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  • 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics  (25)
  • 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques  (25)
  • American Geophysical Union  (46)
  • Geological Society of America  (4)
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  • 1
    facet.materialart.
    Unbekannt
    High-speed imaging of Strombolian explosions: The ejection velocity of pyroclasts (2015)
    American Geophysical Union
    Details
    Publikationsdatum: 2020-12-14
    Beschreibung: Explosive volcanic eruptions are defined as the violent ejection of gas and hot fragments from a vent in the Earth's crust. Knowledge of ejection velocity is crucial for understanding and modeling relevant physical processes of an eruption, and yet direct measurements are still a difficult task with largely variable results. Here we apply pioneering high-speed imaging to measure the ejection velocity of pyroclasts from Strombolian explosive eruptions with an unparalleled temporal resolution. Measured supersonic velocities, up to 405 m/s, are twice higher than previously reported for such eruptions. Individual Strombolian explosions include multiple, sub-second-lasting ejection pulses characterized by an exponential decay of velocity. When fitted with an empirical model from shock-tube experiments literature, this decay allows constraining the length of the pressurized gas pockets responsible for the ejection pulses. These results directly impact eruption modeling and related hazard assessment, as well as the interpretation of geophysical signals from monitoring networks.
    Beschreibung: INGV-DPC “V2” and “Paroxysm”, FIRB-MIUR “Research and Development of New Technologies for Protection and Defense of Territory from Natural Risks”, and FP7-PEOPLE-IEF-2008 – 235328 Projects
    Beschreibung: Published
    Beschreibung: L02301
    Beschreibung: 3V. Dinamiche e scenari eruttivi
    Beschreibung: JCR Journal
    Beschreibung: open
    Schlagwort(e): strombolian ; ejection velocity ; explosive eruption ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    facet.materialart.
    Unbekannt
    Volcaniclastic flow hazard zonation in the Sub-Apennine Vesuvian area using GIS and remote sensing (2015)
    Geological Society of America
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Steep slopes mantled by pyroclastic deposits are favorable areas prone to generate hazardous volcaniclastic fl ows. In Italy, such a setting is well represented in the Campania Region, where pyroclastic deposits from the explosive activity of the Neapolitan volcanoes (Ischia, Campi Flegrei, and Somma-Vesuvius) cover the Apennine range bordering the Campanian Plain. In order to provide a useful contribution to the mitigation and prevention of these calamitous natural events, this work presents a multidisciplinary approach to improve the understanding of the volcaniclastic fl ow hazard zonation in an Apennine area of 340 km2 surrounding the Somma-Vesuvius volcano. The disruption proneness index (DPI) was calculated in order to identify the drainage basins potentially prone to generate volcaniclastic fl ows. This index is obtained by combining satellite and morphometric data in a geographic information system (GIS) environment. It is calculated for 1100 drainage basins, considering the main parameters infl uencing the slope stability (slope angle, basin shape factor, curvature, relative relief, aspect, and land cover). The land cover mapping is obtained from Landsat data and airborne high-resolution images, while the morphometric parameters are derived from a digital elevation model (DEM) with a cell size of 10 m. The result is a zonation map that classifi es the drainage basins according to different degrees of proneness to generate volcaniclastic fl ows (low, moderate, high, and very high). The drainage basins falling within high and very high classes are 66%, while 28% fall in the moderate class, and the remaining 6% fall in the low proneness class.
    Beschreibung: Published
    Beschreibung: 1419–1431
    Beschreibung: 3V. Dinamiche e scenari eruttivi
    Beschreibung: 4V. Vulcani e ambiente
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): Volcaniclastic Flow, Disruption Proneness Index (DPI), Sub-Apennine Vesuvian areas, Remote Sensing, GIS ; 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::05.08. Risk::05.08.02. Hydrogeological risk
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 3
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    Unbekannt
    New insights into crustal structure, Cenozoic magmatism, CO2 degassing and seismogenesis in the southern Apennines and Irpinia region from local earthquake tomography (2015)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: We present high-resolution Vp and Vp/Vs models of the southern Apennines (Italy) computed using local earthquakes recorded from 2006 to 2011 with a graded inversion scheme that progressively resolves the crustal structure, from the large scale of the Apennines belt to the local scale of the normal-fault system. High-Vp bodies defined in the upper and mid crust under the external Apennines are interpreted as extensive mafic intrusions revealing anorogenic magmatism episodes that broadened on the Adriatic domain during Paleogene. Under the mountain belt, a low-Vp region, annular to the Neapolitan volcanic district, indicates the existence of a thermal/fluid anomaly in the mid crust, coinciding with a shallow Moho and diffuse degassing of deeply derived CO2. In the belt axial zone, low Vp/Vs gas-pressurized rock volumes under the Apulian carbonates correlate to high heat flow, strong CO2-dominated gas emissions of mantle origin and shallow carbonate reservoirs with pressurized CO2 gas caps. We hypothesize that the pressurized fluid volumes located at the base of the active fault system influence the rupture process of large normal-faulting earthquakes, like the 1980 Mw6.9 Irpinia event, and that major asperities are confined within the high-Vp Apulian carbonates. This study confirms once more that pre-existing structures of the Pliocene Apulian belt controlled the rupture propagation during the Irpinia earthquake. The main shock broke a 30 km long, NE-dipping seismogenic structure, whereas delayed ruptures (both the 20 s and the 40 s sub-events) developed on antithetic faults, reactivating thrust faults located at the eastern edge of the Apulian belt.
    Beschreibung: Published
    Beschreibung: 8283–8311
    Beschreibung: 1T. Geodinamica e interno della Terra
    Beschreibung: 2T. Tettonica attiva
    Beschreibung: 4T. Fisica dei terremoti e scenari cosismici
    Beschreibung: JCR Journal
    Beschreibung: embargoed_20150609
    Schlagwort(e): The velocity structure of the southern Apennines is determined by a multi-scale tomography ; Large Cenozoic mafic intrusions are identified in the Apulian crust ; Pressurized CO2 reservoirs identified under the axial belt can affect crustal seismicity ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 05. General::05.02. Data dissemination::05.02.02. Seismological data
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 4
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    Unbekannt
    High-speed imaging, acoustic features, and aeroacoustic computations of jet noise from Strombolian (and Vulcanian) explosions (2015)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: High-speed imaging of explosive eruptions at Stromboli (Italy), Fuego (Guatemala), and Yasur (Vanuatu) volcanoes allowed visualization of pressure waves from seconds-long explosions. From the explosion jets, waves radiate with variable geometry, timing, and apparent direction and velocity. Both the explosion jets and their wave fields are replicated well by numerical simulations of supersonic jets impulsively released from a pressurized vessel. The scaled acoustic signal from one explosion at Stromboli displays a frequency pattern with an excellent match to those from the simulated jets. We conclude that both the observed waves and the audible sound from the explosions are jet noise, i.e., the typical acoustic field radiating from high-velocity jets. Volcanic jet noise was previously quantified only in the infrasonic emissions from large, sub-Plinian to Plinian eruptions. Our combined approach allows us to define the spatial and temporal evolution of audible jet noise from supersonic jets in small-scale volcanic eruptions.
