The Experts below are selected from a list of 43152 Experts worldwide ranked by ideXlab platform
Simon M Peacock - One of the best experts on this subject based on the ideXlab platform.
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Subduction factory 1. Theoretical mineralogy, densities, Seismic Wave speeds, and H 2 O contents
Journal of Geophysical Research: Solid Earth, 2003Co-Authors: Bradley R. Hacker, Geoffrey A. Abers, Simon M PeacockAbstract:[1] We present a new compilation of physical properties of minerals relevant to subduction zones and new phase diagrams for mid-ocean ridge basalt, lherzolite, depleted lherzolite, harzburgite, and serpentinite. We use these data to calculate H2O content, density and Seismic Wave speeds of subduction zone rocks. These calculations provide a new basis for evaluating the subduction factory, including (1) the presence of hydrous phases and the distribution of H2O within a subduction zone; (2) the densification of the subducting slab and resultant effects on measured gravity and slab shape; and (3) the variations in Seismic Wave speeds resulting from thermal and metamorphic processes at depth. In considering specific examples, we find that for ocean basins worldwide the lower oceanic crust is partially hydrated (< 1.3 wt % H2O), and the uppermost mantle ranges from unhydrated to &SIM;20% serpentinized (&SIM;2.4 wt % H2O). Anhydrous eclogite cannot be distinguished from harzburgite on the basis of Wave speeds, but its &SIM;6% greater density may render it detectable through gravity measurements. Subducted hydrous crust in cold slabs can persist to several gigapascals at Seismic velocities that are several percent slower than the surrounding mantle. Seismic velocities and V-P/V-S ratios indicate that mantle wedges locally reach 60-80% hydration.
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subduction factory 1 theoretical mineralogy densities Seismic Wave speeds and h2o contents
Journal of Geophysical Research, 2003Co-Authors: Bradley R. Hacker, Geoffrey A. Abers, Simon M PeacockAbstract:[1] We present a new compilation of physical properties of minerals relevant to subduction zones and new phase diagrams for mid-ocean ridge basalt, lherzolite, depleted lherzolite, harzburgite, and serpentinite. We use these data to calculate H2O content, density and Seismic Wave speeds of subduction zone rocks. These calculations provide a new basis for evaluating the subduction factory, including (1) the presence of hydrous phases and the distribution of H2O within a subduction zone; (2) the densification of the subducting slab and resultant effects on measured gravity and slab shape; and (3) the variations in Seismic Wave speeds resulting from thermal and metamorphic processes at depth. In considering specific examples, we find that for ocean basins worldwide the lower oceanic crust is partially hydrated (<1.3 wt % H2O), and the uppermost mantle ranges from unhydrated to � 20% serpentinized (� 2.4 wt % H2O). Anhydrous eclogite cannot be distinguished from harzburgite on the basis of Wave speeds, but its � 6% greater density may render it detectable through gravity measurements. Subducted hydrous crust in cold slabs can persist to several gigapascals at Seismic velocities that are several percent slower than the surrounding mantle. Seismic velocities and VP/VS ratios indicate that mantle wedges locally reach 60–80% hydration. INDEX TERMS: 3040 Marine Geology and Geophysics: Plate tectonics (8150, 8155, 8157, 8158); 3660 Mineralogy and Petrology: Metamorphic petrology; 3919 Mineral Physics: Equations of state; 5199 Physical Properties of Rocks: General or miscellaneous; 8123 Tectonophysics: Dynamics, seismotectonics; KEYWORDS: subduction, Seismic velocities, mineral physics, H2O
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subduction factory 1 theoretical mineralogy densities Seismic Wave speeds and h 2 o contents
Journal of Geophysical Research, 2003Co-Authors: Bradley R. Hacker, Geoffrey A. Abers, Simon M PeacockAbstract:[1] We present a new compilation of physical properties of minerals relevant to subduction zones and new phase diagrams for mid-ocean ridge basalt, lherzolite, depleted lherzolite, harzburgite, and serpentinite. We use these data to calculate H2O content, density and Seismic Wave speeds of subduction zone rocks. These calculations provide a new basis for evaluating the subduction factory, including (1) the presence of hydrous phases and the distribution of H2O within a subduction zone; (2) the densification of the subducting slab and resultant effects on measured gravity and slab shape; and (3) the variations in Seismic Wave speeds resulting from thermal and metamorphic processes at depth. In considering specific examples, we find that for ocean basins worldwide the lower oceanic crust is partially hydrated (<1.3 wt % H2O), and the uppermost mantle ranges from unhydrated to � 20% serpentinized (� 2.4 wt % H2O). Anhydrous eclogite cannot be distinguished from harzburgite on the basis of Wave speeds, but its � 6% greater density may render it detectable through gravity measurements. Subducted hydrous crust in cold slabs can persist to several gigapascals at Seismic velocities that are several percent slower than the surrounding mantle. Seismic velocities and VP/VS ratios indicate that mantle wedges locally reach 60–80% hydration. INDEX TERMS: 3040 Marine Geology and Geophysics: Plate tectonics (8150, 8155, 8157, 8158); 3660 Mineralogy and Petrology: Metamorphic petrology; 3919 Mineral Physics: Equations of state; 5199 Physical Properties of Rocks: General or miscellaneous; 8123 Tectonophysics: Dynamics, seismotectonics; KEYWORDS: subduction, Seismic velocities, mineral physics, H2O
Bradley R. Hacker - One of the best experts on this subject based on the ideXlab platform.
