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  • Europe  (5)
  • Seismic attenuation  (5)
  • Wiley-Blackwell  (10)
  • American Association of Petroleum Geologists (AAPG)
  • Springer Nature
  • 2020-2022
  • 2010-2014  (10)
  • 1945-1949
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  • 1
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    A smoothed stochastic earthquake rate model considering seismicity and fault moment release for Europe (2014)
    Wiley-Blackwell
    Details
    Publication Date: 2020-12-15
    Description: 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.
    Description: EC-Research FP7-projects, SHARE, under grant agreement No. 226967 and NERA, under grant agreement No. 262330
    Description: Published
    Description: 1159-1172
    Description: 2T. Tettonica attiva
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: restricted
    Keywords: 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)
    Type: article
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  • 2
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    Seismic energy envelopes in volcanic media: in need of boundary conditions (2013)
    Wiley-Blackwell
    Details
    Publication Date: 2020-12-15
    Description: Seismogram envelopes recorded at Campi Flegrei caldera show diffusive characteristics as well as steep amplitude increases in the intermediate and late coda, which can be related to the presence of a non-uniformly scattering medium. In this paper, we first show the results of a simulation with a statistical model considering anisotropic scattering interactions, in order to match coda-envelope duration and shape.We consider as realistic parameters for a volcanic caldera the presence of large square root velocity fluctuations (10 per cent) and two typical correlation lengths for such an heterogeneous crust, a = 0.1 and 1 km. Then, we propose the inclusion of a diffusive boundary condition in the stochastic description of multiple scattering, in order to model intermediate and late coda intensities, and particularly the sharp intensity peaks at some stations in the caldera. Finally, we show that a reliable 2-D synthetic model of the envelopes produced by earthquakes vertically sampling a small region can be obtained including a single drastic change of the scattering properties of the volcano, that is, a caldera rim of radius 3 km, and sections varying between 2 and 3 km. These boundary conditions are diffusive, which signifies that the rim must have more scattering potential than the rest of the medium, with its diffusivity 2–3 orders of magnitude lower than the one of the background medium, so that the secondary sources on its interface(s) could enhance coda intensities. We achieve a good first-order model of high-frequency (18 Hz) envelope broadening adding to the Monte Carlo solution for the incident flux the secondary source effects produced by a closed annular boundary, designed on the caldera rim signature at 1.5 km depth. At lower frequencies (3 Hz) the annular boundary controls the intermediate and late coda envelope behaviour, in a way similar to an extended diffusive source. In our interpretation, the anomalous intensities observed at several stations and predicted by the final Monte Carlo solutions are mainly due to the diffusive transmission reflection from a scattering object of increased scattering power, and are controlled by its varying thickness.
    Description: This work was carried out under the HPC-Europa2 project (project number: 228398) with the support of the European Commission Capacities Area-Research Infrastructures Initiative. We thank the whole staff at EPCC (Edinburgh Parallel Computing Centre) in Edinburgh and particularly Dr. Adam Carter for their help in both developing and parallelizing the code. The challenging comments and suggestions of the editor and two anonymous reviewers helped both in focusing the aim and in overcoming the strong limits of a previous version of the paper.
    Description: Published
    Description: 1102–1119
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: restricted
    Keywords: Numerical solutions; ; Seismic anisotropy; ; Seismic attenuation ; Seismic tomography ; Wave scattering and diffraction ; Calderas ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    Frequency dependent Qα and Qβ in the Umbria-Marche (Italy) region using a quadratic approximation of the coda-normalization method (2013)
    Wiley-Blackwell
    Details
    Publication Date: 2017-04-04
    Description: The coda normalization method is one of the most used methods in the inference of attenuation parameters Qα and Qβ . Since, in this method, the geometrical spreading exponent γ is an unknown model parameter, the most part of studies assumes a fixed γ , generally equal to 1. However γ and Q could be also jointly inferred from the non-linear inversion of codanormalized logarithms of amplitudes, but the trade-off between γ and Q could give rise to unreasonable values of these parameters. To minimize the trade-off between γ and Q, an inversion method based on a parabolic expression of the coda-normalization equation has been developed. The method has been applied to the waveforms recorded during the 1997 Umbria-Marche seismic crisis. The Akaike criterion has been used to compare results of the parabolic model with those of the linear model, corresponding to γ = 1. A small deviation from the spherical geometrical spreading has been inferred, but this is accompanied by a significant variation of Qα and Qβ values. For almost all the considered stations, Qα smaller than Qβ has been inferred, confirming that seismic attenuation, in the Umbria-Marche region, is controlled by crustal pore fluids.