    Beschreibung: INGV-DPC “V2” and “Paroxysm,” FIRB-MIUR “Research and Development of New Technologies for Protection and Defense of Territory from Natural Risks,” and FP7-PEOPLE-IEF-2008–235328 “NEMOH” ITN projects
    Beschreibung: Published
    Beschreibung: 3096–3102
    Beschreibung: 3V. Dinamiche e scenari eruttivi
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): jet noise ; volcano acoustics ; Stromboli ; Yasur ; Fuego ; strombolian eruption ; 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)
    Materialart: article
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  • 5
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    First observations of the fumarolic gas output from a restless caldera: implications for the current period of unrest (2005-2013) at Campi Flegrei (2015)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: The fumarolic gas output has not been quantified for any of the currently deforming calderas worldwide, due to the lack of suitable gas flux sensing techniques. In view of resumption of ground uplift (since 2005) and the associated variations in gas chemistry, Campi Flegrei, in southern Italy, is one of the restless calderas where gas flux observations are especially necessary. Here we report the first ever obtained estimate of the Campi Flegrei fumarolic gas output, based on a set of MultiGAS surveys (performed in 2012 and 2013) with an ad-hoc-designed measurement setup. We estimate that the current Campi Flegrei fumarolic sulphur (S) flux is low, on the order of 1.5–2.2 tons/day, suggesting substantial scrubbing of magmatic S by the hydrothermal system. However, the fumarolic carbon dioxide (CO2) output is ∼460±160 tons/day (mean±SD), which is surprisingly high for a dormant volcano in the hydrothermal stage of activity, and results in a combined (fumaroles + soil) CO2 output of ∼1560 tons/day. Assuming magma to be the predominant source, we propose that the current CO2 output can be supplied by either (i) a large (0.6–4.6 km3), deeply stored (〉7 km) magmatic source with low CO2 contents (0.05–0.1 wt%) or (ii) by a small to medium-sized (∼0.01–0.1 km3) but CO2-rich (2 wt%) magma, possibly stored at pressures of ∼100 to 120 MPa. Independent geophysical evidence (e.g., inferred from geodetic and gravity data) is needed to distinguish between these two possibilities.
    Beschreibung: Published
    Beschreibung: 4153–4169
    Beschreibung: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): Campi Flegrei ; calderas ; gas output ; 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
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 6
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    The 2012 Ferrara seismic sequence: Regional crustal structure, earthquake sources, and seismic hazard (2015)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Inadequate seismic design codes can be dangerous, particularly when they underestimate the true hazard. In this study we use data from a sequence of moderate-sized earthquakes in northeast Italy to validate and test a regional wave propagation model which, in turn, is used to under- stand some weaknesses of the current design spectra. Our velocity model, while regionalized and somewhat ad hoc, is consistent with geophysical observations and the local geology. In the 0.02–0.1 Hz band, this model is validated by using it to calculate moment tensor solutions of 20 earth- quakes (5.6 MW 3.2) in the 2012 Ferrara, Italy, seismic sequence. The seismic spectra observed for the relatively small main shock significantly exceeded the design spectra to be used in the area for critical structures. Observations and synthetics reveal that the ground motions are dominated by long-duration surface waves, which, apparently, the design codes do not adequately anticipate. In light of our results, the present seismic hazard assessment in the entire Pianura Padana, including the city of Milan, needs to be re-evaluated. Citation: Malagnini, L., R. B. Herrmann, I. Munafò, M. Buttinelli, M. Anselmi, A. Akinci, and E. Boschi (2012), The 2012 Ferrara seismic sequence: Regional crustal structure, earthquake sources, and seismic hazard, Geophys. Res. Lett., 39, L19302, doi:10.1029/ 2012GL053214.
    Beschreibung: Published
    Beschreibung: L19302
    Beschreibung: 4T. Fisica dei terremoti e scenari cosismici
    Beschreibung: JCR Journal
    Beschreibung: open
    Schlagwort(e): earthquake sources, seismic hazard ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 7
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    Real-time measurements of the concentration and isotope composition of atmospheric and volcanic CO2 at Mount Etna (Italy) (2014)
    American Geophysical Union
    Details
    Publikationsdatum: 2020-02-24
    Beschreibung: We present unprecedented data of real-time measurements of the concentration and isotope composition of CO2 in air and in fumarole-plume gases collected in 2013 during two campaigns at Mount Etna volcano, which were made using a laser-based isotope ratio infrared spectrometer. We performed approximately 360 measurements/h, which allowed calculation of the δ13C values of volcanic CO2. The fumarole gases of Torre del Filosofo (2900mabove sea level) range from 3.24 ± 0.06‰to 3.71 ± 0.09‰, comparable to isotope ratio mass spectrometry (IRMS) measurements of discrete samples collected on the same dates. Plume gases sampled more than 1 km from the craters show a δ13C= 2.2 ± 0.4‰, in agreement with the crater fumarole gases analyzed by IRMS. Measurements performed along ~17km driving track from Catania to Mount Etna show more negative δ13C values when passing through populated centers due to anthropogenic-derived CO2 inputs (e.g., car exhaust). The reported results demonstrate that this technique may represent an important advancement for volcanic and environmental monitoring.
    Beschreibung: Published
    Beschreibung: 2382–2389
    Beschreibung: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): Real-time data of CO2 content and δ13C in atmospheric/volcanic gases ; This study opens new perspective for the community for volcanic surveillance ; 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 ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 8
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    Continental delamination and mantle dynamics drive topography extension and fl uid discharge in the Apennines (2014)
    Geological Society of America
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: The Apennines belt of Italy undergoes a northeast-trending extension at a rate of a few millimeters per year that generates moderate to large normal-faulting earthquakes. In this paper, we show that seismicity, large earthquakes, strong gas emission, and belt topography all correlate with a broad, low Vp anomaly in the uppermost mantle. We propose that a thermal/fl uid anomaly in the mantle, associated with sub-lithospheric mantle replacement after delamination of the Adria lithosphere, supports the topography of the belt and drives the extensional tectonics. The mantle anomaly is likely caused by deep fl uids coming from the dehydration of the material subducted during the Europe-Adria collision and the delamination of Adria. Beneath the belt, CO2-rich fl uids are accumulated and occasionally discharged during large normal faulting earthquakes. After the replacement of sub-lithospheric mantle, the temperature at the base of the crust increases causing crustal stretching, anatexis, and strong degassing.
    Beschreibung: Published
    Beschreibung: 715-718
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: 2.4. TTC - Laboratori di geochimica dei fluidi
    Beschreibung: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): mantle anomaly ; Continental delamination ; the Apennines ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 9
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    The coupling between very long period seismic events, volcanic tremor, and degassing rates at Mount Etna volcano (2014)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: From December 2005 to January 2006, an anomalous degassing episode was observed at Mount Etna, well-correlated with an increase in volcanic tremor, and in the almost complete absence of eruptive activity. In the same period, more than 10,000 very long period (VLP) events were detected. Through moment tensor inversion analyses of the VLP pulses, we obtained quantitative estimates of the volumetric variations associated with these events. This allowed a quantitative investigation of the relationship between VLP seismic activity, volcanic tremor, and gas emission rate at Mount Etna. We found a statistically significant positive correlation between SO2 gas flux and volcanic tremor, suggesting that tremor amplitude can be used as a first-order proxy for the background degassing activity of the volcano. VLP volumetric changes and SO2 gas flux are correlated only for the last part of our observations, following a slight change in the VLP source depth. We calculate that the gas associated with VLP signal genesis contributed less than 5% of the total gas emission. The existence of a linear correlation between VLP and degassing activities indicates a general relationship between these two processes. The effectiveness of such coupling appears to depend upon the particular location of the VLP source, suggesting that conduit geometry might play a significant role in the VLP-generating process. These results are the first report on Mount Etna of a quantitative relationship between the amounts of gas emissions directly estimated through instrumental flux measurements and the quantities of gas mass inferred in the VLP source inversion.
