The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Mitsuhiro Matsuura - One of the best experts on this subject based on the ideXlab platform.
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interplate seismogenic zones along the kuril japan trench inferred from gps Data Inversion
Nature Geoscience, 2009Co-Authors: Chihiro Hashimoto, Akemi Noda, Takeshi Sagiya, Mitsuhiro MatsuuraAbstract:Stress accumulation between earthquakes results from slip that is insufficient to fully accommodate plate movement. An inverse analysis of GPS Data from the Kuril–Japan trench reveals a trench-parallel belt of stress accumulation with six peaks in the depth range of 10–40 km, suggesting potential source regions for future earthquakes. In the subduction zones around Japan, where four plates interact with one another, large earthquakes have occurred repeatedly1. These interplate earthquakes are part of the process of tectonic stress accumulation and release that is driven by relative plate motion2,3,4. Stress accumulation between earthquakes results from slip deficit (slip that is insufficient to fully accommodate plate movement). For the prediction of large earthquakes, it is therefore important to monitor the distribution of slip deficit on plate interfaces. Here we apply an Inversion method based on Bayesian modelling (using direct and indirect prior information on the magnitude and distribution of fault slip5) to horizontal and vertical velocities from global positioning system Data. For the seismically calm period between 1996 and 2000, we obtain a precise distribution of slip-deficit rates on the interface between the North American and Pacific plates around Japan, which reveals a trench-parallel belt of slip deficit with six peaks in the depth range of 10–40 km. These peaks agree with the source regions of past large interplate earthquakes along the Kuril–Japan trench. We conclude that the slip-deficit zones identified with our method are potential source regions of large earthquakes.
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cmt Data Inversion using a bayesian information criterion to estimate seismogenic stress fields
Geophysical Journal International, 2008Co-Authors: Toshiko Terakawa, Mitsuhiro MatsuuraAbstract:SUMMARY We developed an Inversion method to estimate the stress fields related to earthquake generation (seismogenic stress fields) from the centroid moment tensors (CMT) of seismic events by using Akaike’s Bayesian information criterion (ABIC). On the idea that the occurrence of an earthquake releases some part of the seismogenic stress field around its hypocentre, we define the CMT of a seismic event by a weighted volume integral of the true but unknown seismogenic stress field. Representing each component of the seismogenic stress field by the superposition of a finite number of 3-D basis functions (tri-cubic B-splines), we obtain a set of linear observation equations to be solved for the expansion coefficients (model parameters). We introduce prior constraint on the roughness of the seismogenic stress field and combine it with observed Data to construct a Bayesian model with hierarchic, highly flexible structure controlled by hyper-parameters. The optimum values of the hyper-parameters are objectively determined form observed Data by using ABIC. Given the optimum values of the hyper-parameters, we can obtain the best estimates of model parameters by using a maximum likelihood algorithm. We tested the validity of the Inversion method through numerical experiments on two synthetic CMT Data sets, assuming the distribution of fault orientations to be aligned with the maximum shear stress plane in one case and to be random in the other case. Then we applied the Inversion method to actual CMT Data in northeast Japan, and obtained the pattern of the seismogenic stress field consistent with geophysical and geological observations.
