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  • 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases
  • 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability
  • Wiley-Blackwell  (8)
  • American Association for the Advancement of Science  (2)
  • Blackwell Publishing Ltd  (2)
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  • 1
    Publikationsdatum: 2020-12-15
    Beschreibung: We present a time-independent gridded earthquake rate forecast for the European region including Turkey. The spatial component of our model is based on kernel density estimation techniques, which we applied to both past earthquake locations and fault moment release on mapped crustal faults and subduction zone interfaces with assigned slip rates. Our forecast relies on the assumption that the locations of past seismicity is a good guide to future seismicity, and that future large-magnitude events occur more likely in the vicinity of known faults. We show that the optimal weighted sum of the corresponding two spatial densities depends on the magnitude range considered. The kernel bandwidths and density weighting function are optimized using retrospective likelihood-based forecast experiments. We computed earthquake activity rates (a- and b-value) of the truncated Gutenberg–Richter distribution separately for crustal and subduction seismicity based on a maximum likelihood approach that considers the spatial and temporal completeness history of the catalogue. The final annual rate of our forecast is purely driven by the maximum likelihood fit of activity rates to the catalogue data, whereas its spatial component incorporates contributions from both earthquake and fault moment-rate densities. Our model constitutes one branch of the earthquake source model logic tree of the 2013 European seismic hazard model released by the EU-FP7 project ‘Seismic HAzard haRmonization in Europe’ (SHARE) and contributes to the assessment of epistemic uncertainties in earthquake activity rates. We performed retrospective and pseudo-prospective likelihood consistency tests to underline the reliability of our model and SHARE’s area source model (ASM) using the testing algorithms applied in the collaboratory for the study of earthquake predictability (CSEP). We comparatively tested our model’s forecasting skill against the ASM and find a statistically significant better performance for testing periods of 10–20 yr. The testing results suggest that our model is a viable candidate model to serve for long-term forecasting on timescales of years to decades for the European region.
    Beschreibung: EC-Research FP7-projects, SHARE, under grant agreement No. 226967 and NERA, under grant agreement No. 262330
    Beschreibung: Published
    Beschreibung: 1159-1172
    Beschreibung: 2T. Tettonica attiva
    Beschreibung: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): Probabilistic forecasting ; Statistical seismology ; Europe ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    facet.materialart.
    Unbekannt
    American Association for the Advancement of Science
    Publikationsdatum: 2017-04-04
    Beschreibung: BREVIA
    Beschreibung: Current emission inventories require an additional "unknown" source to balance the global atmospheric budgets of ethane (C2H6). Here, we provide evidence that a substantial part of the missing source can be attributed to natural gas seepage from petroliferous, geothermal, and volcanic areas. Such geologic sources also inject propane (C3H8) into the atmosphere. The analysis of a large data set of methane (CH4), ethane, and propane concentrations in surface gas emissions of 238 sites from different geographic and geologic areas, coupled with published estimates of geomethane emissions, suggests that Earth's degassing accounts for at least 17% and 10% of total ethane and propane emissions, respectively.
    Beschreibung: Published
    Beschreibung: 478
    Beschreibung: 3.8. Geofisica per l'ambiente
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Ethane ; Propane ; Geologic emissions ; Seepage ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    facet.materialart.
    Unbekannt
    American Association for the Advancement of Science
    Publikationsdatum: 2017-04-04
    Beschreibung: Episodes of nonvolcanic tremor and accompanying slow slip recently have been observed in the subduction zones of Japan and Cascadia. In Cascadia, such episodes typically last a few weeks, and differ from “normal” earthquakes in their source location and momentduration scaling. The three most recent episodes in the Puget Sound/Southern Vancouver Island portion of the Cascadia subduction zone have been exceptionally well recorded. In each episode, we see clear pulsing of tremor activity with periods of 12.4 and 24-25 hours, the same as the principal lunar and lunisolar tides. This indicates that the small stresses associated with the solid-earth and ocean tides influence the genesis of tremor much more effectively than they do “normal” earthquakes. Because the lithostatic stresses are 105 times larger than those associated with the tides, we argue that tremor occurs on very weak faults.