    Beschreibung: Published
    Beschreibung: 4910-4921
    Beschreibung: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): Very Long Period seismicity ; UV scanners network ; Etna Volcano ; volcano monitoring ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 10
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    A study on the reproducibility of counting vesicles in volcanic rocks (2012)
    Geological Society of America
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Vesicle size distributions in two and three dimensions of two samples were independently measured by three different researchers to investigate whether or not such measurements are reproducible. Additionally, two different software programs were used to measure the three-dimensional vesicle size distributions: the 3D Object Counter plugin for ImageJ and Blob3D. Manual thresholding by each of the authors produced similar results for both samples using both programs; however, use of the automatic, maximum entropy technique for thresholding produced measurably different results because it did not discriminate between vesicles and plagioclase crystals in one case and between vesicles and some cracks in another. Use of asymmetric erosion and dilation processes on the images is shown to affect the vesicle size distribution, but it does not have a significant effect on the power-law exponent that describes intermediate-sized vesicles or on the vesicle number density in these samples. However, such a technique is not recommended.
    Beschreibung: Published
    Beschreibung: 70-78
    Beschreibung: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Volcanic rocks ; vesicle counting ; reproducibility ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 11
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    The mechanics of lubricated faults: Insights from 3-D numerical models (2012)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-03
    Beschreibung: The weakening mechanisms occurring during an earthquake failure are of prominent importance in determining the resulting energy release and the seismic waves excitation. In this paper we consider the fully dynamic response of a seismogenic structure where lubrication processes take place. In particular, we numerically model the spontaneous propagation of a 3-D rupture in a fault zone where the frictional resistance is controlled by the properties of a low viscosity slurry, formed by gouge particles and fluids. This model allows for the description of the fault motion in the extreme case of vanishing effective normal stress, by considering a viscous fault response and therefore without the need to invoke, in the framework of Coulomb friction, the generation of the tensile mode of fracture. We explore the effects of the parameters controlling the resulting governing law for such a lubricated fault; the viscosity of the slurry, the roughness of the fault surfaces and the thickness of the slurry film. Our results indicate that lubricated faults produce a nearly complete stress drop (i.e., a very low residual friction coefficient; mu ~ 0.01), a high fracture energy density (E_G ~ few 10s of MJ/m^2) and significant slip velocities (vpeak ~ few 10s of m/s). The resulting values of the equivalent characteristic slip-weakening distance (d_0_eq = 0.1–0.8 m, depending on the adopted parameters) are compatible with the seismological inferences. Moreover, in the framework of our model we found that supershear ruptures are highly favored. In the case of enlarging gap height we can have the healing of slip or even the inhibition of the rupture. Quantitative comparisons with different weakening mechanisms previously proposed in the literature, such as the exponential weakening and the frictional melting, are also discussed.
    Beschreibung: Published
    Beschreibung: B05304
    Beschreibung: 3.1. Fisica dei terremoti
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): governing models ; theoretical seismology ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 12
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    How do volcanic rift zones relate to flank instability? Evidence from collapsing rifts at Etna (2012)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Volcanic rift zones, characterized by repeated dike emplacements, are expected to delimit the upper portion of unstable flanks at basaltic edifices. We use nearly two decades of InSAR observations excluding wintertime acquisitions, to analyze the relationships between rift zones, dike emplacement and flank instability at Etna. The results highlight a general eastward shift of the volcano summit, including the northeast and south rifts. This steadystate eastward movement (1-2 cm/yr) is interrupted or even reversed during transient dike injections. Detailed analysis of the northeast rift shows that only during phases of dike injection, as in 2002, does the rift transiently becomes the upper border of the unstable flank. The flank's steady-state eastward movement is inferred to result from the interplay between magmatic activity, asymmetric topographic unbuttressing, and east-dipping detachment geometry at its base. This study documents the first evidence of steady-state volcano rift instability interrupted by transient dike injection at basaltic edifices.
    Beschreibung: Partially funded by INGV and the Italian DPC (DPC-INGV project V4 “Flank”). ERS and ENVISAT SAR data were provided by ESA through the Cat-1 project no. 4532 and the GEO Supersite initiative. The DEM was obtained from the SRTM archive. ERS-1/2 orbits are courtesy of the TU-Delft, The Netherlands. SAR data processing has been done at IREACNR, partially carried out under contract “Volcanic Risk System (SRV)” funded by the Italian Space Agency (ASI).
    Beschreibung: Published
    Beschreibung: L20311
    Beschreibung: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 1.10. TTC - Telerilevamento
    Beschreibung: 3.2. Tettonica attiva
    Beschreibung: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: 4.3. TTC - Scenari di pericolosità vulcanica
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): flank instability ; rift zones ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 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::04.04. 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::04.07. 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::05.08. Risk::05.08.99. General or miscellaneous
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 13
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    Source mechanism of long-period events recorded by a high-density seismic network during the 2008 eruption on Mount Etna (2012)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: One hundred twenty-nine long-period (LP) events, divided into two families of similar events, were recorded by the 50 stations deployed on Mount Etna in the second half of June 2008. During this period lava was flowing from a lateral fracture after a summit Strombolian eruption. In order to understand the mechanisms of these events, we perform moment tensor inversions. Inversions are initially kept unconstrained to estimate the most likely mechanism. Numerical tests show that unconstrained inversion leads to reliable moment tensor solutions because of the close proximity of numerous stations to the source positions. However, single forces cannot be accurately determined as they are very sensitive to uncertainties in the velocity model. Constrained inversions for a crack, a pipe or an explosion then allow us to accurately determine the structural orientations of the source mechanisms. Both numerical tests and LP event inversions emphasise the importance of using stations located as close as possible to the source. Inversions for both families show mechanisms with a strong volumetric component. These events are most likely generated by cracks striking SW–NE for both families and dipping 70° SE (family 1) and 50° NW (family 2). For family 1 events, the crack geometry is nearly orthogonal to the dikelike structure along which events are located, while for family 2 the location gave two pipelike bodies that belong to the same plane as the crack mechanism. The orientations of the cracks are consistent with local tectonics, which shows a SW–NE weakness direction. The LP events appear to be a response to the lava fountain occurring on 10 May 2008 as opposed to the flank lava flow.
    Beschreibung: Published
    Beschreibung: B01304
    Beschreibung: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Beschreibung: 3.1. Fisica dei terremoti
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Etna Volcano ; long-period events ; source mechanism ; location ; plumbing systems ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 14
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    Complexity of theMw6.3 2009 L’Aquila (central Italy) earthquake: 2. Broadband strong motion modeling (2012)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Near-fault strong-ground motions (0.1–10 Hz) recorded during the Mw 6.3 2009 L’Aquila earthquake exhibit great spatial variability. Modeling the observed seismograms allows linking distinct features of the observed wavefield to particular source and propagation effects and provides insights on strong motion complexity from this moderate magnitude event. We utilize a hybrid integral-composite approach based on a k-square kinematic rupture model, combining low-frequency coherent and high-frequency incoherent source radiation and providing omega-squared source spectral decay. Several source model features, proven to be stable by means of an uncertainty analysis in the preceding low-frequency (〈0.2 Hz) multiple finite-extent source inversion (Paper 1), were constrained. Synthetic Green’s functions are calculated in a 1D-layered crustal model including 1D soil profiles to account for site-specific response (where available). The results show that although the local site effects improve the modeling, the spatial broadband ground-motion variability is to large extent controlled by the rupture kinematics. The modeling thus confirms and further constraints the source model features, including the position and slip amount of the two main asperities, the largest asperity time delay and the rupture velocity distribution on the fault. Furthermore, we demonstrate that the crossover frequency dividing the coherent and incoherent wavefield, often considered independent on the station position, has to be variable in order to adequately reproduce both near and far station recordings. This suggests that the incoherency of the radiated wavefield is controlled by the wave-propagation phenomena and/or the initial updip rupture propagation was very smooth (coherent) up to relatively high frequencies (〉2 Hz)
    Beschreibung: Published
    Beschreibung: B0438
    Beschreibung: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): broad band modeling, source complexity, aquila earthquake ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 15
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    Tephra sedimentation during the 2010 Eyjafjallajökull eruption (Iceland) from deposit, radar, and satellite observations (2012)
    American Geophysical Union
    Details
    Publikationsdatum: 2023-01-16
    Beschreibung: The April–May 2010 eruption of the Eyjafjallajökull volcano (Iceland) was characterized by a nearly continuous injection of tephra into the atmosphere that affected various economic sectors in Iceland and caused a global interruption of air traffic. Eruptive activity during 4–8 May 2010 was characterized based on short-duration physical parameters in order to capture transient eruptive behavior of a long-lasting eruption (i.e., total grain-size distribution, erupted mass, and mass eruption rate averaged over 30 min activity). The resulting 30 min total grain-size distribution based on both ground and Meteosat Second Generation-Spinning Enhanced Visible and Infrared Imager (MSG-SEVIRI) satellite measurements is characterized by Mdphi of about 2 and a fine-ash content of about 30 wt %. The accumulation rate varied by 2 orders of magnitude with an exponential decay away from the vent, whereas Mdphi shows a linear increase until about 18 km from the vent, reaching a plateau of about 4.5 between 20 and 56 km. The associated mass eruption rate is between 0.6 and 1.2 × 105 kg s−1. In situ sampling showed how fine ash mainly fell as aggregates of various typologies. About 5 to 9 wt % of the erupted mass remained in the cloud up to 1000 km from the vent, suggesting that nearly half of the ash 〉7 settled as aggregates within the first 60 km. Particle sphericity and shape factor varied between 0.4 and 1 with no clear correlation to the size and distance from vent. Our experiments also demonstrate how satellite retrievals and Doppler radar grain-size detection can provide a real-time description of the source term but for a limited particle-size range.