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Subduction factory 1. Theoretical mineralogy, densities, Seismic Wave speeds, and H 2 O contents
Journal of Geophysical Research: Solid Earth, 2003Co-Authors: Bradley R. Hacker, Geoffrey A. Abers, Simon M PeacockAbstract:[1] We present a new compilation of physical properties of minerals relevant to subduction zones and new phase diagrams for mid-ocean ridge basalt, lherzolite, depleted lherzolite, harzburgite, and serpentinite. We use these data to calculate H2O content, density and Seismic Wave speeds of subduction zone rocks. These calculations provide a new basis for evaluating the subduction factory, including (1) the presence of hydrous phases and the distribution of H2O within a subduction zone; (2) the densification of the subducting slab and resultant effects on measured gravity and slab shape; and (3) the variations in Seismic Wave speeds resulting from thermal and metamorphic processes at depth. In considering specific examples, we find that for ocean basins worldwide the lower oceanic crust is partially hydrated (< 1.3 wt % H2O), and the uppermost mantle ranges from unhydrated to &SIM;20% serpentinized (&SIM;2.4 wt % H2O). Anhydrous eclogite cannot be distinguished from harzburgite on the basis of Wave speeds, but its &SIM;6% greater density may render it detectable through gravity measurements. Subducted hydrous crust in cold slabs can persist to several gigapascals at Seismic velocities that are several percent slower than the surrounding mantle. Seismic velocities and V-P/V-S ratios indicate that mantle wedges locally reach 60-80% hydration.
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subduction factory 1 theoretical mineralogy densities Seismic Wave speeds and h2o contents
Journal of Geophysical Research, 2003Co-Authors: Bradley R. Hacker, Geoffrey A. Abers, Simon M PeacockAbstract:[1] We present a new compilation of physical properties of minerals relevant to subduction zones and new phase diagrams for mid-ocean ridge basalt, lherzolite, depleted lherzolite, harzburgite, and serpentinite. We use these data to calculate H2O content, density and Seismic Wave speeds of subduction zone rocks. These calculations provide a new basis for evaluating the subduction factory, including (1) the presence of hydrous phases and the distribution of H2O within a subduction zone; (2) the densification of the subducting slab and resultant effects on measured gravity and slab shape; and (3) the variations in Seismic Wave speeds resulting from thermal and metamorphic processes at depth. In considering specific examples, we find that for ocean basins worldwide the lower oceanic crust is partially hydrated (<1.3 wt % H2O), and the uppermost mantle ranges from unhydrated to � 20% serpentinized (� 2.4 wt % H2O). Anhydrous eclogite cannot be distinguished from harzburgite on the basis of Wave speeds, but its � 6% greater density may render it detectable through gravity measurements. Subducted hydrous crust in cold slabs can persist to several gigapascals at Seismic velocities that are several percent slower than the surrounding mantle. Seismic velocities and VP/VS ratios indicate that mantle wedges locally reach 60–80% hydration. INDEX TERMS: 3040 Marine Geology and Geophysics: Plate tectonics (8150, 8155, 8157, 8158); 3660 Mineralogy and Petrology: Metamorphic petrology; 3919 Mineral Physics: Equations of state; 5199 Physical Properties of Rocks: General or miscellaneous; 8123 Tectonophysics: Dynamics, seismotectonics; KEYWORDS: subduction, Seismic velocities, mineral physics, H2O
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subduction factory 1 theoretical mineralogy densities Seismic Wave speeds and h 2 o contents