    Description: Published
    Description: 1726-1731
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: restricted
    Keywords: Seismic attenuation ; coda normalization method ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
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    Spatial distribution of intrinsic and scattering seismic attenuation in active volcanic islands – I: model and the case of Tenerife Island (2013)
    Wiley-Blackwell
    Details
    Publication Date: 2017-04-04
    Description: The complex volcanic system of Tenerife Island is known to have a highly heterogeneous character, as recently confirmed by velocity tomography.We present new information derived from intrinsic quality factor inverse maps (Qi −1), scattering quality factor inverse maps (Qs −1) and total quality factor inverse maps (Qt −1) obtained for the same region. The data set used in this work is the result of the analysis of an active seismic experiment carried out, using offshore shots (air guns) recorded at over 85 onshore seismic stations. The estimates of the attenuation parameters are based on the assumption that the seismogram energy envelopes are determined by seismic energy diffusion processes occurring inside the island. Diffusion model parameters, proportional to Qi −1 and to Qs −1, are estimated from the inversion of the energy envelopes for any source–receiver couple. They are then weighted with a new graphical approach based on a Gaussian space probability function, which allowed us to create ‘2-D probabilistic maps’ representing the space distribution of the attenuation parameters. The 2-D images obtained reveal the existence of a zone in the centre of the island characterized by the lowest attenuation effects. This effect is interpreted as highly rigid and cooled rocks. This low-attenuation region is bordered by zones of high attenuation, associated with the recent historical volcanic activity. We calculate the transport mean free path obtaining a value of around 4 km for the frequency range 6–12 Hz. This result is two orders of magnitude smaller than values calculated for the crust of the Earth. An absorption length between 10 and 14 km is associated with the average intrinsic attenuation parameter. These values, while small in the context of tectonic regions, are greater than those obtained in volcanic regions such as Vesuvius or Merapi. Such differences may be explained by the magnitude of the region of study, over three times larger than the aforementioned study areas. This also implies deeper sampling of the crust, which is evidenced by a change in the values of seismic attenuation. One important observation is that scattering attenuation dominates over the intrinsic effects, Qi being at least twice the value of Qs.
    Description: This work has been partially supported by the Spanish project Ephestos, CGL2011-29499-C02-01, by the EU project EC-FP7 MEDiterranean SUpersite Volcanoes (MED-SUV), by the Basque Government researcher training program BFI09.277 and by the Regional project ‘Grupo de Investigaci´on en Geof´ısica y Sismolog´ıa de la Junta de Andaluc´ıa, RNM104’. EdP has been partly supported by DPC-INGV projects UNREST SPEED and V2 (Precursori).
    Description: Published
    Description: 1942-1956
    Description: 3.1. Fisica dei terremoti
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: Seismic attenuation ; ; Seismic tomography; ; Volcano seismology ; Wave propagation. ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
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    High-resolution shallow seismic tomography of a hydrothermal area: application to the Solfatara, Pozzuoli (2012)
    Wiley-Blackwell
    Details
    Publication Date: 2017-04-04
    Description: 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.