    Beschreibung: Published
    Beschreibung: B12202
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): MSG-SEVIRI, PLUDIX ; particle aggregation ; settling velocity ; tephra deposits ; weak plumes ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 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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  • 16
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    Quantitative analysis of X-ray microtomography images of geomaterials: Application to volcanic rocks (2011)
    Geological Society of America
    Details
    Publikationsdatum: 2021-01-27
    Beschreibung: X-ray computed microtomography is an excellent tool for the three-dimensional analysis of rock microstructure. Digital images are acquired, visualized, and processed to identify and measure several discrete features and constituents of rock samples, by means of mathematical algorithms and computational methods. In this paper, we present digital images of volcanic rocks collected with X-ray computed microtomography techniques and studied by means of a software library, called Pore3D, custom-implemented at the Elettra Synchrotron Light Laboratory of Trieste (Italy). Using the Pore3D software, we analyzed the fabrics and we quantified the characteristics of the main constituents (vesicles, crystals, and glassy matrix) of four different types of pyroclasts: frothy pumice, tube pumice, scoria, and “crystalline” scoria. We identified the distinctive features of these different types of volcanic rocks. The frothy pumices show vesicles that coalesce in isotropic aggregates, especially toward the sample interior, while the scoriae have a low porosity and an abundance of isolated vesicles. In the “crystalline” scoria sample most of the vesicle separation is due to the presence of crystals of different types, while the tube pumice shows an anisotropic distribution of vesicles and crystals at the microscale, as also observed at the scale of the hand sample. Quantitative analysis and textural information may supply an additional tool to investigate the eruptive processes and the origin of volcanic rocks.
    Beschreibung: Published
    Beschreibung: 793-804
    Beschreibung: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): X-ray tomography ; 3D imaging ; volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 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
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    A relation between lava discharge rate, thermal insulation, and flow area set using lidar data (2011)
    American Geophysical Union
    Details
    Publikationsdatum: 2012-02-03
    Beschreibung: A simple linear relation can be used to link time averaged discharge rate (TADR) and lava flow area (A). The relation applies to given insulation conditions, as described by the characteristic flow surface temperature (Te), and will vary from case-to-case depending on rheological and topographic influences on flow spreading. Most flows have insulation conditions that change through time, modifying the relationship between TADR and area as insulation conditions evolve. Using lidar data we can define TADR, the flow area that the discharge feeds and Te, allowing generation of a case-specific relation to convert satellite-data-derived flow areas to TADR. For Etna's 2006 lava flow field we obtain a relation whereby TADR = 5.6 × 10−6 A for well insulated conditions (Te = 100°C) and TADR = 1.5 × 10−4 A for poorly insulated conditions (Te = 600°C).
    Beschreibung: Published
    Beschreibung: L20308
    Beschreibung: 1.10. TTC - Telerilevamento
    Beschreibung: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): lava flow ; discharge rate ; area ; surface temperature ; lidar ; Etna. ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 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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  • 18
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    Intermediate-focus earthquakes under South Shetland Islands (Antarctica) (2011)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Intermediate-focus seismicity (50〈H〈100km) related to the underplating zone of the South Shetland plate have been recorded at a small aperture seismic array set up in Deception Island, Antarctica.
    Beschreibung: Published
    Beschreibung: 531-534
    Beschreibung: 3.1. Fisica dei terremoti
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Deep earthquakes ; Antarctica ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 19
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    Source Mechanism of Long Period events recorded by a high density seismic network during the 2008 eruption on Mt Etna (2011)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 129 Long Period (LP) events, divided in two families were recorded by 50 stations deployed on Mount Etna within an eruptive context in the second half of June 2008. In order to understand the mechanisms of these events, we perform moment tensor inversion. Numerical tests show that unconstrained inversion leads to reliable moment tensor solutions because of the close proximity of numerous stations to the source positions. However, single forces cannot be accurately determined as they are very sensitive to uncertainities in the velocity model. These tests emphasize the importance of using stations located as close as possible to the source in the inversion of LP events. Inversion of LP signals is initially unconstrained, in order to estimate the most likely mechanism. Constrained inversions then allow us to accurately determine the structural orientations of the mechanisms. Inversions for both families show mechanisms with strong volumetric components. These events are generated by cracks striking SW-NE for both families and dipping 70± SE (fam. 1) and 50± NW (fam. 2). The geometries of the cracks are different from the structures obtained by the location of these events. The orientation of the cracks is consistent with the local tectonic context on Mount Etna. The LP events seem to be a response to the lava fountain occuring on the 10th of May, 2008.
    Beschreibung: In press
    Beschreibung: (38)
    Beschreibung: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Beschreibung: 3.1. Fisica dei terremoti
    Beschreibung: JCR Journal
    Beschreibung: open
    Schlagwort(e): Long-Period events ; earthquake source mechanism ; Etna Volcano ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 20
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    Kinematics and source zone properties of the 2004 Sumatra-Andaman earthquake and tsunami: Nonlinear joint inversion of tide gauge, satellite altimetry, and GPS data (2011)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: We (re)analyzed the source of the 26 December 2004 Sumatra-Andaman earthquake and tsunami through a nonlinear joint inversion of an inhomogeneous data set made up of tide gauges, satellite altimetry, and far-field GPS recordings. The purpose is twofold: (1) the retrieval of the main kinematics rupture parameters (slip, rake, and rupture velocity) and (2) the inference of the rigidity of the source zone. We independently estimate the slip from tsunami data and the seismic moment from geodetic data to derive the rigidity. Our results confirm that the source of the 2004 Sumatra-Andaman earthquake has a complex geometry, constituted by three main slip patches, with slip peaking at ~30 m in the southern part of the source. The rake direction rotates counterclockwise at the northern part of the source, according to the direction of convergence along the trench. The rupture velocity is higher in the deeper than in the shallower part of the source, consistent with the expected increase of rigidity with depth. It is also lower in the northern part, consistent with known variations of the incoming plate properties and shear velocity. Our model features a rigidity (20–30 GPa) that is lower than the preliminary reference Earth model (PREM) average for the seismogenic volume. The source rigidity is one of the factors controlling the tsunami genesis: for a given seismic moment, the lower the rigidity, the higher the induced seafloor displacement. The general consistence between our source model and previous studies supports the effectiveness of our approach to the joint inversion of geodetic and tsunami data for the rigidity estimation.