Journal of Geophysical Research, 2003Co-Authors: Bradley R. Hacker, Geoffrey A. Abers, Simon M PeacockAbstract:[1] We present a new compilation of physical properties of minerals relevant to subduction zones and new phase diagrams for mid-ocean ridge basalt, lherzolite, depleted lherzolite, harzburgite, and serpentinite. We use these data to calculate H2O content, density and Seismic Wave speeds of subduction zone rocks. These calculations provide a new basis for evaluating the subduction factory, including (1) the presence of hydrous phases and the distribution of H2O within a subduction zone; (2) the densification of the subducting slab and resultant effects on measured gravity and slab shape; and (3) the variations in Seismic Wave speeds resulting from thermal and metamorphic processes at depth. In considering specific examples, we find that for ocean basins worldwide the lower oceanic crust is partially hydrated (<1.3 wt % H2O), and the uppermost mantle ranges from unhydrated to � 20% serpentinized (� 2.4 wt % H2O). Anhydrous eclogite cannot be distinguished from harzburgite on the basis of Wave speeds, but its � 6% greater density may render it detectable through gravity measurements. Subducted hydrous crust in cold slabs can persist to several gigapascals at Seismic velocities that are several percent slower than the surrounding mantle. Seismic velocities and VP/VS ratios indicate that mantle wedges locally reach 60–80% hydration. INDEX TERMS: 3040 Marine Geology and Geophysics: Plate tectonics (8150, 8155, 8157, 8158); 3660 Mineralogy and Petrology: Metamorphic petrology; 3919 Mineral Physics: Equations of state; 5199 Physical Properties of Rocks: General or miscellaneous; 8123 Tectonophysics: Dynamics, seismotectonics; KEYWORDS: subduction, Seismic velocities, mineral physics, H2O
Jeroen Tromp - One of the best experts on this subject based on the ideXlab platform.
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Modeling of global Seismic Wave propagation on the Earth Simulator
2020Co-Authors: Seiji Tsuboi, Dimitri Komatitsch, Chen Ji, Jeroen TrompAbstract:We use the Earth Simulator to model Seismic Wave propagation resulting from large earthquakes on a global scale. Simulations are conducted based upon the spectral-element method, a high-degree finite- element technique. We include the full complexity of the Earth, i.e., a three-dimensional Seismic Wave veloci- ty and density structure, a 3-D crustal model, the elliptical figure of the Earth as well as topography and bathymetry. We use 507 nodes of the Earth Simulator (4056 processors) and model the three dimensional Earth with 13.7 billion grid points. A total of 7 terabytes of memory is needed. We have reached a vectoriza- tion ratio of 99.3%, and attained a total performance of 10 teraflops (32% of the peak performance). The very high resolution of the mesh allows us to calculate theoretical Seismic Waves for realistic fully three-dimen- sional Earth model, which are accurate at periods of 3.5 seconds and longer. We have modeled Seismic Waves generated by recent large earthquakes and show the importance of including three-dimensional structure in the Seismic Wave simulation. These theoretical seismograms calculated for fully three-dimensional Earth models should improve our understanding of earthquake source mechanisms and the Earth dynamics.
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numerical modeling of Seismic Wave propagation gridded two way Wave equation methods
GSW Books, 2012Co-Authors: Johan O A Robertsson, Joakim O Blanch, Kurt Nihei, Jeroen TrompAbstract:“Modeling of Seismic Wave propagation is a core component in almost every aspect of exploration seismology, ranging from survey design methods to imaging and inversion algorithms. The last time SEG published a reprint volume on numerical modeling was in 1990. Since then, the last two decades has seen a step change in the application and use of Â"full Wave equationÂ" modeling methods enabled by the tremendous increase in available computational power. Full Waveform inversion, reverse time migration and 3D elastic finitedifference synthetic data generation are examples of modeling applications that are currently having a fundamental impact on our business. In Numerical Modeling of Seismic Wave Propagation: Gridded Two-way Wave-equation Methods, readers will find many of the wellknown and referenced papers from the exploration Seismic community as well as some of the key papers that have impacted other fields of seismology. Because the modeling literature is vast, we have limited the scope of the reprint volume to papers over the last two decades on modeling methods based on the full Wave equation. The reprint volume will be of particular interest to researchers and practitioners interested in modeling methods and their applications. The searchable CD includes the 114-page book of abstracts and the full papers.”