    Description: Published
    Description: 1725–1733
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: restricted
    Keywords: 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)
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  • 6
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    Crustal structure and seismotectonics of central Sicily (southern Italy): new constraints from instrumental seismicity (2012)
    Wiley-Blackwell
    Details
    Publication Date: 2024-05-09
    Description: In this paper, we propose a new model of the crustal structure and seismotectonics for central Sicily (southern Italy) through the analysis of the depth distribution and kinematics of the instrumental seismicity, occurring during the period from 1983 to 2010, and its comparison with individual geological structures that may be active in the area. The analysed data set consists of 392 earthquakes with local magnitudes ranging from 1.0 to 4.7. We defined a new, detailed 1-D velocity model to relocate the earthquakes that occurred in central Sicily, and we calculated a Moho depth of 37 km and a mean VP/VS ratio of 1.73. The relocated seismic events are clustered mainly in the area north of Caltanissetta (e.g. Mainland Sicily) and in the northeastern sector (Madonie Mountains) of the study area; only minor and greatly dispersed seismicity is located in the western sector, near Belice, and along the southern coast, between Gela and Sciacca. The relocated hypocentral distribution depicts a bimodal pattern: 50 per cent of the events occur within the upper crust at depths less than ~16 km, 40 per cent of the events occur within the middle and depth crust, at depths between 16 and 32 km, and the remaining 10 per cent occur at subcrustal depths. The energy release pattern shows a similar depth distribution. On the basis of the kinematic analysis of 38 newly computed focal plane solutions, two major geographically distinct seismotectonic domains are distinguished: the Madonie Mountain domain, with prevalent extensional and extensional-oblique kinematics associated with upper crust Late Pliocene–Quaternary faulting, and the Mainland Sicily domain, with prevalent compressional and compressional-oblique kinematics associated with thrust faulting, at mid to deep crust depth, along the north-dipping Sicilian Basal Thrust (SBT). The stress inversion of the Mainland Sicily focal solutions integrated with neighbouring mechanisms available in the literature highlights a regional homogeneous compressional tensor, with a subhorizontal NNW–SSE-striking σ1 axis. In addition, on the basis of geodetic data, the Mainland Sicily domain may be attributed to the SSE-ward thrusting of the Mainland Sicily block along the SBT plane. Seismogenic shearing along the SBT at mid-crustal depths was responsible for the unexpected Belice 1968 earthquake (Mw 6.1), with evident implications in terms of hazard assessment.
    Description: Published
    Description: 1237-2252
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: 3.2. Tettonica attiva
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: 5.2. TTC - Banche dati di sismologia strumentale
    Description: JCR Journal
    Description: restricted
    Keywords: Seismicity and tectonics ; Continental tectonics: compressional ; Dynamics: seismotectonics ; Crustal structure ; Europe ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    High frequency attenuation of shear waves in Southeastern Alps and Northern Dinarides (2011)
    Wiley-Blackwell
    Details
    Publication Date: 2021-06-08
    Description: We investigated the high frequency attenuation of S-waves in Southeastern Alps and Northern External Dinarides using waveforms from 331 earthquakes (3.0〈 Mw〈 6.5). The spectral decay parameter, k, was computed using 1345 three component high quality records, collected by the Italian Strong Motion Network (RAN) and by the Short-Period Seismometric Network of North-Eastern Italy (NEI) in the period 1976-2007. Weak motion data from 11 stations of the NEI network and strong motion data collected by 5 accelerometers of the RAN were analyzed. The k parameter was estimated in the 0-250 Km distance range, in a frequency band extending from the corner frequency of the event up to 25 or 45 Hz, using the amplitude acceleration Fourier spectra of S-waves. The observed record-to-record variability of k was modeled by applying a generalized inversion procedure, using both parametric and