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  • 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques  (32)
  • 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
  • Elsevier  (30)
  • American Geophysical Union  (20)
  • Springer Nature
  • Taylor & Francis
  • 2005-2009  (50)
  • 1985-1989
  • 1980-1984
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  • 1
    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
    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
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  • 3
    Publication Date: 2017-04-04
    Description: Volcanoes deform as a consequence of the rise and storage of magma; once magma reaches a critical pressure, an eruption occurs. However, how the edifice deformation relates to its eruptive behavior is poorly known. Here, we produce a joint interpretation of spaceborne InSAR deformation measurements and volcanic activity at Mt. Etna (Italy), between 1992 and 2006. We distinguish two volcano-tectonic behaviors. Between 1993 and 2000, Etna inflated with a starting deformation rate of 1 cm yr 1 that progressively reduced with time, nearly vanishing between 1998 and 2000; moreover, low-eruptive rate summit eruptions occurred, punctuated by lava fountains. Between 2001 and 2005, Etna deflated, feeding higher-eruptive rate flank eruptions, along with large displacements of the entire East-flank. These two behaviors, we suggest, result from the higher rate of magma stored between 1993 and June 2001, which triggered the emplacement of the dike responsible for the 2001 and 2002–2003 eruptions. Our results clearly show that the joint interpretation of volcano deformation and stored magma rates may be crucial in identifying impending volcanic eruptions.
    Description: This work was partly funded by INGV and the Italian DPC and was supported by ASI, the Preview Project and CRdC-AMRA. DPC-INGV Flank project providing the funds for the publication fees.
    Description: Published
    Description: L02309
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 1.10. TTC - Telerilevamento
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: 4.5. Degassamento naturale
    Description: JCR Journal
    Description: partially_open
    Keywords: deformation ; eruptions ; Mt. Etna ; eruptive cycle ; InSAR ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.03. Geodesy::04.03.99. 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::04.04.09. Structural geology ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. 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::04.08.06. 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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  • 4
    Publication Date: 2017-04-04
    Description: We analyze a seismic sequence which occurred in 2000 along the Northern Apennines accretionary wedge (Italy). The sequence developed within the Cretaceous–Triassic limestones of the tectonic wedge, where methane-rich and oil reservoirs are stored. Ruptures mainly developed on WNW–ESE striking thrusts. The compressive stress field is consistent with that acting at regional scale in Northern Apennines. Seismic parameters indicate that fluids are involved in the seismogenic process. The amplitudes of the P and S phases and data from some stations evidence a P to S conversion within Vp/Vs=2.1 layer. The attenuation properties of crust show a higher attenuation zone located west of the epicentral cloud. Eight hundred aftershocks delineate a sub-vertical cloud of events between 7 and 14 km depth. The space–time evolution of the aftershocks is consistent with a diffusive spreading (diffusivity=1.9 m2/s) along vertically superimposed thrusts. Diffusion also controls the time evolution of the sequence. Fluid pressure is estimated to be roughly equal to the vertical, lithostatic stress. The overpressure within reservoirs develops by tectonic compaction processes. The fluids upraise along sub-vertical fractures related to the shortening of the wedge. The 2000 sequence occurred in an area that separates a thermal and deeper petroleum system from a shallower biogenic system. The divider of these systems controls the attenuation properties of the crust. The fluid–rock interaction at seismogenetic depth is related to hydrothermal processes more than to compaction. In accretionary wedges, seismicity activating superimposed thrusts may drive methane and oil upraising from the upper crust.
    Description: Published
    Description: 99-109
    Description: 3.1. Fisica dei terremoti
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: partially_open
    Keywords: seismicity ; fluids ; accretionary wedge ; thrust ; geodynamics ; Northern Apennines ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
    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
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  • 6
    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
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  • 7
    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)
    Type: Poster session
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  • 8
    Publication Date: 2017-04-03
    Description: Seismotectonic studies concern themselves with understanding the distribution of earthquakes in space, time, size and style. Therefore, the better these parameters are known, the most correct the association of any seismic event with the faulting structure that caused it will result. The use of accurate location methods is especially required when dealing with very complex areas, where several faulting systems or relatively small seismogenic structures exist. In fact, even though routinely determined epicentres are capable of revealing the rough picture of the seismicity, they are not suitable for studies of the fine structure of the causative fault, as their location uncertainties are often larger than the source dimension itself. In this work the probabilistic approach of the “Non Linear Localization” has been used to compute precise locations for earthquakes occurred in the last twenty years nearby the Saorge–Taggia line, a complex fault system situated in Western Liguria, close to the border between Italy and France. Together with the Breil– Sospel–Monaco and the Peille–Laghet faults, this line is responsible for the seismic activity of the area. The seismotectonic study is completed through a local tomographic study and the analysis of the focal mechanisms computed for an enlarged area. The results show that the seismicity associated with this fault system is confined within the first 10 km depth. Many clusters of seismic events are identified along the Saorge–Taggia line. The existence of a not previously mapped branch perpendicular to the Saorge–Taggia line is also recognized. Although its position may suggest it to be the continuation of the Breil–Sospel–Monaco fault system towards NE, our finding would rather suggest no association with the fault. The overall results confirm the complexity of the area; in particular the hypothesis that the Saorge–Taggia system may represent the eastward limit of a subalpine crustal block comprised within the Nice Arc, the named fault and a thrust front which is supposed to be located 20 km offshore find a confirm in the shallow depth of the seismic events. In addition we propose that the western limit of the block, located along the Nice arc, could be instead shifted where the Peille–Laghet fault lays.