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Forward and adjoint simulations of Seismic Wave propagation on emerging large-scale GPU architectures
SC '12: Proceedings of the International Conference on High Performance Computing Networking Storage and Analysis, 2012Co-Authors: Max Rietmann, Dimitri Komatitsch, Jeroen Tromp, Peter Messmer, Tarje Nissen-meyer, Daniel Peter, Piero Basini, Olaf Schenk, Lapo Boschi, Domenico GiardiniAbstract:Computational seismology is an area of wide sociological and economic impact, ranging from earthquake risk assessment to subsurface imaging and oil and gas exploration. At the core of these simulations is the modeling of Wave propagation in a complex medium. Here we report on the extension of the high-order finite-element Seismic Wave simulation package SPECFEM3D to support the largest scale hybrid and homogeneous supercomputers. Starting from an existing highly tuned MPI code, we migrated to a CUDA version. In order to be of immediate impact to the science mission of computational seismologists, we had to port the entire production package, rather than just individual kernels. One of the challenges in parallelizing finite element codes is the potential for race conditions during the assembly phase. We therefore investigated different methods such as mesh coloring or atomic updates on the GPU. In order to achieve strong scaling, we needed to ensure good overlap of data motion at all levels, including internode and host-accelerator transfers. Finally we carefully tuned the GPU implementation. The new MPI/CUDA solver exhibits excellent scalability and achieves speedup on a node-to-node basis over the carefully tuned equivalent multi-core MPI solver. To demonstrate the performance of both the forward and adjoint functionality, we present two case studies run on the Cray XE6 CPU and Cray XK6 GPU architectures up to 896 nodes: (1) focusing on most commonly used forward simulations, we simulate Seismic Wave propagation generated by earthquakes in Turkey, and (2) testing the most complex Seismic inversion type of the package, we use ambient Seismic noise to image 3-D crust and mantle structure beneath western Europe.
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High-frequency simulations of global Seismic Wave propagation using SPECFEM3D_GLOBE on 62K processors
SC '08: Proceedings of the 2008 ACM IEEE Conference on Supercomputing, 2008Co-Authors: Laura Carrington, Dimitri Komatitsch, Michael Laurenzano, Mustafa M. Tikir, David Michea, Nicolas Le Goff, Allan Snavely, Jeroen TrompAbstract:SPECFEM3D_GLOBE is a spectral element application enabling the simulation of global Seismic Wave propagation in 3D anelastic, anisotropic, rotating and self-gravitating Earth models at unprecedented resolution. A fundamental challenge in global seismology is to model the propagation of Waves with periods between 1 and 2 seconds, the highest frequency signals that can propagate clear across the Earth. These Waves help reveal the 3D structure of the Earth's deep interior and can be compared to seismographic recordings. We broke the 2 second barrier using the 62K processor Ranger system at TACC. Indeed we broke the barrier using just half of Ranger, by reaching a period of 1.84 seconds with sustained 28.7 Tflops on 32K processors. We obtained similar results on the XT4 Franklin system at NERSC and the XT4 Kraken system at University of Tennessee Knoxville, while a similar run on the 28K processor Jaguar system at ORNL, which has better memory bandwidth per processor, sustained 35.7 Tflops (a higher flops rate) with a 1.94 shortest period.Thus we have enabled a powerful new tool for Seismic Wave simulation, one that operates in the same frequency regimes as nature; in seismology there is no need to pursue periods much smaller because higher frequency signals do not propagate across the entire globe.We employed performance modeling methods to identify performance bottlenecks and worked through issues of parallel I/O and scalability. Improved mesh design and numbering results in excellent load balancing and few cache misses. The primary achievements are not just the scalability and high teraflops number, but a historic step towards understanding the physics and chemistry of the Earth's interior at unprecedented resolution.