non-parametric approaches. Our results evidence that k is independent on earthquake size, while it shows both site and distance dependence. Stations of the NEI network present the same increase of k with epicentral distance, Re, and show values of the zero-distance k parameter, k0(S), between 0.017 and 0.053 s. For the whole region, the k increase with distance can be described through a linear model with slope dk/dRe = (1.4±0.1)x10^(-4) s/Km. Assuming an average S-wave velocity, 〈Vs〉=3.34 Km/s between 5 and 15 Km depth, we estimate an average frequency independent quality factor, 〈Qi〉=2140, for the corresponding crustal layer. The non-parametric approach evidences a weak positive concavity of the curve that describes the k increase with Re at about 90 Km distance. This result can be approximated through a piecewise linear function with slopes of 1.0x10^(-4) s/Km and 1.7x10^(-4) s/Km, in accordance with a three layers model where moving from the intermediate to the bottom layer both 〈Qi〉 and 〈Vs〉 decrease. Two regional dependences were found: data from earthquakes located westward to the NEI network evidence weaker attenuation properties, probably because of S-wave reflections from different part of the Moho discontinuity under the eastern Po Plain, at about 25-30 Km depth, while earthquakes located eastward (in western Slovenia), where the Moho deepens up to 45-50 Km, evidence a higher attenuation. Moreover, the k estimates obtained with data from earthquakes located in the area of the 1998 (Mw=5.7) and 2004 (Mw=5.2) Kobarid events are 0.017 s higher than the values predicted for the whole region, probably because of the high level of fracturing that characterizes fault zones. The comparison between measured and theoretical values of k, computed at a few stations with available S-wave velocity profiles, reveals that the major contribution to the total k0(S) is due to the sedimentary column (from surface to 800 m depth). The hard rock section contribution is limited to 0.005 s, in accordance with a maximum contribution of 0.010 s predicted by the non-parametric inversion.
    Description: Published
    Description: 1393-1416
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: open
    Keywords: Earthquake source observations ; Body waves ; Seismic attenuation ; Site effects ; Wave propagation ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
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    A continuous palaeosecular variation record of the last four millennia from the Augusta Bay (Sicily, Italy) (2011)
    Wiley-Blackwell
    Details
    Publication Date: 2021-06-07
    Description: We present a high-resolution palaeomagnetic and rock magnetic study of two cores, MS06 and MS06-SW (6.7 and 1.1 m long, respectively), collected at 72 m below sea level in the Augusta Bay shelf (Eastern Sicily, Ionian Sea, Italy) about 2.3 kmfrom the coastline. Geophysical surveying carried out in the sampling area highlighted the presence of a homogeneous sedimentary sequence that most likely was deposited after the Last Glacial Maximum and was not affected by anthropogenic disturbances. The two cores penetrated a monotonous mud sedimentary sequence, interrupted at ∼3 m depth by a 3–4-cm-thick volcanic sandy layer that is correlated with the tephra fallout deposit produced by the 122 BC plinian eruption of Mt Etna. This tephra, along with radiocarbon dating of nine marine shells and with radioactive tracers for the uppermost 0.3 m (210Pb and 137Cs), provide the chronological constraints for the stratigraphic sequence that resulted younger than 4500 yr BP. Palaeomagnetic and rock magnetic data show that the sample sequence is magnetically homogeneous. A single peak of high magnetic mineral concentration is present and corresponds to the volcanic sandy layer. Palaeomagnetic data allowed the identification of a well-defined characteristic remanent magnetization that provides a high-resolution record of palaeosecular variation (PSV) at the sampling site. The reconstructed PSV curve is in good agreement with the available regional reference PSV curves and with the prediction from recent PSV modelling for Europe. The palaeomagnetic data obtained in this study on the one hand support and refine the age model for the cores, derived from other independent constraints, and on the other hand provide an original high-resolution PSV curve that can serve as a reference for the central Mediterranean over the last 4 ka.