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geodetic Data Inversion based on bayesian formulation with direct and indirect prior information
Geophysical Journal International, 2007Co-Authors: Mitsuhiro Matsuura, Akemi Noda, Yukitoshi FukahataAbstract:SUMMARY Mechanical interaction between adjacent plates, which causes crustal deformation in plate boundary zones, is rationally represented by tangential displacement discontinuity (fault slip) at plate interfaces. Given fault slip distribution, we can compute surface displacements on the basis of elastic dislocation theory. Thus we can determine the functional form of a stochastic model to extract information about unknown fault slip distribution from observed surface displacement Data. In addition to observed Data we usually have prior information. For example, plate tectonics postulates that primary fault slip is parallel to relative plate motion. This is direct prior information that bounds the values of model parameters within certain ranges. From physical consideration we may impose prior constraint on the roughness of fault slip distribution. This is indirect prior information that regulates the structure of stochastic models. By combining the direct and indirect prior information with observed Data in a proper way we constructed a Bayesian model for geodetic Data Inversion, which has a hierarchic flexible structure controlled by hyper-parameters. The optimum values of hyper-parameters are objectively determined from observed Data by using Akaike's Bayesian Information Criterion (ABIC). The Inversion formula derived from the Bayesian model unifies the Jackson–Matsu'ura formula with direct prior information and the Yabuki–Matsu'ura formula with indirect prior information in a rational way. We demonstrated the effectiveness of the unified Inversion formula through the analysis of the surface displacement Data associated with the 1923 Kanto earthquake. In the analysis with direct and indirect prior information we obtained the bimodal distribution of fault slip almost parallel to plate convergence on the North American–Philippine Sea Plate interface. If we ignore the direct prior information in the analysis, additional significant distribution of fault slip perpendicular to plate convergence appears to the east, which is incomprehensible from plate tectonics.
Toshiko Terakawa - One of the best experts on this subject based on the ideXlab platform.
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Stress Data Inversion to estimate collision rate distribution and its application to the Izu Peninsula, Japan
Tectonophysics, 2018Co-Authors: Chihiro Hashimoto, Toshiko TerakawaAbstract:Abstract In convergent plate boundary zones, convergent motion between adjacent plates is accommodated by fault slip along the plate interface (subduction) combined with the compressional deformation of the plates (collision). The collision rate is defined as the ratio of the long-term increase rate of the irrecoverable slip deficit at the plate interface to the full plate convergence rate in order to quantitatively represent this mechanical aspect. The distribution of the collision rate on the plate interface is a major active source that generates a tectonic stress field in the plate interior. We developed a new Inversion method based on these concepts to estimate the collision rate distribution from the patterns of the intraplate tectonic stress fields. In the Inversion, the analytically obtained tectonic stress Data were used and a Bayesian approach was considered. The application of the Inversion method to the Izu collision zone in central Japan revealed that a broad belt of high collision rates surrounded the base of the Izu Peninsula. The collision belt was divided into three parts: (1) a central strong collision zone spreading landwards at the base of the Izu Peninsula, where the value of the collision rate becomes a maximum, (2) an eastern moderate collision zone widely covering the Philippine Sea-North American plate boundary along the Sagami trough, and (3) a western moderate collision zone concentrated in a shallower part of the Philippine Sea-Eurasian plate boundary along the Suruga trough. The central collision zone coincided with the colliding front of the Izu-Ogasawara (Bonin) island arc, which indicated that the estimated collision rate distribution described the actual arc collision process. The eastern and western collision zones might imply a higher absolute strength of their corresponding large interplate seismogenic zones.
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cmt Data Inversion using a bayesian information criterion to estimate seismogenic stress fields
Geophysical Journal International, 2008Co-Authors: Toshiko Terakawa, Mitsuhiro MatsuuraAbstract:SUMMARY We developed an Inversion method to estimate the stress fields related to earthquake generation (seismogenic stress fields) from the centroid moment tensors (CMT) of seismic events by using Akaike’s Bayesian information criterion (ABIC). On the idea that the occurrence of an earthquake releases some part of the seismogenic stress field around its hypocentre, we define the CMT of a seismic event by a weighted volume integral of the true but unknown seismogenic stress field. Representing each component of the seismogenic stress field by the superposition of a finite number of 3-D basis functions (tri-cubic B-splines), we obtain a set of linear observation equations to be solved for the expansion coefficients (model parameters). We introduce prior constraint on the roughness of the seismogenic stress field and combine it with observed Data to construct a Bayesian model with hierarchic, highly flexible structure controlled by hyper-parameters. The optimum values of the hyper-parameters are objectively determined form observed Data by using ABIC. Given the optimum values of the hyper-parameters, we can obtain the best estimates of model parameters by using a maximum likelihood algorithm. We tested the validity of the Inversion method through numerical experiments on two synthetic CMT Data sets, assuming the distribution of fault orientations to be aligned with the maximum shear stress plane in one case and to be random in the other case. Then we applied the Inversion method to actual CMT Data in northeast Japan, and obtained the pattern of the seismogenic stress field consistent with geophysical and geological observations.