    Beschreibung: Published
    Beschreibung: B02304
    Beschreibung: 3.1. Fisica dei terremoti
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Source process ; Sumatra ; Tsunami ; Joint Inversion ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 21
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    Kinematics and Source Zone Properties of the 2004 Sumatra-Andaman Earthquake and Tsunami: Nonlinear Joint Inversion of Tide-Gage, Satellite Altimetry and GPS data (2010)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: We (re)analyzed the source of the 26 December 2004 Sumatra-Andaman earthquake and tsunami through a nonlinear joint inversion of an in-homogeneous dataset made up of tide-gages, satellite altimetry, and far-field GPS recordings. The purpose is two-fold: (1) the retrieval of the main kinematics rupture parameters (slip, rake, rupture velocity); (2) the inference of the rigidity of the source zone. We independently estimate the slip from tsunami data and the seismic moment from geodetic data, so to derive the rigidity. Our results confirm that the source of the 2004 Sumatra-Andaman earthquake has a complex geometry, constituted by three main slip patches, with slip peaking at ~30 meters in the Southern part of the source. The rake direction rotates counter-clockwise at North, according to the direction of convergence along the trench. The rupture velocity is higher in the deeper than in the shallower part of the source, consistently with the expected increase of rigidity with depth. It is also lower in the Northern part, consistently with known variations of the incoming plate properties and shear velocity. Our model features a rigidity (20-30 GPa), that is lower than PREM average for the seismogenic volume [Dziewonski and Anderson, 1981]. The source rigidity is one of the factors controlling the tsunamigenesis: for a given seismic moment, the lower the rigidity, the higher the induced seafloor displacement. The general consistence between our source model and previous studies supports the effectiveness of our approach to the joint inversion of geodetic and tsunami data for the rigidity estimation.
    Beschreibung: In press
    Beschreibung: 3.1. Fisica dei terremoti
    Beschreibung: JCR Journal
    Beschreibung: open
    Schlagwort(e): Source process ; Sumatra ; Tsunami ; joint inversion ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 22
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    On the transient behavior of frictional melt during seismic slip (2010)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: In a recent work on the problem of sliding surfaces under the presence of frictional melt (applying in particular to earthquake fault dynamics), we derived from first principles an expression for the steady state friction compatible with experimental observations. Building on the expressions of heat and mass balance obtained in the above study for this particular case of Stefan problem (phase transition with a migrating boundary) we propose here an extension providing the full time-dependent solution (including the weakening transient after pervasive melting has started, the effect of eventual steps in velocity and the final decelerating phase). A system of coupled equations is derived and solved numerically. The resulting transient friction and wear evolution yield a satisfactory fit (1) with experiments performed under variable sliding velocities (0.9-2 m/s) and different normal stresses (0.5-20 MPa) for various rock types and (2) with estimates of slip weakening obtained from observations on ancient seismogenic faults that host pseudotachylite (solidified melt). The model allows to extrapolate the experimentally observed frictional behavior to large normal stresses representative of the seismogenic Earth crust (up to 200 MPa), high slip rates (up to 9 m/s) and cases where melt extrusion is negligible. Though weakening distance and peak stress vary widely, the net breakdown energy appears to be essentially independent of either slip velocity and normal stress. In addition, the response to earthquake-like slip can be simulated, showing a rapid friction recovery when slip rate drops. We discuss the properties of energy dissipation, transient duration, velocity weakening, restrengthening in the decelerating final slip phase and the implications for earthquake source dynamics.
    Beschreibung: S.N. and G.D.T. were supported by a European Research Council Starting Grant Project (acronym USEMS) and by a Progetti di Eccellenza Fondazione Cassa di Risparmio di Padova e Rovigo. We are grateful to Nick Beeler (and to an anonymous referee) for their constructive reviews and their help to improve the clarity of the manuscript.
    Beschreibung: Published
    Beschreibung: B10301
    Beschreibung: 3.1. Fisica dei terremoti
    Beschreibung: JCR Journal
    Beschreibung: open
    Schlagwort(e): Friction ; Melt ; Earthquake dynamics ; fault mechanics ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 23
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    Energy radiation from intermediate to large magnitude earthquakes: implications for dynamic fault weakening (2010)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: The amount of energy radiated from an earthquake can be measured using recent methods based on earthquake coda signals and spectral ratios. Such methods are not altered by either site or directivity effects, with the advantage of a greatly improved accuracy. Several studies of earthquake sequences based on the above measurements showed evidence of a breakdown in self-similarity in the moment to energy relation. Radiated energy can be also used as a gauge to estimate the average dynamic stress drop on the fault. Here we compute the dynamic stress drop, infer the co-seismic friction and estimate the co-seismic heating resulting from the frictional work during events from different main shock-aftershock earthquake sequences. We relate the dynamic friction to the maximum temperature rise estimated on the faults for each earthquake. Our results are strongly indicative that a thermally triggered dynamic frictional weakening is present, responsible for the breakdown in self-similarity. These observations from seismic data are compatible with recent laboratory evidence of thermal weakening in rock friction under seismic slip-rates, associated to various physical processes such as melting, decarbonation or dehydration.
    Beschreibung: Kevin Mayeda was supported under Weston Geophysical subcontract No. GC19762NGD and AFRL contract No. FA8718-06-C-0024. Work by L. Malagnini was performed under the auspices of the Dipartimento della Protezione Civile, under contract S3 – INGV-DPC (2007-2009), project: “Valutazione rapida dei parametri e degli effetti dei forti terremoti in Italia e nel Mediterraneo”.
    Beschreibung: Published
    Beschreibung: B06319
    Beschreibung: 3.1. Fisica dei terremoti
    Beschreibung: JCR Journal
    Beschreibung: open
    Schlagwort(e): earthquake radiation ; coda ; friction ; self-similarity ; dynamic weakening ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 24
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    Topographic control on lava flow paths at Mount Etna, Italy: Implications for hazard assessment (2010)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Assessment of the hazard from lava flow inundation at the active volcano of Mount Etna, Italy, was performed by calculating the probability of lava flow inundation at each position on the volcano. A probability distribution for the formation of new vents was calculated using geological and volcanological data from past eruptions. The simulated lava flows from these vents were emplaced using a maximum expected flow length derived from geological data on previous lava flows. Simulations were run using DOWNFLOW, a digital-elevation-model-based model designed to predict lava flow paths. Different eruptive scenarios were simulated by varying the elevation and probability distribution of eruptive points. Inundation maps show that the city of Catania and the coastal zone may only be impacted by flows erupted from low-altitude vents (〈1500 m elevation) and that flank eruptions at elevations 〉2000 m preferentially inundate the northeast and southern sectors of the volcano as well as the Valle del Bove. Eruptions occurring in the summit area (〉3000 m elevation) pose no threat to the local population. Discrepancies between the results of simple, hydrological models and those of the DOWNFLOW model show that hydrological approaches are inappropriate when dealing with Etnean lava flows. Because hydrological approaches are not designed to reproduce the full complexity of lava flow spreading, they underestimate the catchment basins when the fluid has a complex rheology.