    Description: Published
    Description: 470-479
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: High precision locations ; Focal mechanisms ; Fault geometry ; Western Liguria ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
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  • 9
    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
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  • 10
    Publication Date: 2017-04-04
    Description: New estimates on the Quaternary slip rate of the active transform margin of North Anatolia are provided. We investigated the area struck by a Mw 7.1 earthquake on the 12th of November 1999 that ruptured the Düzce Fault segment of the North Anatolian Fault. In order to analyze the spectacular tectonically driven cumulative landforms and the drainage pattern settings, we carried out a 1:25,000-scale geological and geomorphological mapping along the fault trace. We reconstruct and describe, as offset geomorphic markers, right-hand stream deflections and fluvial terraces inset into alluvial fan deposits. Radiocarbon dating indicates that ∼100 m stream deflections were built up by the last ∼7000 yrs of fault activity. Conversely, two documented and correlated Late Pleistocene fluvial terraces are horizontally offset by ∼300 and ∼900 m, respectively. These were dated by means of Optically Stimulated Luminescence (OSL) to ∼21 ka BP and 60 ka BP. Assuming a constant rate of deformation for the Düzce Fault, ages and related offsets translate to consistent slip rates that yield an average slip rate of 15.0±3.2 mm/yr for the last 60 ka. Thus, the Düzce Fault importantly contributes to the North Anatolian margin deformation, suggesting a present-day partitioning of displacement rates with the Mudurnu Fault to the south and confirming its important role in the seismic hazard of the area.
    Description: Published
    Description: 538-554
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: Tectonic geomorphology ; Geomorphic markers ; Slip rate ; Strike-slip ; 1999 Düzce earthquake ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
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  • 11
    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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
    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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 13
    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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 14
    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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 15
    Publication Date: 2017-04-04
    Description: Repeated phenomena of flank instability accompanied the 28 December 2002 to 21 July 2003 eruption of Stromboli volcano. The major episodes were two tsunamigenic landslides on 30 December 2002, 2 d after the volcano unrest. After 30 December, sliding processes remodeled the area affected by slope instability.We propose analyses of 565 sliding episodes taking place from December 2002 to February 2003.We try to shed light on their main seismic features and links with the ongoing seismic and volcanic activity using variogram analysis as well. A characterization of the seismic signals in the time and frequency domains is presented for 185 sliding episodes. Their frequency content is between 1 Hz and 7 Hz. On the basis of the dominant peaks and shape of the spectrum, we identify three subclasses of signals, one of which has significant energy below 2 Hz. Low-frequency signatures were also found in the seismic records of the landslides of 30 December, which affected the aerial and submarine northwestern flank of the volcano. Accordingly, we surmise that spectral analysis might provide evidence of sliding phenomena with submarine runouts.We find no evidence of sliding processes induced by earthquakes. Additionally, a negative statistical correlation between sliding episodes and explosion quakes is highlighted by variogram analysis. Variograms indicate a persistent behavior, memory, of the flank instability from 5 to 10 d.We interpret the climax in the occurrence rate of the sliding processes between 24 and 29 January 2003 as the result of favorable conditions to slope instability due to the emplacement of NW-SE aligned, dike-fed vents located near the scarp of the landslide area. Afterward, the stabilizing effect of the lava flows over the northwestern flank of the volcano limited erosive phenomena to the unstable, loose slope not covered by lava.
    Description: This work was supported financially by Istituto Nazionale di Geofisica e Vulcanologia and Dipartimento per la Protezione Civile, project INGV-DPC V4/02.
    Description: Published
    Description: Q04022
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: rockfalls ; seismicity ; volcanoes ; volcano collapses ; Stromboli ; 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::04.08. 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 ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 16
    Publication Date: 2017-04-04
    Description: We report the first measurements of volcanic gases with an unmanned aerial vehicle (UAV). The data were collected at La Fossa crater, Vulcano, Italy, during April 2007, with a helicopter UAV of 3 kg payload, carrying an ultraviolet spectrometer for remotely sensing the SO2 flux (8.5 Mg d 1), and an infrared spectrometer, and electrochemical sensor assembly for measuring the plume CO2/SO2 ratio; by multiplying these data we compute a CO2 flux of 170 Mg d 1. Given the deeper exsolution of carbon dioxide from magma, and its lower solubility in hydro-thermal systems, relative to SO2, the ability to remotely measure CO2 fluxes is significant, with promise to provide more profound geochemical insights, and earlier eruption forecasts, than possible with SO2 fluxes alone: the most ubiquitous current source of remotely sensed volcanic gas data.