    Description: Published
    Description: 191 - 202
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Palaeointensity ; Palaeomagnetic secular variation ; Marine magnetics and palaeomagnetics ; Europe ; 04. Solid Earth::04.05. Geomagnetism::04.05.02. Geomagnetic field variations and reversals ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    A continuous palaeosecular variation record of the last four millennia from the Augusta Bay (Sicily, Italy) (2010)
    Wiley-Blackwell
    Details
    Publication Date: 2017-04-04
    Description: We present a high-resolution palaeomagnetic and rock magnetic study of two cores, MS06 and MS06-SW (6.7 and 1.1 m long, respectively), collected at 72 m below sea level in the Augusta Bay shelf (Eastern Sicily, Ionian Sea, Italy) about 2.3 kmfrom the coastline. Geophysical surveying carried out in the sampling area highlighted the presence of a homogeneous sedimentary sequence that most likely was deposited after the Last Glacial Maximum and was not affected by anthropogenic disturbances. The two cores penetrated a monotonous mud sedimentary sequence, interrupted at ∼3 m depth by a 3–4-cm-thick volcanic sandy layer that is correlated with the tephra fallout deposit produced by the 122 BC plinian eruption of Mt Etna. This tephra, along with radiocarbon dating of nine marine shells and with radioactive tracers for the uppermost 0.3 m (210Pb and 137Cs), provide the chronological constraints for the stratigraphic sequence that resulted younger than 4500 yr BP. Palaeomagnetic and rock magnetic data show that the sample sequence is magnetically homogeneous. A single peak of high magnetic mineral concentration is present and corresponds to the volcanic sandy layer. Palaeomagnetic data allowed the identification of a well-defined characteristic remanent magnetization that provides a high-resolution record of palaeosecular variation (PSV) at the sampling site. The reconstructed PSV curve is in good agreement with the available regional reference PSV curves and with the prediction from recent PSV modelling for Europe. The palaeomagnetic data obtained in this study on the one hand support and refine the age model for the cores, derived from other independent constraints, and on the other hand provide an original high-resolution PSV curve that can serve as a reference for the central Mediterranean over the last 4 ka.
    Description: In press
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Palaeomagnetic secular variation ; Palaeointensity ; Marine magnetics and palaeomagnetics ; Europe ; 04. Solid Earth::04.05. Geomagnetism::04.05.02. Geomagnetic field variations and reversals ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
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  • 10
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    Crustal heterogeneity highlighted by spatial b-value map in theWellington region of New Zealand (2010)
    Wiley-Blackwell
    Details
    Publication Date: 2017-04-04
    Description: We map the b-value in the subduction zone of theWellington region, NewZealand, using a high quality earthquake catalogue relocated with a 3-D seismic velocity model, consisting of 50 314 events that occurred between 1990 and 2005. In order to investigate heterogeneity in the crust of the overlying plate and in the upper plane of the Wadati–Benioff Zone (WBZ), we analyse a series of cross-sections perpendicular to the strike of the subduction zone. We calculate the b-values selecting events with magnitude of completeness ≥2.4 and depth ≤65 km and projecting the seismicity within 20 km on each side of the cross-sectional planes. We observe areas of high b-value (∼1.7) near the plate interface and regions of low b-value anomalies are detected both in the WBZ in the northwest region below 40 km depth and in the overlying plate in the northern South Island at 10 km depth. The anomalies are statistically significant based on Utsu’s p-test and the bootstrap method and are not data processing method or parameter dependent. We compare the b-value distribution with previously determined 3-D distributions of Vp, Vp/Vs andQp from seismic tomography. This comparison suggests that material inhomogeneity, caused by fluid filled cracks resulting from dehydration of the subducted slab and subducted sediments, is the predominant cause of b-value variation in the shallow part of this subduction zone. Our observations are consistent with a previously proposed conceptual model that fluid distribution in the shallow part of this subduction zone is controlled by the permeability of geological terranes in the overlying plate.
    Description: Published
    Description: 451-460
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: Seismic attenuation ; Seismic tomography ; Statistical seismology ; Subduction zone processes ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
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