    Beschreibung: Published
    Beschreibung: F01019
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Beschreibung: 4.3. TTC - Scenari di pericolosità vulcanica
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): volcanic hazard ; lava flow ; Mount Etna ; 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
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  • 25
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    Patterns in the recent 2007–2008 activity of Mount Etna volcano investigated by integrated geophysical and geochemical observations (2010)
    American Geophysical Union
    Details
    Publikationsdatum: 2012-02-03
    Beschreibung: An edited version of this paper was published by AGU. Copyright (2010) American Geophysical Union
    Beschreibung: Seismic, deformation, and volcanic gas observations offer independent and complementary information on the activity state and dynamics of quiescent and eruptive volcanoes and thus all contribute to volcanic risk assessment. In spite of their wide use, there have been only a few efforts to systematically integrate and compare the results of these different monitoring techniques. Here we combine seismic (volcanic tremor and long‐period seismicity), deformation (GPS), and geochemical (volcanic gas plume CO2/SO2 ratios) measurements in an attempt to interpret trends in the recent (2007–2008) activity of Etna volcano. We show that each eruptive episode occurring at the Southeast Crater (SEC) was preceded by a cyclic phase of increase‐decrease of plume CO2/SO2 ratios and by inflation of the volcano’s summit captured by the GPS network. These observations are interpreted as reflecting the persistent supply of CO2‐rich gas bubbles (and eventually more primitive magmas) to a shallow (depth of 1–2.8 km asl) magma storage zone below the volcano’s central craters (CCs). Overpressuring of the resident magma stored in the upper CCs’ conduit triggers further magma ascent and finally eruption at SEC, a process which we capture as an abrupt increase in tremor amplitude, an upward (〉2800 m asl) and eastward migration of the source location of seismic tremor, and a rapid contraction of the volcano’s summit. Resumption of volcanic activity at SEC was also systematically anticipated by declining plume CO2/SO2 ratios, consistent with magma degassing being diverted from the central conduit area (toward SEC).
    Beschreibung: Published
    Beschreibung: Q09008
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Beschreibung: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): volcano monitoring ; Mt. Etna volcano ; geochemistry and geophysics ; volcanic tremor ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 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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  • 26
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    Focal mechanisms for sub‐crustal earthquakes in the Gulf of Cadiz from a dense OBS deployment (2010)
    American Geophysical Union
    Details
    Publikationsdatum: 2012-02-03
    Beschreibung: An edited version of this paper was published by AGU. Copyright (2010) American Geophysical Union.
    Beschreibung: An eleven‐month deployment of 25 ocean bottom seismometers provides an unprecedented opportunity to study low‐magnitude local earthquakes in the complex transpressive plate boundary setting of the Gulf of Cadiz, known for the 1755 Lisbon earthquake and tsunami. 36 relocated earthquakes (ML 2.2 to 4.8) concentrate at 40– 60 km depth, near the base of the seismogenic layer in ∼140 Ma old oceanic mantle lithosphere, and roughly align along two perpendicular, NNE‐SSW and WNWESE striking structures. First motion focal mechanisms indicate compressive stress for the cluster close to the northern Horseshoe fault termination which trends perpendicular to plate convergence. Focal mechanisms for the second cluster near the southern termination of the Horseshoe fault indicate a strike‐slip regime, providing evidence for present‐day activity of a dextral shear zone proposed to represent the Eurasia‐Africa plate contact. We hypothesize that regional tectonics is characterized by slip partitioning.
    Beschreibung: Published
    Beschreibung: L18309
    Beschreibung: 3.1. Fisica dei terremoti
    Beschreibung: 3.2. Tettonica attiva
    Beschreibung: 3.3. Geodinamica e struttura dell'interno della Terra
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): oceanic lithospheric mantle ; focal mechanisms ; stress tensor inversion ; Gulf of Cadiz ; ocean bottom seismometer ; 1755 Lisbon earthquake ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 27
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    Short‐term and long‐term tremor migration patterns of the Cascadia 2004 tremor and slow slip episode using small aperture seismic arrays (2010)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: An edited version of this paper was published by AGU. Copyright (2010) American Geophysical Union.
    Beschreibung: Tectonic tremor has been recorded at many subduction zones, including the Nankai, Cascadia, Mexican, and Alaskan subduction zones. This study, the first to use small aperture seismic arrays to track tremor, deployed three small aperture seismic arrays along the Cascadia subduction zone during a tremor and slow slip episode in July 2004. The tremor was active during virtually all (up to 99%) minutes of the analyzed tremor episode using 5 min sample windows. Individual wave phases were tracked across the arrays and used to derive slowness vectors. These were compared with slowness vectors computed from a standard layered Earth model to derive tremor locations. Locations were stable within a volume roughly 250 km2 in epicenter and 20 km in depth for hours to days before moving to a new volume. The migration between volumes was not smooth, and the movement of the sources within the volume followed no specific pattern. Overall migration speeds along the strike of the subduction zone were between 5 and 15 km/d; smaller scale migration speeds between volumes reached speeds up to 2 km/min. Uncertainties in the best locations were 5 km in epicenter and 10 km in depth. For this data set and processing methodology, tremor does not locate predominately on the primary subduction interface. Our favored model for the generation of tectonic tremor signals is that the tremor is triggered by stress and fluid pressure changes caused by slow slip and is composed, at least in part, of low‐frequency earthquakes broadly distributed in location
    Beschreibung: Published
    Beschreibung: B00A24
    Beschreibung: 3.2. Tettonica attiva
    Beschreibung: 3.3. Geodinamica e struttura dell'interno della Terra
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): tremor migration ; Cascadia 2004 ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 28
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    Detachment depth revealed by rollover deformation: An integrated approach at Mount Etna (2010)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Flank instability is common at volcanoes, even though the subsurface structures, including the depth to a detachment fault, remain poorly constrained. Here, we use a multidisciplinary approach, applicable to most volcanoes, to evaluate the detachment depth of the unstable NE flank of Mt. Etna. InSAR observations of Mount Etna during 1995–2008 show a trapdoor subsidence of the upper NE flank, with a maximum deformation against the NE Rift. The trapdoor tilt was highest in magnitude in 2002–2004, contemporaneous with the maximum rates of eastward slip along the east flank. We explain this deformation as due to a general eastward displacement of the flank, activating a rotational detachment and forming a rollover anticline, the head of which is against the NE Rift. Established 2D rollover construction models, constrained by morphological and structural data, suggest that the east‐dipping detachment below the upper NE flank lies at around 4 km below the surface. This depth is consistent with seismicity that clusters above 2–3 km below sea level. Therefore, the episodically unstable NE flank lies above an east‐dipping rotational detachment confined by the NE Rift and Pernicana Fault. Our approach, which combines short‐term (InSAR) and long‐term (geological) observations, constrains the 3D geometry and kinematics of part of the unstable flank of Etna and may be applicable and effective to understand the deeper structure of volcanoes undergoing flank instability or unrest.
    Beschreibung: This work was partially funded by INGV and the DPC‐INGV project “Flank”, and partially by the ASI (SRV project).
    Beschreibung: Published
    Beschreibung: L16304
    Beschreibung: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 1.10. TTC - Telerilevamento
    Beschreibung: 3.2. Tettonica attiva
    Beschreibung: 4.3. TTC - Scenari di pericolosità vulcanica
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): flank instability ; fault ; InSAR ; Etna ; rollover ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 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::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 04. Solid Earth::04.06. 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::04.07.02. 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::05.08. Risk::05.08.99. General or miscellaneous
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 29
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    Deformation and eruptions at Mt. Etna (Italy): A lesson from 15 years of observations (2009)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 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.
    Beschreibung: 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.