    Description: Published
    Description: L06303
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Plume measurements ; carbon dioxide fluxes ; 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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  • 17
    Publication Date: 2017-04-04
    Description: It has been shown that the initial portion of P and S wave signals can provide information about the final earthquake magnitude in a wide magnitude range. This observation opens the perspective for the real-time determination of source parameters. In this paper we describe a probabilistic evolutionary approach for the real-time magnitude estimation which can have a potential use in earthquake early warning. The technique is based on empirical prediction laws correlating the low-frequency peak ground displacement measured in a few seconds after the P and/or S phase arrival and the final event magnitude. The evidence for such a correlation has been found through the analysis of 256 shallow crustal events in the magnitude range Mjma 4–7.1 located over the entire Japanese archipelago. The peak displacement measured in a 2-s window from the first P phase arrival correlates with magnitude in the range M = [4–6.5]. While a possible saturation effect above M ’ 6.5 is observed, it is less evident in an enlarged window of 4 s. The scaling of S peaks with magnitude is instead also observed at smaller time lapses (i.e., 1 s) after the first S arrival. The different scaling of P and S peaks with magnitude when measured in a 2-s window is explained in terms of different imaged rupture surface by the early portion of the body wave signals. We developed a technique to estimate the probability density function (PDF) of magnitude, at each time step after the event origin. The predicted magnitude value corresponds to the maximum of PDF, while its uncertainty is given by the 95% confidence bound. The method has been applied to the 2007 (Mjma = 6.9) Noto Hanto and 1995 (Mjma = 7.3) Kobe earthquakes. The results of this study can be summarized as follows: (1) The probabilistic algorithm founded on the predictive model of peak displacement versus final magnitude is able to provide a fast and robust estimation of the final magnitude. (2) The information available after a few seconds from the first detection of the P phase at the network can be used to predict the peak ground motion at a given regional target with uncertainties which are comparable to those derived from the attenuation law. (3) The near-source S phase data can be used jointly with P data for regional early warning purposes, thus increasing the accuracy and reliability of magnitude estimation.
    Description: Published
    Description: B12302
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: reserved
    Keywords: Bayesian approach ; P and S wave ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 18
    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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 19
    Publication Date: 2017-04-04
    Description: The 2002–2003 Etna eruption is studied through earthquake distributions and surface fracturing. In September 2002, earthquake-induced surface rupture (sinistral offset 0.48 m) occurred along the E-W striking Pernicana Fault (PF), on the NE flank. In late October, a flank eruption accompanied further ( 0.77 m) surface rupturing, reaching a total sinistral offset of 1.25 m; the deformation then propagated for 18 km eastwards to the coastline (sinistral offset 0.03 m) and southwards, along the NW-SE striking Timpe (dextral offset 0.04 m) and, later, Trecastagni faults (dextral offset 0.035 m). Seismicity (〈4 km bsl) on the E flank accompanied surface fracturing: fault plane solutions indicate an overall ESEWNWextension direction, consistent with ESE slip of the E flank also revealed by ground fractures. A three-stage model of flank slip is proposed: inception (September earthquake), climax (accelerated slip and eruption) and propagation (E and S migration of the deformation).
    Description: Published
    Description: 2286
    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: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: volcano seismology ; surface fracturing ; flank slip ; eruption ; Etna ; 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::04.04. 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::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk ; 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::04.08.03. 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::04.08.08. 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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  • 20
    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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  • 21
    Publication Date: 2017-04-04
    Description: Two-dimensional cross sections of the sulphur dioxide (SO2) distribution in the volcanic gas plume of Mt. Etna were reconstructed using tomographic techniques. The data for these projections were generated by a network of five automated scanning spectrometers, positioned on the flanks of the volcano. These measure slant-column amounts of SO2 at 105 different angles, every four minutes. Stable wind conditions allow the plume to be monitored on 82% of days. A time-series of plume cross sections was computed, revealing the potential of this method to track variations in plume position and structure on timescales of minutes to hours, a result of potential importance for air traffic and civil defence in case of eruption, when copious amounts of fine ash can be transported.
    Description: Published
    Description: L17811
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: tomography ; SO2 ; DOAS ; 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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  • 22
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    American Geophysical Union
    Publication Date: 2017-04-04
    Description: From inspection of a large set of Japanese events, we investigate the scaling of the early radiated energy, inferred from the squared velocity integral (IV2) with the final magnitude of the event. We found that the energy can only discriminate whether the event has a magnitude larger or smaller than 5.8, and in the latter case it can allow for realtime magnitude estimation. However, by normalizing IV2 for the rupture area, the initial slip scales with the magnitude between 4 〈 M 〈 7 following the expected scaling laws. We show that the ratio between the squared peak displacement and IV2 is a proxy for the slip following the same scaling but it can be directly derived from the data, without any assumption on the rupture area. The scaling relationship between initial slip and magnitude can be used for early warning applications, when integrated in a probabilistic, evolutionary approach. Citation: Festa, G., A. Zollo, and M. Lancieri (2008), Earthquake magnitude estimation from early radiated energy, Geophys. Res. Lett., 35, L22307, doi:10.1029/ 2008GL035576.
