantle component contaminated by crustal fluids associated with subducted sediments and carbonates. An advective CO2 flux of 37 tons/day has been estimated from the gas bubbles rising to the surface in a small drainage ditch and through a stagnant water pool, present in the rainy season in a topographically low central part of the area. A CO2 soil flux survey with an accumulation chamber, carried out in February-March 2000 over a 12 000 m2 surface with 242 measurement points, gave a total (mostly conductive) flux of 61 tons/day. CO2 soil flux values vary by four orders of magnitude over a 160-m distance and by one order of magnitude over several metres. A fixed network of 114 points over 6350 m2 has been installed in order to investigate temporal flux variations. Six surveys carried out from May 2000 to June 2001 have shown large variations of the total CO2 soil flux (8/25 tons/day). The strong emission of CO2 and H2S, which are gases denser than air, produces dangerous accumulations in low areas which have caused a series of lethal accidents to animals and one to a man. The gas hazard near the houses has been assessed by continuously monitoring the CO2 and H2S concentration in the air at 75 cm from the ground by means of two automatic stations. Certain environmental parameters (wind direction and speed; atm P, T, humidity and rainfall) were also continuously recorded. At both stations, H2S and CO2 exceeded by several times the recommended concentration thresholds. The highest CO2 and H2S values were recorded always with wind speeds less than 1.5 m/s, mostly in the night hours. Our results indicate that there is a severe gas hazard for people living near the gas emission site of Cava dei Selci, and appropriate precautionary and prevention measures have been recommended both to residents and local authorities.
    Description: - GNV funded research project Gas Hazard of Colli Albani
    Description: Published
    Description: 81^94
    Description: partially_open
    Keywords: Colli Albani ; CO2 flux ; H2S ; gas hazard ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.03. Geodesy::04.03.06. 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::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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    The aquatic geochemistry of arsenic in volcanic groundwaters from southern Italy (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: This paper discusses the abundance, speciation and mobility of As in groundwater systems from active volcanic areas in Italy. Using literature data and new additional determinations, the main geochemical processes controlling the fate of As during gas–water–rock interaction in these systems are examined. Arsenic concentrations in the fluids range from 0.1 to 6940 mg/l, with wide differences observed among the different volcanoes and within each area. The dependence of As content on water temperature, pH, redox potential and major ions is investigated. Results demonstrate that As concentrations are highest where active hydrothermal circulation takes place at shallow levels, i.e. at Vulcano Island and the Phlegrean Fields. In both areas the dissolution of As-bearing sulphides is likely to be the main source of As. Mature Cl-rich groundwaters, representative of the discharge from the deep thermal reservoirs, are typically enriched in As with respect to SO4-rich ‘‘steam heated groundwaters’’. In the HCO3 groundwaters recovered at Vesuvius and Etna, aqueous As cycling is limited by the absence of high-temperature interactions and by high-Fe content of the host rocks, resulting in oxidative As adsorption. Thermodynamic modelling suggests that reducing H2S-rich groundwaters are in equilibrium with realgar, whereas in oxidising environments over-saturation with respect to Fe oxyhydroxides is indicated. Under these oxidising conditions, As solubility decreases controlled by As co-precipitation with, or adsorption on, Fe oxy-hydroxides. Consistent with thermodynamic considerations, As mobility in the studied areas is enhanced in intermediate redox environments, where both sulphides and Fe hydroxides are unstable.
    Description: Published
    Description: 1283–1296
    Description: partially_open
    Keywords: Hydrogeochemistry ; Arsenic ; volcanic groundwaters ; speciation ; 03. Hydrosphere::03.01. General::03.01.01. Analytical and numerical modeling ; 03. Hydrosphere::03.02. Hydrology::03.02.02. Hydrological processes: interaction, transport, dynamics ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems
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  • 33
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    Birth, growth and morphologic evolution of the `Laghetto´ cinder cone during the 2001 Etna eruption (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We have undertaken detailed observations of the formation of the `Laghetto´ cinder cone, a new cone that formed during a 2-week period of intense activity in Piano del Lago, on the upper slopes of Mount Etna in summer 2001. We describe the events leading to the formation of a small graben, the formation of pit craters on the base of the graben, the onset of phreatomagmatic activity, a transition to intense Strombolian activity, and a return to phreatomagmatic activity as the eruption came to an end. We discuss the reasons for these transitions, and describe the morphological development of the cone during these events. Arcuate cracks on the southern part of the cone were related to withdrawal of magma at the end of the eruption. Other slope instabilities that developed during the eruption include the formation of small radial grain flows on the outer flanks of the cone and the collapse into the crater of part of the crater rim. Some of the failure planes we observed were first identified using a FLIR TM 695 thermal infrared camera. This is the first time that infrared thermography has been used to detect instability of volcanic structures. Results obtained during this test case demonstrate that thermal cameras are a very useful tool for studies of volcanic instability.