    Beschreibung: Published
    Beschreibung: L02309
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 1.10. TTC - Telerilevamento
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: 4.3. TTC - Scenari di pericolosità vulcanica
    Beschreibung: 4.5. Degassamento naturale
    Beschreibung: JCR Journal
    Beschreibung: partially_open
    Schlagwort(e): 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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  • 30
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    Earthquake-generated tsunamis in the Mediterranean Sea: scenarios of potential threats to Southern Italy (2008)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: We calculated the impact on Southern Italy of a large set of tsunamis resulting from earthquakes generated by major fault zones of the Mediterranean Sea. Our approach merges updated knowledge on the regional tectonic setting and scenario-like calculations of expected tsunami impact. We selected three potential source zones located at short, intermediate and large distance from our target coastlines: the Southern Tyrrhenian thrust belt; the Tell-Atlas thrust belt; and the western Hellenic Arc. For each zone we determined a Maximum Credible Earthquake and described the geometry, kinematics and size of its associated Typical Fault. We then let the Typical Fault float along strike of its parent source zone and simulated all tsunamis it could trigger. Simulations are based on the solution of the nonlinear shallow water equations through a finite-difference technique. For each run we calculated the wave fields at desired simulation times and the maximum water elevation field, then produced travel-time maps and maximum wave-height profiles along the target coastlines. The results show a highly variable impact for tsunamis generated by the different source zones. For example, a large Hellenic Arc earthquake will produce a much higher tsunami wave (up to 5 m) than those of the other two source zones (up to 1.5 m). This implies that tsunami scenarios for Mediterranean Sea countries must necessarily be computed at the scale of the entire basin. Our work represents a pilot study for constructing a basin-wide tsunami scenario database to be used for tsunami hazard assessment and early warning.
    Beschreibung: Italian Civil Defense; Project “Development of new technologies for the protection of the Italian territory from natural hazards” funded by the Italian Ministry of University and Research
    Beschreibung: Published
    Beschreibung: B01301
    Beschreibung: 3.1. Fisica dei terremoti
    Beschreibung: 3.2. Tettonica attiva
    Beschreibung: 4.2. TTC - Scenari e mappe di pericolosità sismica
    Beschreibung: JCR Journal
    Beschreibung: partially_open
    Schlagwort(e): Tsunamis ; Mediterranean Sea ; Seismotectonics ; 03. Hydrosphere::03.01. General::03.01.01. Analytical and numerical modeling ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 31
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    Stress interaction effect on the occurrence probability of characteristic earthquakes in Central Apennines (2008)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: In this study, we compute the effect of stress change due to previous historical earthquakes on the probability of occurrence of future earthquakes on neighboring faults. Following a methodology developed in the last decade, we start from the estimate of the probability of occurrence in the next 50 years for a characteristic earthquake on known seismogenic structures, based on a time-dependent renewal model. Then a physical model for the Coulomb stress change caused by previous earthquakes on these structures is applied. The influence of this stress change on the occurrence rate of characteristic earthquakes is computed, taking into account both permanent (clock advance) and temporary (rate-and-state) perturbations. We apply this method to the computation of earthquake hazard of the main seismogenic structures recognized in the Central and Southern Apennines region, for which both historical and paleoseismological data are available. This study provides the opportunity of reviewing the problems connected with the estimate of the parameters of a renewal model in case of characteristic earthquakes characterized by return times longer than the time spanned by the available catalogues and the applicability of the concept of characteristic earthquake itself. The results show that the estimated effect of earthquake interaction in this region is small compared with the uncertainties affecting the statistical model used for the basic time-dependent hazard assessment.
    Beschreibung: Published
    Beschreibung: B08313
    Beschreibung: 3.1. Fisica dei terremoti
    Beschreibung: 3.2. Tettonica attiva
    Beschreibung: 4.2. TTC - Scenari e mappe di pericolosità sismica
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Stress interaction, occurrence probability, characteristic earthquakes ; 01. Atmosphere::01.02. Ionosphere::01.02.03. Forecasts ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 32
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    Rupture process of the 2007 Niigata-ken Chuetsu-oki earthquake by non-linear joint inversion of strong motion and GPS data (2008)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: We image the rupture history of the 2007 Niigata-ken Chuestu-oki (Japan) earthquake by a nonlinear joint inversion of strong motion and GPS data, retrieving peak slip velocity, rupture time, rise time and slip direction. The inferred rupture model contains two asperities; a small patch near the nucleation and a larger one located 10÷15 km to the south-west. The maximum slip ranges between 2.0 and 2.5 m and the total seismic moment is 1.6×1019 Nm. The inferred rupture history is characterized by rupture acceleration and directivity effects, which are stable features of the inverted models. These features as well as the source-to-receiver geometry are discussed to interpret the high peak ground motions observed (PGA is 1200 gals) at the Kashiwazaki-Kariwa nuclear power plant (KKNPP), situated on the hanging-wall of the causative fault. Despite the evident source effects, predicted PGV underestimates the observed values at KKNPP by nearly a factor of 10.
    Beschreibung: Published
    Beschreibung: L16306
    Beschreibung: 3.1. Fisica dei terremoti
    Beschreibung: JCR Journal
    Beschreibung: partially_open
    Schlagwort(e): rupture process ; inversion ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 33
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    Sliding episodes during the 2002–2003 Stromboli lava effusion: Insights from seismic, volcanic, and statistical data analysis (2008)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 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.
    Beschreibung: This work was supported financially by Istituto Nazionale di Geofisica e Vulcanologia and Dipartimento per la Protezione Civile, project INGV-DPC V4/02.
    Beschreibung: Published
    Beschreibung: Q04022
    Beschreibung: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): 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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  • 34
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    Strong evidence for non-similar earthquake source scaling in central Italy (2008)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: scaling of seismic sources of the Central Apennines (Italy) is investigated using broadband seismograms from the Colfiorito sequence (4〈=Mw〈=6 ). Our results are not consistent with self-similar scaling, and can be described by the following relationship: M0~fc^-(3_epsilon), where epsilon=1.7+-0.3 . We speculate that dynamic fault lubrication by fluid pressurization may be responsible for such extreme behavior, and use our results for the calibration of a weak-motion-based predictive relationship for the ground motion ( Mw〈=4.1) up to Mw~6 for this region.
    Beschreibung: Published
    Beschreibung: L17303
    Beschreibung: 3.1. Fisica dei terremoti
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Self-similarity ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 35
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    Unmanned aerial vehicle measurements of volcanic carbon dioxide fluxes (2008)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 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.
    Beschreibung: Published
    Beschreibung: L06303
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): 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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  • 36
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    Source process of the September 12, 2007 MW 8.4 Southern Sumatra earthquake from tsunami tide gauge record inversion (2008)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: We infer the slip distribution and average rupture velocity of the magnitude MW 8.4 September 12, 2007, southern Sumatra earthquake from available tide-gauge records of the ensuing tsunami. We select 9 waveforms recorded along the west coast of Sumatra and in the Indian Ocean. Slip distribution and rupture velocity are determined simultaneously by means of a non linear inversion method. We find high slip values (∼10 m) into a patch 100 km long and 50 km large, between 20 and 30 km of depth, about 100 km north-west from the epicenter. We conclude this earthquake did not rupture the whole area of the 1833 event, indicating some slip has still to occurr. Our estimate of rupture velocity is of 2.1±0.4 km/sec. The relatively large depth of the main slip patch is the likely explanation for the low damaging observed tsunami.
    Beschreibung: Published
    Beschreibung: L02310
    Beschreibung: 3.1. Fisica dei terremoti
    Beschreibung: JCR Journal
    Beschreibung: partially_open
    Schlagwort(e): Sumatra ; tsunami ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 37
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    Scanning tomography of SO2 distribution in a volcanic gas plume (2008)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 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.
    Beschreibung: Published
    Beschreibung: L17811
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): 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
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 38
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    Contemporary total dissolved gas pressure and soil temperature anomalies recorded at Stromboli volcano (Italy) (2007)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 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.