    Description: Published
    Description: L22307
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: reserved
    Keywords: Early Warning ; Rupture initiation ; Seimic Source ; Magnitude estimation ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 23
    Publication Date: 2017-04-04
    Description: We attempt to reconcile current understanding of the earthquake energy balance with recent estimates of fracture energy from seismological investigations and surface energy from geological observations. The complex structure of real fault zones suggests that earthquakes in such fault structures are dominated by scale-dependent processes.We present a model for an inelastic fault zone of finite thickness embedded in an elastic crust represented at a macroscopic scale by a mathematical plane of zero thickness. The constitutive properties of the fault zone are governed by physical processes controlling gouge and damage evolution at meso- and micro-scale. However, in order to model and interpret seismological observations, we represent dynamic fault weakening at the macroscopic scale in terms of traction evolution as a function of slip and other internal variables defining a phenomenological friction or contact law on the virtual mathematical plane. This contact law is designed to capture the main features of dynamic fault weakening during earthquake rupture. In this study we assume that total shear traction is friction and corresponds to shear resistance of the whole fault zone.We show that seismological observations, depending on finite and limited wavelength and frequency bandwidth, can only provide an estimate of breakdown stress drop and breakdown work (a more general definition of seismological fracture energy) representing a lower bound of the total intrinsic power of dissipation on the fault zone. We emphasize that geological estimates of surface energy can be compared with seismological estimates of breakdown work only if they are representative of the same macroscopic scale. In this case, it emerges that, contrary to surface energy, seismological breakdown work represents a non-negligible contribution to the earthquake energy budget.
    Description: Published
    Description: 123-131
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: partially_open
    Keywords: earthquake mechanics ; dynamic fault weakening ; fracture energy ; fault friction ; earthquake energy budget ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 24
    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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  • 25
    Publication Date: 2017-04-04
    Description: Soil temperature and total dissolved gas pressure(TDGP) data were recorded by two continuous monitoring stations on the volcano of Stromboli (Italy) between March and October 2006. During this period several TDGP and soil temperature anomalies, unrelated to external causes and characterized by a similar shape and occurrence time, were recorded. These anomalies were interpreted as transients due to changes in the degassing regime of the volcano,which was in turn related to changes in the partition ratio of the volcanic fluidsbetweenthe conduitandthe soil. In thesame period Stromboli experienced an anomalous phase of volcanic and tectonic activity. The close correlation found between volcano-tectonic activity and variations in anomalousmonitored parameters suggests that their continuous monitoring may be a useful tool for the surveillance of volcanic activity on the island.
    Description: Published
    Description: L08301
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Dissolved gases ; Soil temperature ; Total dissolved gas pressure ; Volcano monitoring ; 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::05.02.01. Geochemical data
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  • 26
    Publication Date: 2017-04-04
    Description: We model the spatial and temporal evolution of seismicity during the 1997 Umbria-Marche seismic sequence in terms of subsequent failures promoted by fluid flow. The diffusion process of pore-pressure relaxation is represented as a pressure perturbation generated by coseismic stress changes and propagating through a fluid saturated medium. The values of isotropic diffusivity range between 22 and 90 m /s. The calculated value of anisotropic diffusivity (Daniso = 250 m /s) is largest along the average strike (N140) direction of activated faults. Our results suggest that the observed spatio-temporal migration of seismicity is consistent with fluid flow.
    Description: Published
    Description: L10311
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Diffusivity ; fluid flow ; Umbria-Marce ; normal fautling ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
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  • 27
    Publication Date: 2017-04-04
    Description: We investigate background seismic activity of the Abruzzo region, a 5000 km2 area located within the Central Apennines of Italy, where in the past 600 years at least 5 large earthquakes (I=XI – X) have occurred. Between April 2003 and September 2004, a dense temporary seismic network composed of 30 digital three-component seismic stations recorded 850 earthquakes with 0.9〈ML〈3.7. We present earthquake locations and focal mechanisms obtained by standard procedures and an optimized velocity model computed with a search technique based on genetic algorithms. The seismicity occurs at a low and constant rate of ~2.6 e-04 events/day*km2 and is sparsely distributed within the first 15 km of the crust. Minor increases in the seismicity rate are related to the occurrence of small and localised seismic sequences that occur at the tip of major active normal faults along secondary structures. We observe that during the 16 months of study period, the Fucino fault system responsible for the 1915 Fucino earthquake (MS=7.0), and the major normal faults of the area, did not produce significant seismic activity. Fault plane solutions evaluated using P-wave polarity data show the predominance of normal faulting mechanisms (~55%) with NE-trending direction of extension coherent with the regional stress field active in this sector of the Apennines. Around 27% of the focal solutions have pure strike-slip mechanisms and the rest shows transtensional faulting mechanisms that mainly characterise the kinematics of the secondary structures activated by the small sequences. We hypothesize that the largest known NW-trending normal faults are presently locked and we propose that in the case of activation, the secondary structures located at their tips may act as transfer faults accommodating a minor part of the extensional deformation with strike-slip motion.