    Description: Published
    Description: 225-239
    Description: partially_open
    Keywords: Etna volcano ; cinder cone ; volcano instability ; thermal images ; phreatomagmatic activity ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 34
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    The buried caldera of Misti volcano, Peru, revealed by combining a self-potential survey with elliptic Fourier function analysis of topography (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: This survey proposes a new approach to identify buried caldera boundaries of a volcanic cone, combining (1) a systematic elliptic Fourier functions (EFF) analysis on the contour lines based on the external shape of the edifice with (2) self-potential (SP) measurements on volcano flanks. The methodology of this approach is to investigate the relationships between (1) vertical morphological changes inferred from EFF analysis and (2) lateral lithological transition inside the edifice inferred from SP/elevation gradients. The application of these methods on Misti volcano in southern Peru displays a very good correlation. The three main boundaries evidenced by hierarchical cluster analysis on the contour lines coincide with the two main boundaries characterised by SP signal and with a secondary SP signature related with a summit caldera. In order to explain these results showing a very good correlation between morphologic and lithologic changes as function of elevation, caldera boundaries have been suggested. The latter would be located at an average elevation of (1) 4350–4400 m, (2) 4950–5000 m, and (3) 5500– 5550 m. For the lowest boundary in elevation, the coincidence with the lateral extension of the hydrothermal system inferred from SP measurements suggests that caldera walls act as a barrier for lateral extension of hydrothermal systems. In the summit area, the highest boundary has been related with the summit caldera, inferred by a secondary SP minimum and geological evidence.
    Description: - Institut de Recherche pour le Développement (IRD) - Instituto Geofisico del Peru´ (IGP).
    Description: Published
    Description: 283– 297
    Description: partially_open
    Keywords: caldera ; elliptic Fourier functions ; geomorphology ; self-potential ; Misti volcano ; Peru ; 03. Hydrosphere::03.02. Hydrology::03.02.02. Hydrological processes: interaction, transport, dynamics ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.02. Exploration geophysics::04.02.04. Magnetic and electrical methods ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 05. General::05.02. Data dissemination::05.02.04. Hydrogeological data ; 05. General::05.05. Mathematical geophysics::05.05.99. General or miscellaneous ; 05. General::05.08. Risk::05.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 35
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    Groundwater radon measurements in the Mt. Etna area (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Radon levels were measured in 119 groundwater samples collected throughout the active volcanic area of Mt. Etna by means of a portable Lucas-type scintillation chamber. The measured activity values range from 1.8 to 52.7 Bq l 1. About 40% of the samples exceed the maximum contaminant level of 11 Bq l 1 proposed by the USEPA in 1991. The highest radon levels are measured in the eastern sector of the volcano, which is the seismically most active zone of the volcano. On the contrary the south-western sector, which is both seismically active and a site of intense magmatic degassing, display lower radon levels. This is probably due to the formation of a free gas phase (oversaturation of CO2) that strips the radon from the water. Comparison of the data gathered at Mt. Etna with those of other areas indicates that 222Rn activity in groundwater is positively correlated with both the content of parent elements in the aquifer rocks and the temperature of the geothermal systems that interacts with the sampled aquifers.
    Description: Published
    Description: 187–201
    Description: partially_open
    Keywords: Groundwater ; Radon ; Mount Etna ; Active volcanic areas ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.02. Hydrology::03.02.06. Water resources ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.07. Radioactivity and isotopes ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.08. Risk::05.08.01. Environmental risk
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  • 36
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    Fluid circulation and structural discontinuities inside Misti volcano (Peru) inferred from self-potential measurements (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: One of the seven potentially active andesite stratovolcanoes in southern Peru, Misti (5822 m), located 17 km northeast and 3.5 km above Arequipa, represents a major threat to the population (f900,000 inhabitants). Our recent geophysical and geochemical research comprises an extensive self-potential (SP) data set, an audioâ magnetotelluric (AMT) profile across the volcano and CO2 concentrations in the soil along a radial profile. The SP survey is the first of its kind in providing a complete mapping of a large andesitic stratovolcano 20 km in diameter. The SP mapping enables us to analyze the SP signature associated with a subduction-related active volcano. The general SP pattern of Misti is similar to that of most volcanoes with a hydrogeologic zone in the lower flanks and a hydrothermal zone in the upper central area. A quasi-systematic relationship exists between SP and elevation. Zones with constant SP/altitude gradients (Ce) are observed in both hydrogeologic (negative Ce) and hydrothermal (positive Ce) zones. Transition zones between the different Ce zones, which form a concentric pattern around the summit, have been interpreted in terms of lateral heterogeneities in the lithology. The highest amplitudes of SP anomalies seem to coincide with highly resistive zones. The hydrothermal system 6 km in diameter, which extends over an area much larger than the summit caldera, may be constrained by an older, concealed collapse caldera. A sealed zone has apparently developed through alteration in the hydrothermal system, blocking the migration of CO2 upward. Significant CO2 emanations are thus observed on the lower flanks but are absent above the hydrothermal zone.