    Beschreibung: Published
    Beschreibung: 186 -189
    Beschreibung: 3.1. Fisica dei terremoti
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Nonvolcanic ; tremor ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Publikationsdatum: 2017-04-04
    Beschreibung: The paper describes a case of a natural emission of methane from soil in an urban development area, generating a significant risk for the local population and buildings, due to gas explosiveness and asphyxiation potential. The site is located on the south-western margin of the East-European Platform in eastern Romania, in a hydrocarbon-prone area crossed by the Pericarpathian lineament and regional faults. Molecular composition of gas and stable isotopic analyses of methane (CH4〉90%, δ to the power of 13 C1: -49.4‰, δD1: -173.4‰) indicate a dominant thermogenic origin, with significant amounts of C2-C5 alkanes (~5%), likely migrating through faults from a deep reservoir. Possible candidates are the Saucesti and Secuieni gas fields, located in the same petroleum system. Two surface geochemical surveys, based on closed-chamber flux measurements, were performed to assess the degassing intensity and the extent of the affected area. Methane fluxes from soil reach orders of 10 to the power of 4 mg m to the power of -2 day to the power of -1. Gas seepage mainly occurs in one zone 30 000 m2 wide, and it is likely controlled by channeling along a fault and gas accumulation in permeable sediments and shallow subsoil. The estimated total CH4 emission is about 40 t year to the power of -1 CH4, of which 8–9 t year to the power of -1 are naturally released from soil and 30–35 t year to the power of -1 are emitted from shallow boreholes. These wells have likely channeled the gas accumulated in shallow alluvial sediment but gas flux from soil is still high and mitigation measures are needed to reduce the risk for humans and buildings.
    Beschreibung: Published
    Beschreibung: 311-320
    Beschreibung: 3.8. Geofisica per l'ambiente
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): gas hazard ; methane seepage ; soil degassing ; thermogenic gas ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Publikationsdatum: 2017-04-04
    Beschreibung: The Chimaera gas seep, near Antalya (SW Turkey), has been continuously active for thousands of years and it is known to be the source of the first Olympic fire in the Hellenistic period. New and thorough molecular and isotopic analyses including methane (approximately 87% v/v; δ to the power of 13 C1 from -7.9‰ to -12.3‰; δ to the power of 13 D1 from -119‰ to -124‰), light alkanes (C2 + C3 + C4 + C5 = 0.5%; C6+: 0.07%; δ to the power of 13 C2 from -24.2‰ to -26.5‰; δ to the power of 13 C3 from -25.5‰ to -27‰), hydrogen (7.5–11%), carbon dioxide (0.01–0.07%; δ to the power of 13 CCO2: -15‰), helium (approximately 80 ppmv; R/Ra: 0.41) and nitrogen (2–4.9%; δ to the power of 15 N from -2‰ to -2.8‰) converge to indicate that the seep releases a mixture of organic thermogenic gas, related to mature type III kerogen occurring in Palaeozoic and Mesozoic organic-rich sedimentary rocks, and abiogenic gas produced by low-temperature serpentinization in the Tekirova ophiolitic unit. Methane is not related to mantle or magma degassing. The abiogenic fraction accounts for about half of the total gas released, which is estimated to be well beyond 50 ton year to the power of -1. Ophiolites and limestones are in contact along a tectonic dislocation leading to gas mixing and migration to the Earth’s surface. Chimaera represents the biggest emission of abiogenic methane on land discovered so far. Deep and pressurized gas accumulations are necessary to sustain the Chimaera gas flow for thousands of years and are likely to have been charged by an active inorganic source.