Chihiro Hashimoto - One of the best experts on this subject based on the ideXlab platform.
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Stress Data Inversion to estimate collision rate distribution and its application to the Izu Peninsula, Japan
Tectonophysics, 2018Co-Authors: Chihiro Hashimoto, Toshiko TerakawaAbstract:Abstract In convergent plate boundary zones, convergent motion between adjacent plates is accommodated by fault slip along the plate interface (subduction) combined with the compressional deformation of the plates (collision). The collision rate is defined as the ratio of the long-term increase rate of the irrecoverable slip deficit at the plate interface to the full plate convergence rate in order to quantitatively represent this mechanical aspect. The distribution of the collision rate on the plate interface is a major active source that generates a tectonic stress field in the plate interior. We developed a new Inversion method based on these concepts to estimate the collision rate distribution from the patterns of the intraplate tectonic stress fields. In the Inversion, the analytically obtained tectonic stress Data were used and a Bayesian approach was considered. The application of the Inversion method to the Izu collision zone in central Japan revealed that a broad belt of high collision rates surrounded the base of the Izu Peninsula. The collision belt was divided into three parts: (1) a central strong collision zone spreading landwards at the base of the Izu Peninsula, where the value of the collision rate becomes a maximum, (2) an eastern moderate collision zone widely covering the Philippine Sea-North American plate boundary along the Sagami trough, and (3) a western moderate collision zone concentrated in a shallower part of the Philippine Sea-Eurasian plate boundary along the Suruga trough. The central collision zone coincided with the colliding front of the Izu-Ogasawara (Bonin) island arc, which indicated that the estimated collision rate distribution described the actual arc collision process. The eastern and western collision zones might imply a higher absolute strength of their corresponding large interplate seismogenic zones.
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interplate seismogenic zones along the kuril japan trench inferred from gps Data Inversion
Nature Geoscience, 2009Co-Authors: Chihiro Hashimoto, Akemi Noda, Takeshi Sagiya, Mitsuhiro MatsuuraAbstract:Stress accumulation between earthquakes results from slip that is insufficient to fully accommodate plate movement. An inverse analysis of GPS Data from the Kuril–Japan trench reveals a trench-parallel belt of stress accumulation with six peaks in the depth range of 10–40 km, suggesting potential source regions for future earthquakes. In the subduction zones around Japan, where four plates interact with one another, large earthquakes have occurred repeatedly1. These interplate earthquakes are part of the process of tectonic stress accumulation and release that is driven by relative plate motion2,3,4. Stress accumulation between earthquakes results from slip deficit (slip that is insufficient to fully accommodate plate movement). For the prediction of large earthquakes, it is therefore important to monitor the distribution of slip deficit on plate interfaces. Here we apply an Inversion method based on Bayesian modelling (using direct and indirect prior information on the magnitude and distribution of fault slip5) to horizontal and vertical velocities from global positioning system Data. For the seismically calm period between 1996 and 2000, we obtain a precise distribution of slip-deficit rates on the interface between the North American and Pacific plates around Japan, which reveals a trench-parallel belt of slip deficit with six peaks in the depth range of 10–40 km. These peaks agree with the source regions of past large interplate earthquakes along the Kuril–Japan trench. We conclude that the slip-deficit zones identified with our method are potential source regions of large earthquakes.
Marc Descloitres - One of the best experts on this subject based on the ideXlab platform.