    Beschreibung: Published
    Beschreibung: L08301
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): 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
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 39
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    Estimates of slip weakening distance for different dynamic rupture models (2007)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: We model the dynamic propagation of a 2-D in-plane crack obeying to either slip weakening (SW) or rate- and state-dependent friction laws (R&S). We compare the value of slip weakening distance (Dc), adopted or estimated from the traction versus slip curves, with the critical slip distance measured as the slip at the time of peak slip velocity (Dc'). The adopted friction law and the constitutive parameters control the slip acceleration as well as the timing and the amplitude of peak slip velocity. Our simulations with R&S show that the direct effect of friction and the friction behavior at high slip rates affect the timing of peak slip velocity and thus control the ratio Dc' /Dc. The difference observed in this study between the Dc values and the inferred Dc' can range between few percent up to 50%.
    Beschreibung: Published
    Beschreibung: L02611
    Beschreibung: 3.1. Fisica dei terremoti
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Modeling ; Earthquake dynamics and mechanics ; Earthquake parameters ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 40
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    The dependence of traction evolution on the earthquake source time function adopted in kinematic rupture models (2007)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: We compute the temporal evolution of traction by solving the elasto-dynamic equation and by using the slip velocity history as a boundary condition on the fault plane. We use different source time functions to derive a suite of kinematic source models to image the spatial distribution of dynamic and breakdown stress drop, strength excess and critical slip weakening distance (Dc). Our results show that the source time functions, adopted in kinematic source models, affect the inferred dynamic parameters. The critical slip weakening distance, characterizing the constitutive relation, ranges between 30% and 80% of the total slip. The ratio between Dc and total slip depends on the adopted source time functions and, in these applications, is nearly constant over the fault. We propose that source time functions compatible with earthquake dynamics should be used to infer the traction time history.
    Beschreibung: Published
    Beschreibung: L04609
    Beschreibung: 3.1. Fisica dei terremoti
    Beschreibung: JCR Journal
    Beschreibung: partially_open
    Schlagwort(e): Earthquake dynamics and mechanics ; Earthquake parameters ; Theory and modeling ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 41
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    Evidence for departure in self-similarity: a new spectral ratio method using narrowband coda envelopes (2007)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: The use of local and regional S-wave coda is shown to provide stable amplitude ratios that better constrains source differences between event pairs. We first compared amplitude ratio performance between local and near regional S and coda waves in the San Francisco Bay region for moderate-sized events, then applied the coda spectral ratio method to the 1999 Hector Mine mainshock and its larger aftershocks. We find (1) average amplitude ratio standard deviations using coda are ~0.05 to 0.12, roughly a factor of 3 smaller than direct S-waves for 0.2 〈 f 〈 15.0 Hz; (2) coda spectral ratios for the Mw 7.0 Hector Mine earthquake and its aftershocks show a clear departure from self-similarity, consistent with other studies using the same datasets; and (3) event-pairs (Green’s function and target events) can be separated by ~25 km for coda amplitudes without any appreciable degradation, in sharp contrast to direct waves.
    Beschreibung: Published
    Beschreibung: L11303
    Beschreibung: 3.1. Fisica dei terremoti
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): non-self-similarity ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 42
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    Lava flow identification and aging by means of lidar intensity: Mount Etna case (2007)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 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.
    Beschreibung: Published
    Beschreibung: B02201
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: 3.5. Geologia e storia dei sistemi vulcanici
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): lava flows ; mapping ; lidar ; 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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  • 43
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    Real-time measurement of volcanic H2S and SO2 concentrations by UV spectroscopy (2006)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 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.
    Beschreibung: Published
    Beschreibung: 1652
    Beschreibung: partially_open
    Schlagwort(e): 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
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 44
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    Great Sumatra Earthquake Registers on Electrostatic Sensor (2006)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Strong electrical signals that correspond to the Mw = 9.3 earthquake of 26 December 2004, which occurred at 0058:50.7 UTC off the west coast of northern Sumatra, Indonesia, were recorded by an electrostatic sensor (a device that detects short-term variations in Earth’s electrostatic fi eld) at a seismic station in Italy, which had been installed to study the infl uence of local earthquakes on a new landslide monitoring system. Electrical signals arrived at the station practically instantaneously and were detected up to several hours before the onset of the Sumatra earthquake (Figure 1) as well as before local quakes. The corresponding seismic signals (p-waves) arrived 740 seconds after the start of the earthquake. Because the electrical signals travel at the speed of light, electrical monitoring for the global detection of very strong earthquakes could be an important tool in signifi cantly increasing the hazard alert window.
    Beschreibung: Published
    Beschreibung: 445-460
    Beschreibung: open
    Schlagwort(e): Sumatra earthquake ; electrostatic signals ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 45
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    Intercomparison of volcanic gas monitoring methodologies performed on Vulcano Island, Italy (2005)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 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.
    Beschreibung: Published
    Beschreibung: L02610
    Beschreibung: partially_open
    Schlagwort(e): 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
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 46
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    On the slip-weakening behavior of rate- and state-dependent constitutive laws (2005)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: We study the dynamic traction behavior within the cohesive zone during the propagation of earthquake ruptures adopting rate and state dependent constitutive relations. The resulting slip weakening curve displays an equivalent slip weakening distance (D0_eq), which is different from the parameter L controlling the state variable evolution. The adopted constitutive parameters (a, b, L) control the slip weakening behavior and the absorbed fracture energy. The dimension of the nucleation patch scales with L and not with D0_eq. We propose a scaling relation between these two lengthscale parameters which prescribes that D0_eq/L ~ 15.
    Beschreibung: Published
    Beschreibung: 1-4
    Beschreibung: open
    Schlagwort(e): Earthquake dynamics and mechanics ; Earthquake parameters ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 47
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    A PTFE membrane for the in situ extraction of dissolved gases in natural waters: Theory and applications (2005)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 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.
    Beschreibung: - European Social Fund.
    Beschreibung: Published
    Beschreibung: Q09005
    Beschreibung: partially_open
    Schlagwort(e): 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
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 48
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    Accurate measurement of volcanic SO2 flux: Determination of plume transport speed and integrated SO2 concentration with a single device (2005)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 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.
    Beschreibung: Published
    Beschreibung: Q02003
    Beschreibung: partially_open
    Schlagwort(e): 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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  • 49
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    Slow rupture of an aseismic fault in a seismogenic region of Central Italy (2005)
    American Geophysical Union
    Details
    Publikationsdatum: 2012-02-03
    Beschreibung: Slow earthquakes and afterslips prove that the Earth does not have just two response time scales, i.e. that of tectonic loading and that of regular earthquakes. A swarm of slow earthquakes, with time constants of the order of hundreds of seconds, has been detected by a laser interferometer below the Gran Sasso massif (Italy). We analyse and model these observations to identify a very plausible source in a local fault, with no historic seismic behavior. While slow earthquakes occurring in subduction zones, and at the transition between locked and stably sliding segments of the San Andreas fault, are often associated with seismic events, in the case of the Apennines there is no correlation between local seismicity and slow earthquakes. Slow earthquakes, therefore, may also represent a specific failure behavior for a seismically locked fault, adding further complexity to the interpretation of geologic data for seismic hazard estimates.
    Beschreibung: Published
    Beschreibung: 2219
    Beschreibung: open
    Schlagwort(e): Earthquake dynamics and mechanics ; Seismic hazard assessment and prediction ; Seismicity and seismotectonics ; 04. Solid Earth::04.01. Earth Interior::04.01.05. Rheology ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 50
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    Chemical mapping of a fumarolic field: La Fossa Crater, Vulcano Island (Aeolian Islands, Italy) (2005)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 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.
    Beschreibung: Published
    Beschreibung: L13309
    Beschreibung: partially_open
    Schlagwort(e): 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
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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