    Beschreibung: Published
    Beschreibung: 263-273
    Beschreibung: 3.8. Geofisica per l'ambiente
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): abiogenic methane ; isotopic composition ; ophiolites ; seep ; serpentinization ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Publikationsdatum: 2017-04-04
    Beschreibung: The 2009 April 6, Mw= 6.3 L’Aquila earthquake occurred within a complex system of NW–SE trending normal faults in the Abruzzi Central Apennines (Italy). We analyse the coseismic deformation as measured by 〉70 global positioning system (GPS) stations, both from continuous and survey-mode networks, providing unprecedented details for a moderate normal faulting earthquake in Italy from GPS measurements. We use rectangular, uniform-slip, dislocations embedded in an elastic, homogeneous and isotropic half-space and a constrained, non-linear optimization algorithm, to solve for the best-fitting rectangular dislocation geometry and coseismic-slip distribution. We use a bootstrap approach to investigate uncertainties in the model parameters and define confidence bounds for all the inverted parameters. The rupture occurred on a N129°E striking and 50° southwestward dipping normal fault, in agreement with geological observations of surface breaks along the Paganica fault. Our distributed slip model exhibits a zone of relatively higher slip (〉60 cm) between ∼1.5 and ∼11 km depth, along a roughly downdip, NW–SE elongated patch, confined within the fault plane inverted assuming uniform-slip. The highest slip, of the order of ∼1 m, occurred on a ∼16 km2 area located at ∼5 km depth, SE of the mainshock epicentre. The analysis of model resolution suggests that slip at depth below ∼5 km can be resolved only at a spatial scale larger than 2 km, so a finer discretization of different asperities within the main patch of coseismic-slip is not allowed by GPS data. We compute the coseismic Coulomb stress changes in the crustal volume affected by the major aftershocks, and compare the results obtained from the uniform-slip and the heterogeneous-slip models. We find that most of the large aftershocks occurred in areas of Coulomb stress increase of 0.2–13 bar and that a deepening of the slip distribution down to a depth greater than 6 km in the SE part of the fault plane, in agreement with the inverted slip model, can explain the deepest, April 7, Mw 5.3 aftershock.
    Beschreibung: Published
    Beschreibung: 473-489
    Beschreibung: 1.9. Rete GPS nazionale
    Beschreibung: 3.2. Tettonica attiva
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Satellite geodesy ; Space geodetic surveys ; Earthquake ground motions ; Earthquake source observations ; Earthquake interaction, forecasting, and prediction ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    facet.materialart.
    Unbekannt
    Wiley-Blackwell
    Publikationsdatum: 2017-04-04
    Beschreibung: We consider a seismicity forecast experiment conducted during the last 4 yr. At the beginning of each year, three models make a 1-yr forecast of the distribution of large earthquakes everywhere on the Earth. The forecasts are generated and the observations are collected in the Collaboratory for the Study of Earthquake Predictability (CSEP). We apply CSEP likelihood measures of consistency and comparison to see how well the forecasts match the observations, and we compare results from some intuitive reference models. These results illustrate some undesirable properties of the consistency tests: the tests can be extremely sensitive to only a few earthquakes, and yet insensitive to seemingly obvious flaws—a na ̈ıve hypothesis that large earthquakes are equally likely everywhere is not always rejected. The results also suggest that one should check the assumptions of the so-called T and W comparison tests, and we illustrate some methods to do so. As an extension of model assessment, we explore strategies to combine forecasts, and we discuss the implications for operational earthquake forecasting. Finally, we make suggestions for the next generation of global seismicity forecast experiments.
    Beschreibung: Published
    Beschreibung: 422-431
    Beschreibung: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): probabilistic forecasting ; statistical seismology ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Publikationsdatum: 2017-04-04
    Beschreibung: Probabilistic tsunami hazard analysis (PTHA) relies on computationally demanding numerical simulations of tsunami generation, propagation, and non-linear inundation on high-resolution topo-bathymetric models. Here we focus on tsunamis generated by co-seismic sea floor dis- placement, that is, on Seismic PTHA (SPTHA). A very large number of tsunami simulations are typically needed to incorporate in SPTHA the full expected variability of seismic sources (the aleatory uncertainty). We propose an approach for reducing their number. To this end, we (i) introduce a simplified event tree to achieve an effective and consistent exploration of the seismic source parameter space; (ii) use the computationally inexpensive linear approximation for tsunami propagation to construct a preliminary SPTHA that calculates the probability of maximum offshore tsunami wave height (H Max) at a given target site; (iii) apply a two-stage filtering procedure to these ‘linear’ SPTHA results, for selecting a reduced set of sources and (iv) calculate ‘non-linear’ probabilistic inundation maps at the target site, using only the selected sources. We find that the selection of the important sources needed for approximating probabilistic inundation maps can be obtained based on the offshore HMax values only. The filtering procedure is semi-automatic and can be easily repeated for any target sites. We describe and test the performances of our approach with a case study in the Mediterranean that considers potential subduction earthquakes on a section of the Hellenic Arc, three target sites on the coast of eastern Sicily and one site on the coast of southern Crete. The comparison between the filtered SPTHA results and those obtained for the full set of sources indicates that our approach allows for a 75–80 per cent reduction of the number of the numerical simulations needed, while preserving the accuracy of probabilistic inundation maps to a reasonable degree.
