Toward Exascale Earthquake Ground Motion Simulations With SW4: Mw 7.0 Hayward Fault Resolved 0-10 Hz
Session: Physics-Based Earthquake Rupture Modeling and Strong Motion Simulations I
Type: Oral
Date: 4/22/2021
Presentation Time: 03:00 PM Pacific
Description:
Numerical simulations of ground motions accounting for seismic wave excitation and propagation in fully three-dimensional (3D) Earth models provide a valuable constraint on the damaging effects of large earthquake where the available empirical data is extremely limited. Recent advances in numerical and computational methods to simulate ground motions on modern graphics-processing unit (GPU) platforms enable higher resolution results in shorter run times. We are running SW4 on GPU platforms to resolve ground motions from large (Mw 7.0-7.5) earthquakes representing static displacements to frequencies of 10 Hz. This presentation reports several important improvements to the SW4 3D summation-by-parts finite difference code. SW4 now supports refinement of the topography conforming curvilinear mesh to coarsen the grid spacing with depth and greatly improve the memory efficiency. This results in more than a 3x reduction in the total number of grid points needed for typical simulations in our study area - the San Francisco Bay Area. We have improved input/output to run large problems on massively parallel systems. This involves using HDF5 structured data files to represent finely sampled Earth and rupture models and efficiently render material properties and sources on the mesh across many processes. For output, SW4 now writes time-series in HDF5 with optional downsampling. These new features have been exercised in an Mw 7.0 Hayward Fault rupture resolving motions 0-10 Hz at regional scale. We ran two simulations of the same rupture with different minimum shear wavespeed, vsmin of 500 and 250 m/s resolving up to 10 or 5 Hz, respectively, each taking about 7 hours on ¼ of the Summit platform. Results inform what is missed by assuming a higher vsmin than is known to be present in the shallow sub-surface. This research was support by the DOE Exascale Computing project EQSIM, the Summit computer access from the Oak Ridge Leadership Computing Facility is gratefully acknowledged.
Presenting Author: Arthur J. Rodgers
Student Presenter: No
Authors
Arthur Rodgers Presenting Author Corresponding Author rodgers7@llnl.gov Lawrence Livermore National Laboratory |
Ramesh Pankajakshan pankajakshan1@llnl.gov Lawrence Livermore National Laboratory |
Bjorn Sjogreen sjogreen2@llnl.gov Lawrence Livermore National Laboratory |
Houjun Tang htang4@lbl.gov Lawrence Berkeley National Laboratory |
Anders Petersson andersp@llnl.gov Lawrence Livermore National Laboratory |
Arben Pitarka pitarka1@llnl.gov Lawrence Livermore National Laboratory |
David McCallen dmccallen@unr.edu University of Nevada |
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Toward Exascale Earthquake Ground Motion Simulations With SW4: Mw 7.0 Hayward Fault Resolved 0-10 Hz
Category
Physics-based Earthquake Rupture Modeling and Strong Motion Simulations