    Description: Published
    Description: 80-92
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: background seismicity ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
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  • 28
    Publication Date: 2017-04-04
    Description: This work highlights how surface geological data can integrate and complete a fault characterization including its seismogenic depth. We investigated the area struck by the November, 1999, Mw 7.1 earthquake that ruptured the Düzce segment of the North Anatolian Fault Zone (NAFZ) after the August, 1999, Mw 7.4 Izmit earthquake. To explore the persistency or evolution of the active fault setting at the surface, we compared detailed coseismic surface expressions with the long-term morphology and structural architecture of the Düzce zone. We identified a simple 1999 coseismic fault trace (CFT) and an older complex fault system (RFS) involving a wider zone of deformation. Two different parts of the Düzce segment were recognized. A western section presents a staircase trajectory of the coseismic fault trace that reactivated part of the older fault system. An eastern section presents a straight coseismic fault trace that cross-cuts the older and complex fault system. The western Düzce fault segment splays out from the Izmit counterpart of the NAFZ, forming a releasing fault junction. By comparing a model of its coseismic surface deformation field with the long-term morphology, we observed that the present topography of this western section results from the NAFZ activity by repeating coseismic deformations like those in 1999. The mechanical interaction in the release fault junction produces local transtension across the western Düzce fault and justifies its stable complexity. It does not evolve into a straight trace. The surface boundary between the Düzce fault sections also separates at depth two fault sections: one with low slip to the west, and another with a big asperity to the east. Thus, the Izmit/Düzce interaction (1) may produce an unfavorable setting for a build-up of asperities in the western Düzce segment and (2) could delay the propagation of the Izmit rupture along the Düzce segment that nucleates mainshocks only on its eastern section. In other words, the arrangement of the fault junction may permanently control how the two sections of the Düzce fault behave and rupture.
    Description: This research is supported by the European Commission Project Relief: Large earthquake faulting and implications for seismic hazard assessment in Europe: The Izmit-Düzce earthquake sequence of 1999, Turkey, Mw 7.4, 7.1, EVG1-CT-2002-00069.
    Description: Published
    Description: 185–203
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: partially_open
    Keywords: coseismic ruptures ; tectonic geomorphology ; slip distribution ; releasing fault junction ; dislocation model ; 1999 Düzce earthquake ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
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  • 29
    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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  • 30
    Publication Date: 2017-04-04
    Description: New estimates on the Quaternary slip rate of the active transform margin of North Anatolia are provided. We investigated the area struck by the 12th November 1999, Mw 7.1 earthquake, that ruptured the Düzce fault segment of the North Anatolian Fault. In order to analyze the spectacular tectonically driven cumulative landforms and the drainage pattern settings, we carried out a 1:25,000-scale geological and geomorphological mapping along the fault trace. We reconstruct and describe, as offset geomorphic markers, right-hand stream deflections and fluvial terraces inset into alluvial fan deposits. Radiocarbon dating indicates that ~100 m stream deflections were built up by the last ~7000 yrs of fault activity. Conversely, two documented and correlated Late Pleistocene fluvial terraces are horizontally offset by ~300 and ~900 m, respectively. These were dated by means of Optically Stimulated Luminescence (OSL) to ~21 ka BP and 60 ka BP. Assuming a constant rate of deformation for the Düzce Fault, ages and related offsets translate to consistent slip-rates that yield an average slip-rate of 15.0 ± 3.2 mm/yr for the last 60 ka. Thus, the Düzce Fault importantly contributes to the North Anatolian margin deformation, suggesting a present-day partitioning of displacement rates with the Mudurnu fault to the south and confirming its important role in the seismic hazard of the area.
    Description: This research is supported by the European Commission Project “Relief”: Large earthquake faulting and implications for seismic hazard assessment in Europe: The Izmit-Düzce earthquake sequence of 1999, Turkey, Mw 7.4, 7.1, EVG1-CT-2002-00069.
    Description: Published
    Description: in press
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: partially_open
    Keywords: Tectonic geomorphology ; Geomorphic markers ; Slip rate ; Strike-slip ; 1999 Düzce earthquake ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
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  • 31
    Publication Date: 2017-04-04
    Description: An application of light detection and ranging (lidar) intensity for the identification and mapping of different lava flows from the Mount Etna (Italy) active volcano is described. In September 2004 an airborne lidar survey was flown over summit sectors of Mount Etna. The information derived from lidar intensity values was used to compare the lava flows with respect to their age of emplacement. Analyzed lava flows vary in age between those dating prior to A.D. 1610 and those active during the survey (2004–2005 eruptions). The target-emitter distance, as well as surface roughness and texture at the lidar footprint scale, is the main parameter controlling the intensity response of lava flows. Variations in the roughness and texture of surfaces at a meter scale result from two main processes, initial lava cooling and subsequent surface weathering; both lead to variations in the original surface roughness of the flow. In summary: (1) initially, from the time of emplacement, the lidar intensity of lava flow surfaces decreases and (2) about 6 years after emplacement the lidar intensity of lava surfaces starts to increase with the age of flows. Lidar capability in terms of geometric (accuracy of ∼1 m in plan position and less than 1 m in elevation) and spectral (lidar intensity depends on surface reflection at λ = 1.064 μm) information can thus be effectively used to map lava flows and to define a relative chronology of lava emplacement.