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Simulations of global Seismic Wave propagation for 3-D Earth model
Proceedings. Seventh International Conference on High Performance Computing and Grid in Asia Pacific Region 2004., 2004Co-Authors: Seiji Tsuboi, Dimitri Komatitsch, Chen Ji, Jeroen TrompAbstract:We use a spectral-element method implemented on the Earth Simulator in Japan to simulate broadband Seismic Waves generated by various earthquakes. The spectral-element method is based on a weak formulation of the equations of motion and has both the flexibility of a finite-element method and the accuracy of a pseudospectral method. The method has been developed on a large PC cluster and optimized on the Earth Simulator. We perform numerical simulation of Seismic Wave propagation for a three-dimensional Earth model, which incorporates 3D variations in compressional Wave velocity, shear-Wave velocity and density, attenuation, anisotropy, ellipticity, topography and bathymetry, and crystal thickness. The simulations are performed on 4056 processors, which require 507 out of 640 nodes of the Earth Simulator. We use a mesh with 206 million spectral-elements, for a total of 13.8 billion global integration grid points (i.e., almost 37 billion degrees of freedom). We show examples of simulations for several large earthquakes and discuss future applications in seismological studies.
Dimitri Komatitsch - One of the best experts on this subject based on the ideXlab platform.
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Modeling of global Seismic Wave propagation on the Earth Simulator
2020Co-Authors: Seiji Tsuboi, Dimitri Komatitsch, Chen Ji, Jeroen TrompAbstract:We use the Earth Simulator to model Seismic Wave propagation resulting from large earthquakes on a global scale. Simulations are conducted based upon the spectral-element method, a high-degree finite- element technique. We include the full complexity of the Earth, i.e., a three-dimensional Seismic Wave veloci- ty and density structure, a 3-D crustal model, the elliptical figure of the Earth as well as topography and bathymetry. We use 507 nodes of the Earth Simulator (4056 processors) and model the three dimensional Earth with 13.7 billion grid points. A total of 7 terabytes of memory is needed. We have reached a vectoriza- tion ratio of 99.3%, and attained a total performance of 10 teraflops (32% of the peak performance). The very high resolution of the mesh allows us to calculate theoretical Seismic Waves for realistic fully three-dimen- sional Earth model, which are accurate at periods of 3.5 seconds and longer. We have modeled Seismic Waves generated by recent large earthquakes and show the importance of including three-dimensional structure in the Seismic Wave simulation. These theoretical seismograms calculated for fully three-dimensional Earth models should improve our understanding of earthquake source mechanisms and the Earth dynamics.
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Forward and adjoint simulations of Seismic Wave propagation on emerging large-scale GPU architectures
SC '12: Proceedings of the International Conference on High Performance Computing Networking Storage and Analysis, 2012Co-Authors: Max Rietmann, Dimitri Komatitsch, Jeroen Tromp, Peter Messmer, Tarje Nissen-meyer, Daniel Peter, Piero Basini, Olaf Schenk, Lapo Boschi, Domenico GiardiniAbstract:Computational seismology is an area of wide sociological and economic impact, ranging from earthquake risk assessment to subsurface imaging and oil and gas exploration. At the core of these simulations is the modeling of Wave propagation in a complex medium. Here we report on the extension of the high-order finite-element Seismic Wave simulation package SPECFEM3D to support the largest scale hybrid and homogeneous supercomputers. Starting from an existing highly tuned MPI code, we migrated to a CUDA version. In order to be of immediate impact to the science mission of computational seismologists, we had to port the entire production package, rather than just individual kernels. One of the challenges in parallelizing finite element codes is the potential for race conditions during the assembly phase. We therefore investigated different methods such as mesh coloring or atomic updates on the GPU. In order to achieve strong scaling, we needed to ensure good overlap of data motion at all levels, including internode and host-accelerator transfers. Finally we carefully tuned the GPU implementation. The new MPI/CUDA solver exhibits excellent scalability and achieves speedup on a node-to-node basis over the carefully tuned equivalent multi-core MPI solver. To demonstrate the performance of both the forward and adjoint functionality, we present two case studies run on the Cray XE6 CPU and Cray XK6 GPU architectures up to 896 nodes: (1) focusing on most commonly used forward simulations, we simulate Seismic Wave propagation generated by earthquakes in Turkey, and (2) testing the most complex Seismic inversion type of the package, we use ambient Seismic noise to image 3-D crust and mantle structure beneath western Europe.
