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Title: Toward Exascale Earthquake Ground Motion Simulations for Near-Fault Engineering Analysis

Abstract

Modernizing SW4 for massively parallel time-domain simulations of earthquake ground motions in 3D earth models increases resolution and provides ground motion estimates for critical infrastructure risk evaluations. Simulations of ground motions from large (M ≥ 7.0) earthquakes require domains on the order of 100 to500 km and spatial granularity on the order of 1 to5 m resulting in hundreds of billions of grid points. Surface-focused structured mesh refinement (SMR) allows for more constant grid point per wavelength scaling in typical Earth models, where wavespeeds increase with depth. In fact, MR allows for simulations to double the frequency content relative to a fixed grid calculation on a given resource. The authors report improvements to the SW4 algorithm developed while porting the code to the Cori Phase 2 (Intel Xeon Phi) systems at the National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkeley National Laboratory. As a result, investigations of the performance of the innermost loop of the calculations found that reorganizing the order of operations can improve performance for massive problems.

Authors:
 [1];  [2];  [2];  [1];  [2];  [1]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1399737
Report Number(s):
LLNL-JRNL-731165
Journal ID: ISSN 1521-9615; TRN: US1702849
Grant/Contract Number:
AC52-07NA27344
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Computing in Science and Engineering
Additional Journal Information:
Journal Volume: 19; Journal Issue: 5; Journal ID: ISSN 1521-9615
Publisher:
IEEE
Country of Publication:
United States
Language:
English
Subject:
97 MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; 58 GEOSCIENCES; computational seismology; structural mechanics; earthquake simulations; exascale computing; scientific computing

Citation Formats

Johansen, Hans, Rodgers, Arthur, Petersson, N. Anders, McCallen, David, Sjogreen, Bjorn, and Miah, Mamun. Toward Exascale Earthquake Ground Motion Simulations for Near-Fault Engineering Analysis. United States: N. p., 2017. Web. doi:10.1109/MCSE.2017.3421558.
Johansen, Hans, Rodgers, Arthur, Petersson, N. Anders, McCallen, David, Sjogreen, Bjorn, & Miah, Mamun. Toward Exascale Earthquake Ground Motion Simulations for Near-Fault Engineering Analysis. United States. doi:10.1109/MCSE.2017.3421558.
Johansen, Hans, Rodgers, Arthur, Petersson, N. Anders, McCallen, David, Sjogreen, Bjorn, and Miah, Mamun. 2017. "Toward Exascale Earthquake Ground Motion Simulations for Near-Fault Engineering Analysis". United States. doi:10.1109/MCSE.2017.3421558.
@article{osti_1399737,
title = {Toward Exascale Earthquake Ground Motion Simulations for Near-Fault Engineering Analysis},
author = {Johansen, Hans and Rodgers, Arthur and Petersson, N. Anders and McCallen, David and Sjogreen, Bjorn and Miah, Mamun},
abstractNote = {Modernizing SW4 for massively parallel time-domain simulations of earthquake ground motions in 3D earth models increases resolution and provides ground motion estimates for critical infrastructure risk evaluations. Simulations of ground motions from large (M ≥ 7.0) earthquakes require domains on the order of 100 to500 km and spatial granularity on the order of 1 to5 m resulting in hundreds of billions of grid points. Surface-focused structured mesh refinement (SMR) allows for more constant grid point per wavelength scaling in typical Earth models, where wavespeeds increase with depth. In fact, MR allows for simulations to double the frequency content relative to a fixed grid calculation on a given resource. The authors report improvements to the SW4 algorithm developed while porting the code to the Cori Phase 2 (Intel Xeon Phi) systems at the National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkeley National Laboratory. As a result, investigations of the performance of the innermost loop of the calculations found that reorganizing the order of operations can improve performance for massive problems.},
doi = {10.1109/MCSE.2017.3421558},
journal = {Computing in Science and Engineering},
number = 5,
volume = 19,
place = {United States},
year = 2017,
month = 9
}

Journal Article:
Free Publicly Available Full Text
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  • Near-fault effects have been widely recognised to produce specific features of earthquake ground motion, that cannot be reliably predicted by 1D seismic wave propagation modelling, used as a standard in engineering applications. These features may have a relevant impact on the structural response, especially in the nonlinear range, that is hard to predict and to be put in a design format, due to the scarcity of significant earthquake records and of reliable numerical simulations. In this contribution a pilot study is presented for the evaluation of seismic ground-motions in the near-fault region, based on a high-performance numerical code for 3Dmore » seismic wave propagation analyses, including the seismic fault, the wave propagation path and the near-surface geological or topographical irregularity. For this purpose, the software package GeoELSE is adopted, based on the spectral element method. The set-up of the numerical benchmark of 3D ground motion simulation in the valley of Grenoble (French Alps) is chosen to study the effect of the complex interaction between basin geometry and radiation mechanism on the variability of earthquake ground motion.« less
  • Using the discrete wave number representation method (Bouchon and Aki, 1977; Bouchon, 1979), we model the Parkfield earthquake of 1966 as a Haskell-type dislocation source embedded in a layered medium. We show that the displacement and velocity recorded near the source (station 2 of the Cholame-Shandon array) can be fully accounted for by the propagation of the rupture on the branch of the fault closest to the station. The slip and slip velocity inferred are about 40 cm and 130 cm/s, respectively. The ground motion at the accelerograph site and in the region close to the source was very stronglymore » amplifield by the sedimentary layer. The rupture, after being initiated at depth, stayed buried well under the sediments on the main segment of the fault. The dislocation then jumped across Cholame Valley and became quite shallow. On this southeast branch of the fault the rupture most likely penetrated the sediments. The results obtained constitute an encouraging step toward predicting the strong ground motion at a given site for a potential earthquake fault.« less
  • We present a theoretical study of the ground motion produced by shallow dip slip faults near the source. The earthquake is modeled as a finite three-dimensional dislocation embedded in a layered medium, and the resulting surface displacement is computed at more than a thousand locations distributed all over the source region. By combining together all the seismograms obtained, the time history and spatial dependence of the strong ground motion can be inferred. Calculations are carried out by using for the source geometry the fault plane obtained for the San Fernando earthquake. Various crustal structures are considered. When the medium departsmore » from a homogeneous half space, the ground displacement exhibits a high degree of complexity. This complexity increases when low-velocity layers are present. Two of the major findings of the study are the striking directivity effect of the propagating rupture on the surface motion and the large amplification of horizontal motions by sedimentary layers.« less
  • A theoretical study of the ground motion produced by strike slip faults is presented. The source is modeled as a progagating dislocation embedded in a layered medium. The resulting surface displacement is computed at more than a thousand locations covering the whole near-source region (0--100 km from the source). The seismograms obtained are then combined together to yield the space and time dependence of the ground motion. Various source-medium configurations are studied. The results show the strong directivity effect of the propagating rupture. Large surface displacements and high-frequency motions are confined to a narrow zone around the fault and tomore » the region which extends beyond the source along the trend of the fault. SH waves and Love waves are the dominant contribution to the ground shaking. The vertical displacement is small but exhibits high-frequency oscillatory motions. The presence of low-velocity surface layers has a very severe effect on the amplitude and duration of the ground shaking.« less