    Description: Published
    Description: B02201
    Description: 3.6. Fisica del vulcanismo
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: JCR Journal
    Description: reserved
    Keywords: lava flows ; mapping ; lidar ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 32
    Publication Date: 2017-04-04
    Description: We study the coseismic and postseismic displacements related with the 1997 Umbria-Marche earthquake sequence by means of leveling lines along a deformed aqueduct located in the epicentral area. Comparing the 1960 and 10/1997 measurements we obtain 0.49 0.10 m of coseismic displacement distributed along 3 km across the normal fault zone. Modeling of the coseismic surface dislocation is obtained from a combination of low angle (38°) faults at depth and high angle (80°) upper fault branches. The best fit model indicates that the upper branches stop at 0.4 km below the ground surface and have 60% of slip with respect to the lower faults. The postseismic displacement measured during 1998 is 0.18 m and represents 36% of the apparent coseismic deformation. Moderate earthquakes in the Apennines and related surface deformation may thus result from curved faults that reflect the brittle-elastic properties of the uppermost crustal structures.
    Description: Data collection was made while both authors were at Istituto di Ricerca per la Tettonica Recente – CNR (GNDT Project), Roma, Italy. M. Copparoni (ASM, Foligno) and M. Raponi and S. Pacico (Studio Topografico s.n.c., Foligno) provided data about aqueduct and leveling lines. Analysis of data and modeling were done while RB was visiting EOST-IPG, Strasbourg, France. Preparation of the paper benefited from discussion with R. Armijo, S. Barba, P. Gomez and G. Valensise. A. Amato and an anonymous reviewer are thanked for their constructive remarks.
    Description: Published
    Description: 2695–2698
    Description: JCR Journal
    Description: open
    Keywords: Coseismic displacement ; postseismic displacement ; earthquake fault ; Colfiorito, Italy ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 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::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 33
    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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  • 34
    Publication Date: 2017-04-04
    Description: Sulphur speciation in volcanic gases acts as a major redox buffer, and H2S/SO2 ratios represent a valuable indicator of magmatic conditions and interactions between magmatic and hydrothermal fluids. However, measurement of H2S/SO2 even by direct sampling techniques, is not straightforward. We report here on application of a small ultraviolet spectrometer for real-time field measurement of H2S and SO2 concentrations, using open-path and extractive configurations. The device was tested at fumaroles on Solfatara and Vulcano, Italy, in November 2002. H2S concentrations of up to 220ppmm(400 ppmv) were measured directly above the Bocca Grande fumarole at Solfatara, and H2S/SO2 molar ratios of 2 and 2.4, respectively, were determined for the ‘F11’ and ‘F0’ fumaroles at Vulcano. In comparison with other optical techniques capable of multiple volcanic gas measurements, such as laser and FTIR spectroscopy, this approach is considerably simpler and cheaper, with the potential for autonomous, sustained hightime resolution operation.
    Description: Published
    Description: 1652
    Description: partially_open
    Keywords: Remote monitoring ; Plume chemistry ; sulphur species ; 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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  • 35
    Publication Date: 2017-04-04
    Description: The northern Apennines of Italy are characterized by a complex Tertiary tectonic history, where superposed compressional and extensional deformation occurred. In such regions, characterized by low active extensional strain rate, the coseismic surface ruptures are rare and often a matter of much debate resulting in a difficult connection between ‘‘geological’’ faults (i.e., faults which can be mapped at the surface) and ‘‘seismological’’ faults (i.e., faults which actually generate earthquakes). The availability of detailed geological mapping and high-resolution seismological data for the Colfiorito area, struck in 1997 by a sequence of six 5 〈 Mw 6 normal faulting earthquakes, allow us to compare and verify the existence of geometric and kinematic correspondence between the mapped geological Quaternary faults and the activated structures. In map view, the earthquakes distribution reflects the fault pattern mapped at the surface, the length of activated and mapped faults is quite similar (7–10 km), the coseismic subsided region imaged by interferometric synthetic aperture radar data, is located in the hanging wall of the mapped normal faults that bound the Quaternary basins. In section view, there is a geometric connection between mapped normal faults and the aftershock alignments used to image fault geometry at depth. Comparison of striated fault planes and aftershock focal mechanism solutions show a strong kinematic consistency. This study points out that the Quaternary tectonosedimentary evolution and the present-day geological and geomorphologic setting of the Colfiorito area can be interpreted as the result of repeated, extensional earthquakes, similar to the 1997 events, occurring on NW-SE trending normal faults. Our data also show that the main shocks of the Colfiorito sequence nucleated close to the intersections between the normal faults and the preexisting compressional/transpressional structures, which in 1997 acted as lateral barriers to rupture propagation and consequently constrained the fault size.
    Description: Published
    Description: TC1002
    Description: reserved
    Keywords: faults ; colfiorito 1997 ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
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  • 36
    Publication Date: 2017-04-04
    Description: The active tectonics at the front of the Southern Apennines and in the Adriatic foreland is characterized by E-W striking, right-lateral seismogenic faults, interpreted as reactivated inherited discontinuities. The best studied among these is the Molise-Gondola shear zone (MGsz). The interaction of these shear zones with the Apennines chain is not yet clear. To address this open question we developed a set of scaled analogue experiments, aimed at analyzing: 1) how dextral strike-slip motion along a pre-existing zone of weakness within the foreland propagates toward the surface and affects the orogenic wedge; 2) the propagation of deformation as a function of displacement; 3) any insights on the active tectonics of Southern Italy. Our results stress the primary role played by these inherited structures when reactivated, and confirm that regional E-W dextral shear zones are a plausible way of explaining the seismotectonic setting of the external areas of the Southern Apennines.