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joint electrical and time domain electromagnetism tdem Data Inversion applied to the super sauze earthflow france
Surveys in Geophysics, 2000Co-Authors: Myriam Schmutz, Yves Albouy, Roger Guerin, O Maquaire, Jacques Vassal, J J Schott, Marc DescloitresAbstract:In order to evaluate the risk of an earthflow to evolve abruptly into torrential surge, knowledge of its internal structure is necessary. This study deals with the internal structure of the Super Sauze earthflow developed in black marls in the southern French Alps. Difficulties in this study area are a rough topography, surface heterogeneities and a large thickness variability of the earthflow mass. These conditions hamper the application of geotechnical methods as a preferred investigation mean. Moreover, they pose problems to geophysical investigations and their interpretation.
Yukitoshi Fukahata - One of the best experts on this subject based on the ideXlab platform.
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A non-linear geodetic Data Inversion using ABIC for slip distribution on a fault with an unknown dip angle
Geophysical Journal International, 2008Co-Authors: Yukitoshi Fukahata, Tim J. WrightAbstract:SUMMARY We have developed a method of geodetic Data Inversion for slip distribution on a fault with an unknown dip angle. A common strategy for obtaining slip distribution in previous studies is to first determine the fault geometry by minimizing the square misfit under the assumption of a uniform slip on a rectangular fault, and then apply the usual linear Inversion technique to estimate a slip distribution on the determined fault. It is not guaranteed, however, that the fault determined under the assumption of a uniform slip gives the best fault geometry for a spatially variable slip distribution. The inverse problem is non-linear for cases with unknown fault geometries, but the non-linearity of the problems is actually weak, when we can assume the fault surface to be a flat plane. In particular, when a clear trace of coseismic faults is observed on the Earth’s surface, only the dip angle is an unknown parameter to determine the fault geometry. Then, we regarded the dip angle as an hyperparameter that prescribed the structure of parametric models, and obtained the best estimate of the dip angle using Akaike’s Bayesian Information Criterion (ABIC). With the best estimate of the dip angle, we can obtain the slip distribution on the fault based on the maximum-likelihood principle. We applied the method to the InSAR Data of the 1995 Dinar, Turkey earthquake and obtained a much lower dip angle than the previous analyses.
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geodetic Data Inversion based on bayesian formulation with direct and indirect prior information
Geophysical Journal International, 2007Co-Authors: Mitsuhiro Matsuura, Akemi Noda, Yukitoshi FukahataAbstract:SUMMARY Mechanical interaction between adjacent plates, which causes crustal deformation in plate boundary zones, is rationally represented by tangential displacement discontinuity (fault slip) at plate interfaces. Given fault slip distribution, we can compute surface displacements on the basis of elastic dislocation theory. Thus we can determine the functional form of a stochastic model to extract information about unknown fault slip distribution from observed surface displacement Data. In addition to observed Data we usually have prior information. For example, plate tectonics postulates that primary fault slip is parallel to relative plate motion. This is direct prior information that bounds the values of model parameters within certain ranges. From physical consideration we may impose prior constraint on the roughness of fault slip distribution. This is indirect prior information that regulates the structure of stochastic models. By combining the direct and indirect prior information with observed Data in a proper way we constructed a Bayesian model for geodetic Data Inversion, which has a hierarchic flexible structure controlled by hyper-parameters. The optimum values of hyper-parameters are objectively determined from observed Data by using Akaike's Bayesian Information Criterion (ABIC). The Inversion formula derived from the Bayesian model unifies the Jackson–Matsu'ura formula with direct prior information and the Yabuki–Matsu'ura formula with indirect prior information in a rational way. We demonstrated the effectiveness of the unified Inversion formula through the analysis of the surface displacement Data associated with the 1923 Kanto earthquake. In the analysis with direct and indirect prior information we obtained the bimodal distribution of fault slip almost parallel to plate convergence on the North American–Philippine Sea Plate interface. If we ignore the direct prior information in the analysis, additional significant distribution of fault slip perpendicular to plate convergence appears to the east, which is incomprehensible from plate tectonics.