    Description: - Institut de Recherche pour le Developpement (IRD) - Instituto Geofısico del Peru´ (IGP)
    Description: Published
    Description: 343-360
    Description: partially_open
    Keywords: Misti volcano ; self-potential ; audioâ magnetotelluric ; electrical resistivity ; structural discontinuity ; hydrothermal system ; Peru ; 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
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  • 37
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    A new collector for sampling volcanic aerosols (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A new apparatus, Venturi Effect System (VES), designed for sampling volcanic plumes is described and tested at Vulcano (Italy). This device, together with purified basic NH4OH solutions, supplies optimal conditions to obtain reliable Stotal/Cl/F ratios and enrichment factors for metallic trace elements (MTE). Good concordance for acid gas ratios and metal enrichment factors in both the gas phase and the related plume allows the procedure to be validated. The VES appears in Vulcano conditions as a simple, robust and easily portable apparatus that allows reliable collection of both acid gases and MTE within a single sample and the analysis with current chemical methods (High Pressure Liquid Chromatography, Inductively Coupled Plasma-Mass Spectrometry. This apparatus may be suitable for more difficult volcanoes where only the plume can be sampled.
    Description: Published
    Description: 95-103
    Description: partially_open
    Keywords: volcanic plume ; acid gases ; metallic trace elements ; sampling ; monitoring ; 03. Hydrosphere::03.02. Hydrology::03.02.02. Hydrological processes: interaction, transport, dynamics ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 38
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    Dissolved helium isotope ratios in ground-waters: a new technique based on gas–water re-equilibration and its application to Stromboli volcanic system (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Here, a new technique for the determination of dissolved He isotope ratios in ground-waters is presented. This method is based on the extraction and subsequent equilibrium of dissolved gases in an added ‘‘host’’ gas phase. Ultra pure N2 is placed in glass flasks (250 cc), containing water samples, that were hermetically sealed after their collection. After shaking in an ultrasonic bath for 10 min, an aliquot of the separated gas phase was removed from the flask for MS analysis. 3He/4He ratios are measured by using a modified double collector mass spectrometer (VG 5400-TFT). Helium and Ne concentrations are calculated by comparing the partial pressures of masses 4 and 20 of the samples with those of the air-standard measured by a quadrupole mass spectrometer (QMS;VG Quartz). Using He and Ne equilibrium partitioning coefficients, it is possible to calculate the amount of gas originally dissolved in the water. The technique was tested on both air-saturated waters (ASW) and thermal waters from Stromboli (Aeolian Islands, South Italy), the results of which confirmed good reproducibility (ffi5%) and accuracy (ffi3%) of the data. The method was then applied to three thermal water samples collected from the same volcanic area and the results compared with those of a fumarolic and a soil gas. The isotope ratios for dissolved He gave values of 4.06–4.23 Ra, which are significantly higher than those previously reported in the literature (3.0, 3.5 and 2.9 Ra) and that measured at the fumarole (3.09 Ra), suggesting a newer and higher isotopic signature for the volcanic system. The proposed method appears to be a useful tool in the determination of 3He/4He ratios in ground-water systems, especially when free gases are not available or are dangerous to collect.
    Description: Published
    Description: 665–673
    Description: partially_open
    Keywords: dissolved helium isotopes ; gas water interaction ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 39
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    Natural and anthropogenic factors affecting groundwater quality of an active volcano (Mt. Etna, Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: New geochemical data on dissolved major and minor constituents in 276 groundwater samples from Etna aquifers reveal the main processes responsible for their geochemical evolution and mineralisation. This topic is of particular interest in the light of the progressive depletion of water resources and groundwater quality in the area. Multivariate statistical analysis reveal 3 sources of solutes: (a) the leaching of the host basalt, driven by the dissolution of magmaderived CO2; (b) mixing processes with saline brines rising from the sedimentary basement below Etna; (c) contamination from agricultural and urban wastewaters. The last process, highlighted by increased concentrations of SO4,NO3, Ca, F and PO4, is more pronounced on the lower slopes of the volcanic edifice, associated with areas of high population and intensive agriculture. However, this study demonstrates that natural processes (a) and (b) are also very effective in producing highly mineralised waters, which in turn results in many constituents (B, V, Mg) exceeding maximum admissible concentrations for drinking water.
    Description: Published
    Description: 863–882
    Description: partially_open
    Keywords: Hydrogeochemistry ; water quality ; Mt. Etna ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 03. Hydrosphere::03.02. Hydrology::03.02.06. Water resources ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters
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  • 40
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    Isotopic, chemical and dissolved gas constraints on spring water from Popocatepetl volcano (Mexico): evidence of gas–water interaction between magmatic component and shallow fluids (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Geochemical research was carried out on cold and hot springs at Popocatepetl (Popo) volcano (Mexico) in 1999 to identify a possible relationship with magmatic activity. The chemical and isotopic composition of the fluids is compatible with strong gas–water interaction between deep and shallow fluids. In fact, the isotopic composition of He and dissolved carbon species is consistent with a magmatic origin. The presence of a geothermal system having a temperature of 80–1008 C was estimated on the basis of liquid geothermometers. A large amount of dissolved CO2 in the springs was also detected and associated with high CO2 degassing.
    Description: Published
    Description: 91– 108
    Description: partially_open
    Keywords: Popocatepetl volcano ; helium isotope composition ; carbon isotope composition ; dissolved gases ; gas–water interaction ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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