    Beschreibung: Published
    Beschreibung: 574-588
    Beschreibung: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): Tsunami ; Hazard ; Probabilistic ; Subduction ; Mediterranean ; SPTHA ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Publikationsdatum: 2017-04-04
    Beschreibung: The Solfatara is one of the major volcanoes of the Phlegrean Fields (Campi Flegrei) volcanic complex, and it is located in a densely populated area a few kilometres west of the city of Naples. It is an active resurgent caldera that has been characterized by a rich history of surface–ground deformation and soil diffuse degassing and fumarolic emissions, which are indications of the top of a hydrothermal plume. A seismic survey was completed in May 2009 for the characterization of the main subsurface features of the Solfatara. Using the complete data set, we have carried out surface wave inversion with high spatial resolution. A classical minimization of a least-squares objective function was first computed to retrieve the dispersion curves of the surface waves. Then, the fitting procedure between the data and a three-sedimentlayer forward model was carried out (to a depth of 7 m), using an improved version of the neighbourhood algorithm. The inversion results indicate a NE-SW fault, which is not visible at the surface. This was confirmed by a temperature survey conducted in 2010. A passive seismic experiment localized the ambient noise sources that correlate well with the areas of high CO2 flux and high soil temperatures. Finally, considering that the intrinsic attenuation is proportional to the frequency, a centroid analysis provides an overview of the attenuation of the seismic waves, which is closely linked to the petrophysical properties of the rock. These different approaches that merge complete active and passive seismic data with soil temperature and CO2 flux maps confirm the presence of the hydrothermal system plume. Some properties of the top of the plume are indicated and localized.
    Beschreibung: Published
    Beschreibung: 1725–1733
    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): Inverse theory ; Tomography ; Hydrothermal systems ; Europe ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Publikationsdatum: 2022-06-08
    Beschreibung: Although no deterministic and reliable earthquake precursor is known to date, we are steadily gaining insight into probabilistic forecasting that draws on space–time characteristics of earthquake clustering. Clustering-based models aiming to forecast earthquakes within the next 24 hours are under test in the global project ‘Collaboratory for the Study of Earthquake Predictability’ (CSEP). The 2011 March 11 magnitude 9.0 Tohoku-Oki earthquake in Japan provides a unique opportunity to test the existing 1-day CSEP models against its unprecedentedly active aftershock sequence. The original CSEP experiment performs tests after the catalogue is finalized to avoid bias due to poor data quality. However, this study differs from this tradition and uses the preliminary catalogue revised and updated by the Japan Meteorological Agency (JMA), which is often incomplete but is immediately available. This study is intended as a first step towards operability-oriented earthquake forecasting in Japan. Encouragingly, at least one model passed the test in most combinations of the target day and the testing method, although the models could not take account of the megaquake in advance and the catalogue used for forecast generation was incomplete. However, it can also be seen that all models have only limited forecasting power for the period immediately after the quake. Our conclusion does not change when the preliminary JMAcatalogue is replaced by the finalized one, implying that the models perform stably over the catalogue replacement and are applicable to operational earthquake forecasting. However, we emphasize the need of further research on model improvement to assure the reliability of forecasts for the days immediately after the main quake. Seismicity is expected to remain high in all parts of Japan over the coming years. Our results present a way to answer the urgent need to promote research on time-dependent earthquake predictability to prepare for subsequent large earthquakes in the near future in Japan.
    Beschreibung: Published
    Beschreibung: 653-658
    Beschreibung: 3.1. Fisica dei terremoti
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): Time-series analysis ; Probabilistic forecasting ; Seismicity and tectonics ; Computational seismology ; Statistical seismology ; Asia ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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