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forward and adjoint simulations of Seismic Wave propagation on fully unstructured hexahedral meshes
Geophysical Journal International, 2011Co-Authors: Daniel Peter, Roland Martin, Dimitri Komatitsch, Nicolas Le Goff, Emanuele Casarotti, Pieyre Le Loher, Federica Magnoni, Celine Blitz, Tarje NissenmeyerAbstract:We present forward and adjoint spectral-element simulations of coupled acoustic and (an)elastic Seismic Wave propagation on fully unstructured hexahedral meshes. Simulations benefit from recent advances in hexahedral meshing, load balancing and software optimization. Meshing may be accomplished using a mesh generation tool kit such as CUBIT, and load balancing is facilitated by graph partitioning based on the SCOTCH library. Coupling between fluid and solid regions is incorporated in a straightforward fashion using domain decomposition. Topography, bathymetry and Moho undulations may be readily included in the mesh, and physical dispersion and attenuation associated with anelasticity are accounted for using a series of standard linear solids. Finite-frequency Fr'echet derivatives are calculated using adjoint methods in both fluid and solid domains. The software is benchmarked for a layercake model. We present various examples of fully unstructured meshes, snapshots of Wavefields and finite-frequency kernels generated by Version 2.0 'Sesame' of our widely used open source spectral-element package SPECFEM3D.
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high order finite element Seismic Wave propagation modeling with mpi on a large gpu cluster
Journal of Computational Physics, 2010Co-Authors: Dimitri Komatitsch, Gordon Erlebacher, Dominik Goddeke, David MicheaAbstract:We implement a high-order finite-element application, which performs the numerical simulation of Seismic Wave propagation resulting for instance from earthquakes at the scale of a continent or from active Seismic acquisition experiments in the oil industry, on a large cluster of NVIDIA Tesla graphics cards using the CUDA programming environment and non-blocking message passing based on MPI. Contrary to many finite-element implementations, ours is implemented successfully in single precision, maximizing the performance of current generation GPUs. We discuss the implementation and optimization of the code and compare it to an existing very optimized implementation in C language and MPI on a classical cluster of CPU nodes. We use mesh coloring to efficiently handle summation operations over degrees of freedom on an unstructured mesh, and non-blocking MPI messages in order to overlap the communications across the network and the data transfer to and from the device via PCIe with calculations on the GPU. We perform a number of numerical tests to validate the single-precision CUDA and MPI implementation and assess its accuracy. We then analyze performance measurements and depending on how the problem is mapped to the reference CPU cluster, we obtain a speedup of 20x or 12x.
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Exploiting Intensive Multithreading for the Efficient Simulation of 3D Seismic Wave Propagation
2008 11th IEEE International Conference on Computational Science and Engineering, 2008Co-Authors: Fabrice Dupros, Dimitri Komatitsch, Hideo Aochi, Ariane Ducellier, Jean RomanAbstract:Parallel computing is widely used for large scale three-dimensional simulation of Seismic Wave propagation. One particularity of most of these simulations is to consider a finite computing domain whereas the physical problem is unbounded. Additional numerical conditions are then required to absorb the energy at the artificial boundaries, which introduces a different formulation and a load-imbalance. In the context of finite difference method, we study the use of thread overloading approach to alleviate the imbalance. We introduce a mixed-hybrid parallel implementation based on a classical cartesian partitioning at the MPI level and a self-scheduling algorithm at the thread level to handle more than 700 threads on 8 processors. We demonstrate the efficiency of our methodology on an example of regional modeling performed on 80 processors.
Geoffrey A. Abers - One of the best experts on this subject based on the ideXlab platform.
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Subduction factory 1. Theoretical mineralogy, densities, Seismic Wave speeds, and H 2 O contents
Journal of Geophysical Research: Solid Earth, 2003Co-Authors: Bradley R. Hacker, Geoffrey A. Abers, Simon M PeacockAbstract:[1] We present a new compilation of physical properties of minerals relevant to subduction zones and new phase diagrams for mid-ocean ridge basalt, lherzolite, depleted lherzolite, harzburgite, and serpentinite. We use these data to calculate H2O content, density and Seismic Wave speeds of subduction zone rocks. These calculations provide a new basis for evaluating the subduction factory, including (1) the presence of hydrous phases and the distribution of H2O within a subduction zone; (2) the densification of the subducting slab and resultant effects on measured gravity and slab shape; and (3) the variations in Seismic Wave speeds resulting from thermal and metamorphic processes at depth. In considering specific examples, we find that for ocean basins worldwide the lower oceanic crust is partially hydrated (< 1.3 wt % H2O), and the uppermost mantle ranges from unhydrated to &SIM;20% serpentinized (&SIM;2.4 wt % H2O). Anhydrous eclogite cannot be distinguished from harzburgite on the basis of Wave speeds, but its &SIM;6% greater density may render it detectable through gravity measurements. Subducted hydrous crust in cold slabs can persist to several gigapascals at Seismic velocities that are several percent slower than the surrounding mantle. Seismic velocities and V-P/V-S ratios indicate that mantle wedges locally reach 60-80% hydration.
