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Peter, Daniel
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Peter, Daniel
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- PublicationRestrictedPetascale computing and future breakthroughs in global seismology(2007-02-11)
; ; ; ; ; ; ;Boschi, L.; ETH Zurich ;Ampuero, J.-P.; ETH Zurich ;Peter, D.; ETH Zurich ;Mai, M.; ETH Zurich ;Soldati, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Giardini, D.; ETH Zurich; ; ; ; ; Will the advent of “petascale” computers be relevant to research in global seismic tomography? We illustrate here in detail two possible consequences of the expected leap in computing capability. First, being able to identify larger sets of differently regularized/parameterized solutions in shorter times will allow to evaluate their relative quality by more accurate statistical criteria than in the past. Second, it will become possible to compile large databases of sensitivity kernels, and update them efficiently in a non-linear inversion while iterating towards an optimal solution. We quantify the expected computational cost of the above endeavors, as a function of model resolution, and of the highest considered seismic-wave frequency.232 20 - PublicationRestrictedForward and adjoint simulations of seismic wave propagation on fully unstructured hexahedral meshes(2011)
; ; ; ; ; ; ; ; ; ; ; ; ; ;Peter, D.; Princeton University, Department of Geosciences, 318 Guyot Hall, Princeton, NJ 08544, USA ;Komatitsch, D.; Université de Pau et des Pays de l’Adour, CNRS & INRIA Magique-3D, Laboratoire de Modélisation et d’Imagerie en Géosciences UMR 5212, Avenue de l’Université, 64013 Pau Cedex, France. Institut universitaire de France, 103 boulevard Saint-Michel, 75005 Paris, France ;Luo, Y.; Princeton University, Department of Geosciences, 318 Guyot Hall, Princeton, NJ 08544, USA ;Martin, R.; Université de Pau et des Pays de l’Adour, CNRS & INRIA Magique-3D, Laboratoire de Modélisation et d’Imagerie en Géosciences UMR 5212, Avenue de l’Université, 64013 Pau Cedex, France ;Le Goff, N.; Université de Pau et des Pays de l’Adour, CNRS & INRIA Magique-3D, Laboratoire de Modélisation et d’Imagerie en Géosciences UMR 5212, Avenue de l’Université, 64013 Pau Cedex, France ;Casarotti, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Le Loher, P.; Université de Pau et des Pays de l’Adour, CNRS & INRIA Magique-3D, Laboratoire de Modélisation et d’Imagerie en Géosciences UMR 5212, Avenue de l’Université, 64013 Pau Cedex, France ;Magnoni, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Liu, Q.; Department of Physics, University of Toronto, Ontario, Canada ;Blitz, C.; Université de Pau et des Pays de l’Adour, CNRS & INRIA Magique-3D, Laboratoire de Modélisation et d’Imagerie en Géosciences UMR 5212, Avenue de l’Université, 64013 Pau Cedex, France ;Nissen-Meyer, T.; Institute of Geophysics, ETH Zurich, Sonneggstr. 5, CH-8092 Zurich, Switzerland ;Basini, P.; Institute of Geophysics, ETH Zurich, Sonneggstr. 5, CH-8092 Zurich, Switzerland ;Tromp, J.; Princeton University, Department of Geosciences, 318 Guyot Hall, Princeton, NJ 08544, USA. Princeton University, Program in Applied & Computational Mathematics, Princeton, NJ 08544, USA; ; ; ; ; ; ; ; ; ; ; ; 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 Fre ́chet 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.239 28 - PublicationOpen AccessInvestigating trade-offs in anelastic full-waveform inversions for regional- to global-scale models(2021-12-13)
; ; ; ; ; ; ; ; ; ; ; ; ;; ; The attenuation of seismic signals plays a crucial role in constraining water content, partial melting, and temperature variations in Earth's crust and mantle. That is, improving the resolution of seismic anelastic models is essential for better understanding the Earth's subsurface structure and its dynamics. However, attenuation tomography models are typically less resolved than seismic wavespeed models mainly due to amplitude measurements' complex nature, which are sensitive to scattering/defocusing, anelasticity, source radiation pattern, and scalar moment. Moreover, attenuation affects not only amplitudes but also seismic wavespeeds as it causes physical dispersion. Taking the full 3D complexity of seismic wave propagation into account helps minimizing the bias from ignoring scattering/defocusing effects in classical anelastic models. Many synthetic tests have so far been performed to validate anelastic full-waveform inversions. However, the trade-off between the elastic and anelastic parameters, which may be highlighted more at the global scale because of the sparse data coverage, is not well investigated or understood in a full 3D setup. Our goal is to test the resolution and trade-off between elastic and anelastic parameters by conducting a synthetic full-waveform benchmark targeting an existing global 3D attenuation model and starting from a 1D Q-model. Although we investigate whole mantle inversions down to the CMB together with the crust, our primary focus will be in the upper mantle where the low-Q layer in 1D Q-models located at around 200 km depth causes the main challenge, speci cally in surface-wave propagation. Our measurement period range lies within 50 to 250 s for which the Cowling approximation to self-gravitation in the numerical wave propagation solver SPECFEM3D_GLOBE is still in good agreement. The aim is to assimilate both phase and amplitude pieces of information in our seismic inversions. The anelastic/elastic iterations are performed on PRACE's Marconi100 system, taking advantage of the GPU hardware accelerators. We present our benchmark results which will allow us to re ne strategies for large-scale anelastic inversions.71 34 - PublicationRestrictedSpectral‐Element Simulations of Seismic Waves Generated by the 2009 L’Aquila Earthquake(2014)
; ; ; ; ; ; ; ;Magnoni, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Casarotti, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Michelini, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Piersanti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Komatitsch, D.; LMA, CNRS UPR 7051, Aix‐Marseille University, Centrale Marseille, 13402 Marseille Cedex 20, France ;Peter, D.; Institute of Geophysics, ETH Zurich, NO H1.2, Sonneggstrasse 5, 8092 Zurich, Switzerland ;Tromp, J.; Department of Geosciences and Program in Applied & Computational Mathematics, Princeton University, Princeton, New Jersey 08544; ; ; ; ; ; We adopt a spectral-element method (SEM) to perform numerical simulations of the complex wavefield generated by the 6 April 2009 Mw 6.3 L’Aquila earthquake in central Italy. The mainshock is represented by a finite-fault solution obtained by inverting strong-motion and Global Positioning System data, testing both 1D and 3D wavespeed models for central Italy. Surface topography, attenuation, and the Moho discontinuity are also accommodated. Including these complexities is essential to accurately simulate seismic-wave propagation. Three-component synthetic waveforms are compared to corresponding velocimeter and strong-motion recordings. The results show a favorable match between data and synthetics up to ∼0:5 Hz in a 200 km × 200 km × 60 km model volume, capturing features mainly related to topography or low-wavespeed basins. We construct synthetic peak ground velocity maps that, for the 3D model, are in good agreement with observations, thus providing valuable information for seismic-hazard assessment. Exploiting the SEM in combination with an adjoint method, we calculate finite-frequency kernels for specific seismic arrivals. These kernels capture the volumetric sensitivity associated with the selected waveform and highlight prominent effects of topography on seismic-wave propagation in central Italy.384 54