    Description: INGV, Università degli Studi di Pavia
    Description: Published
    Description: 21
    Description: open
    Keywords: Active strike-slip fault ; sandbox model ; southern Italy ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 37
    Publication Date: 2017-04-04
    Description: Normal faults within orogenic belts can be pre-, syn- or post-orogenic features. We studied the Gubbio normal fault (central Italy), which is an example of a pre-orogenic fault reactivated in a post-orogenic stage. The Gubbio Fault is a 22-km-long fault bordering a Quaternary basin and part of an active faults system in the Umbria–Marche region (Central Italy). The interpretation of a set of seismic profiles enables us to reconstruct the fault geometry in detail and to measure displacement and throw distributions along the fault strike. Seismic data indicate that the Gubbio Fault represents an example of multiple reactivation: at least a portion of the fault was active in the Miocene and only a part of the total displacement was achieved in the Quaternary. The reconstruction of the fault geometry at depth shows that the fault is characterised by listric geometry. The fault is also characterised by a bend along strike and structure contours show that this geometry is maintained at depth. As the fault is commonly addressed as presently active, the maximum fault dimensions are correlated to the maximum expected earthquake, and the presence of the fault bend is discussed as a possible barrier to seismic ruptures propagation.
    Description: Published
    Description: (2233–2249)
    Description: reserved
    Keywords: Listric normal faults ; Fault reactivation ; Seismic profiles ; Displacement distribution ; Earthquakes ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
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  • 38
    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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  • 39
    Publication Date: 2021-01-27
    Description: In this work, the control exerted by the stress axes orientation on the evolution of seismic sequences developing in compressive and extensional regimes is analysed. According to the Anderson fault theory, the vertical stress is the minimum principal stress in compressional tectonic regimes, whereas it is the maximum principal stress in extensional regimes. Using Mohr diagrams and discussing the present knowledge about the distribution of vertical and horizontal stress with depth we show that, in absence of localised fluid overpressure, such changes imply that thrust and normal faults become more unstable at shallower and greater depths, respectively. These opposite mechanical behaviours predict, in a rather isotropic body, easier rupture at shallower level in compressional regimes later propagating downward. On the contrary, a first deep rupture propagating upward is expected in extensional regimes. This is consistent with observations from major earthquakes from different areas in the world. We show that the exceptions to downward migration along thrusts occur along steeply inclined faults and probably imply localised supra-hydrostatic fluid pressures. Moreover, we show that the inversion of the meaning of the lithostatic load has consequences also for the role of topography. High topography, increasing the vertical load, should inhibit earthquake development in compressional environments and should favour it in extensional settings. Although several factors, such as geodynamic processes, local tectonic features and rock rheology, are likely to control earthquake locations, stress distribution and tectonic regime, these model predictions are consistent with seismicity distribution in Italy, central Andes and Himalaya. In these areas, large to medium compressional earthquakes occur at the low elevation borders of compressional mountain belts, whereas large extensional earthquakes occur in correspondence to maximum elevations.
    Description: ASI 2001, Cofin 2001 and GNDT fundings
    Description: Published
    Description: 195-222
    Description: partially_open
    Keywords: Seismicity migration ; thrusts ; normal faults ; aftershocks ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
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    Type: article , article
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  • 40
    Publication Date: 2021-01-05
    Description: Destructive earthquakes are rare in France yet pose a sizable seismic hazard, especially when critical infrastructures are concerned. Only a few destructive events have occurred within the instrumental period, the most important being the 11 June 1909, Lambesc (Provence) earthquake. With a magnitude estimated at 6.2 [Rothé, 1942], the event was recorded by 30 observatories and produced intensity IX effects in the epicentral area, ~30 km north of Marseille. We collected 30 seismograms, leveling data and earthquake intensities to assess the magnitude and possibly the focal mechanism of this event. Following this multidisciplinary approach, we propose a source model where all relevant parameters are constrained by at least two of the input datasets. Our reappraisal of the seismological data yielded Mw 5.8-6.1 (6.0 preferred) and Ms 6.0, consistent with the magnitude from intensity data (Me 5.8) and with constraints derived from modeling of coseismic elevation changes. Hence, we found the Lambesc earthquake to have been somewhat smaller than previously reported. Our datasets also constrain the geometry and kinematics of faulting, suggesting that the earthquake was generated by reverse-right lateral slip on a WNW-striking, steeply north-dipping fault beneath the western part of the Trévaresse fold. This result suggests that the fold, located in front of the Lubéron thrust, plays a significant role in the region’s recent tectonic evolution. The sense of slip obtained for the 1909 rupture also agrees with the regional stress field obtained from earthquake focal mechanisms and microtectonic data as well as recent GPS data.