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subduction factory 1 theoretical mineralogy densities Seismic Wave speeds and h2o contents
Journal of Geophysical Research, 2003Co-Authors: Bradley R. Hacker, Geoffrey A. Abers, Simon M PeacockAbstract:[1] We present a new compilation of physical properties of minerals relevant to subduction zones and new phase diagrams for mid-ocean ridge basalt, lherzolite, depleted lherzolite, harzburgite, and serpentinite. We use these data to calculate H2O content, density and Seismic Wave speeds of subduction zone rocks. These calculations provide a new basis for evaluating the subduction factory, including (1) the presence of hydrous phases and the distribution of H2O within a subduction zone; (2) the densification of the subducting slab and resultant effects on measured gravity and slab shape; and (3) the variations in Seismic Wave speeds resulting from thermal and metamorphic processes at depth. In considering specific examples, we find that for ocean basins worldwide the lower oceanic crust is partially hydrated (<1.3 wt % H2O), and the uppermost mantle ranges from unhydrated to � 20% serpentinized (� 2.4 wt % H2O). Anhydrous eclogite cannot be distinguished from harzburgite on the basis of Wave speeds, but its � 6% greater density may render it detectable through gravity measurements. Subducted hydrous crust in cold slabs can persist to several gigapascals at Seismic velocities that are several percent slower than the surrounding mantle. Seismic velocities and VP/VS ratios indicate that mantle wedges locally reach 60–80% hydration. INDEX TERMS: 3040 Marine Geology and Geophysics: Plate tectonics (8150, 8155, 8157, 8158); 3660 Mineralogy and Petrology: Metamorphic petrology; 3919 Mineral Physics: Equations of state; 5199 Physical Properties of Rocks: General or miscellaneous; 8123 Tectonophysics: Dynamics, seismotectonics; KEYWORDS: subduction, Seismic velocities, mineral physics, H2O
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subduction factory 1 theoretical mineralogy densities Seismic Wave speeds and h 2 o contents
Journal of Geophysical Research, 2003Co-Authors: Bradley R. Hacker, Geoffrey A. Abers, Simon M PeacockAbstract:[1] We present a new compilation of physical properties of minerals relevant to subduction zones and new phase diagrams for mid-ocean ridge basalt, lherzolite, depleted lherzolite, harzburgite, and serpentinite. We use these data to calculate H2O content, density and Seismic Wave speeds of subduction zone rocks. These calculations provide a new basis for evaluating the subduction factory, including (1) the presence of hydrous phases and the distribution of H2O within a subduction zone; (2) the densification of the subducting slab and resultant effects on measured gravity and slab shape; and (3) the variations in Seismic Wave speeds resulting from thermal and metamorphic processes at depth. In considering specific examples, we find that for ocean basins worldwide the lower oceanic crust is partially hydrated (<1.3 wt % H2O), and the uppermost mantle ranges from unhydrated to � 20% serpentinized (� 2.4 wt % H2O). Anhydrous eclogite cannot be distinguished from harzburgite on the basis of Wave speeds, but its � 6% greater density may render it detectable through gravity measurements. Subducted hydrous crust in cold slabs can persist to several gigapascals at Seismic velocities that are several percent slower than the surrounding mantle. Seismic velocities and VP/VS ratios indicate that mantle wedges locally reach 60–80% hydration. INDEX TERMS: 3040 Marine Geology and Geophysics: Plate tectonics (8150, 8155, 8157, 8158); 3660 Mineralogy and Petrology: Metamorphic petrology; 3919 Mineral Physics: Equations of state; 5199 Physical Properties of Rocks: General or miscellaneous; 8123 Tectonophysics: Dynamics, seismotectonics; KEYWORDS: subduction, Seismic velocities, mineral physics, H2O