    Description: Published
    Description: 2454
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    Keywords: Lambesc earthquake ; France ; historical seismograms ; displacement modeling ; macroseismic data ; geodetic data ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.05. Historical seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 41
    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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  • 42
    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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  • 43
    Publication Date: 2017-04-04
    Description: Volcanic gas emissions from fumaroles on the rim of La Fossa crater, Vulcano Island, Italy, were measured simultaneously using direct sampling (for H2O, CO2, total sulfur, HCl and HF), filter packs (for SO2, HCl, HF) and short-path active-mode FTIR measurements (for H2O, CO2,SO2, HCl and HF) in an intercomparison study in May 2002. The results show that Cl/F ratios were in good agreement between all three methods, and that FTIR and direct sampling determined comparable proportions of CO2 and H2O. Amounts of total S observed in direct sampling data were approximately double the amounts of SO2 measured with filter packs and FTIR. This difference could be attributed either to the fact FTIR and filter packs do not measure reduced sulfur species (e.g., H2S) or to sublimation of elemental S upon exit from the fumarole, after collection by direct sampling but before detection with FTIR and filter packs.
    Description: Published
    Description: L02610
    Description: partially_open
    Keywords: volcanic gas techniques ; gas 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
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  • 44
    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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 45
    Publication Date: 2017-04-04
    Description: A new method for extracting dissolved gases in natural waters has been developed and tested, both in the laboratory and in the field. The sampling device consists of a polytetrafluroethylene (PTFE) tube (waterproof and gas permeable) sealed at one end and connected to a glass sample holder at the other end. The device is pre-evacuated and subsequently dipped in water, where the dissolved gases permeate through the PTFE tube until the pressure inside the system reaches equilibrium. A theoretical model describing the time variation in partial gas pressure inside a sampling device has been elaborated, combining the mass balance and ‘‘Solution-Diffusion Model’’ which describes the gas permeation process through a PTFE membrane). This theoretical model was used to predict the temporal evolution of the partial pressure of each gas species in the sampling device. The model was validated by numerous laboratory tests. The method was applied to the groundwater of Vulcano Island (southern Italy). The results suggest that the new sampling device could easily extract the dissolved gases from water in order to determine their chemical and isotopic composition.
    Description: - European Social Fund.
    Description: Published
    Description: Q09005
    Description: partially_open
    Keywords: dissolved gases ; helium isotope ; PTFE membrane ; Vulcano Island ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 03. Hydrosphere::03.02. Hydrology::03.02.07. Instruments and techniques ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 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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  • 46
    Publication Date: 2017-04-04
    Description: Ground-based measurements of volcanic sulfur dioxide fluxes are important indicators of volcanic activity, with application in hazard assessment, and understanding the impacts of volcanic emissions upon the environment and climate. These data are obtained by making traverses underneath the volcanic plume a few kilometers from source with an ultraviolet spectrometer, measuring integrated SO2 concentrations across the plume’s cross section, and multiplying by the plume’s transport speed. However, plume velocities are usually derived from ground-based anemometers, located many kilometers from the traverse route and hundreds of meters below plume altitude, complicating the experimental design and introducing large flux (can be 〉100%) errors. Here we present the first report of a single instrument capable of (accurate) volcanic SO2 flux measurements. This device records integrated SO2 concentrations and plume heights during traverses. Between traverses, two in-plume SO2 time series are measured from underneath the plume with the instrument, corresponding to zenith and inclined (user-specified angle from vertical in the direction of the volcano) fields of view, respectively. The distance between the points of intersection of the two views with the plume is found on the basis of the determined plume height, and the two signals are cross-correlated to determine the lag between them, enabling accurate derivation of the wind speed. We present flux data (with errors ±12%) obtained in this way at Mt. Etna during July 2004.
    Description: Published
    Description: Q02003
    Description: partially_open
    Keywords: DOAS ; volcanic SO2 emissions. ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 47
    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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 48
    Publication Date: 2017-04-04
    Description: The performance of a newly-developed portable gas analyzer, capable of real-time measurement of CO2, SO2 and H2S concentrations in volcanic gases, was tested at La Fossa Crater, Vulcano Island. The gas analyzer was used to acquire about 3000 determinations over the fumarolic field, allowing the definition of its chemical structure and heterogeneity. Our high-resolution analysis reveals that, in December 2004, the La Fossa fumarolic field was characterized by an oxidized inner core (SO2/H2S ratios of 3), and by more reducing conditions on its northern edge (SO2/H2S ratios of 1; range: 0.2–3.3). CO2/(SO2+H2S) molar ratios averaged 35 ± 21, with overlapping compositions for rim and inner crater fumaroles. S-poor compositions (CO2/(SO2+H2S) 50) characterized the field margins, probably due to deposition of native sulfur. Based on the above data and an SO2 flux of 18 ± 3 t.d-1, we estimate CO2 and H2S output rates from the volcano of 420 ± 250 and 4 ± 2 t.d-1, respectively.
    Description: Published
    Description: L13309
    Description: partially_open
    Keywords: electrochemical sensors ; fumarolic gases ; 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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  • 49
    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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  • 50
    Publication Date: 2017-04-04
    Description: We defend the two statements of ours in Michelini and Lomax [2004] about Zhang and Thurber [2003] regarded by Thurber and Zhang as incorrect and misleading.
    Description: Published
    Description: partially_open
    Keywords: earthquake location ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
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