High-Performance Computing Ground Motion Simulations of Large, Damaging Hayward Fault Earthquakes

Artie Rodgers, Lawrence Livermore National Laboratory

Wednesday, August 29, 2018 at 10:30 AM

Building 3, Rambo Auditorium
Brad Aagaard

The Hayward Fault presents significant seismic hazard to the eastern San Francisco Bay Area (the “East Bay”). We report on a high-performance computing (HPC) simulation of strong ground motions for a magnitude (M) 7.0 scenario earthquake on the Hayward Fault resolved to 5 Hz and higher. We computed seismic motions obeying physics-based wave propagation in a regional-scale, three-dimensional (3D) Earth model with surface topography with the SW4 finite difference code. Both plane-layered (one-dimensional, 1D) and 3D earth models were considered, with 3D sub-surface material properties and topography sub-sampled from a 3D model by the USGS. The resulting ground motion intensities (peak ground acceleration and velocity, RotD50 spectral accelerations) are in good agreement with ground motion models (GMM) based on empirical data. Median intensities for sites across the domain are within the reported uncertainties of the Abrahamson et al. (2014) GMM across spectral periods 0.1-10 seconds (frequencies 0.1-10 Hz). The variance of ground motion intensity measurements (GMIM’s) residuals ranges 0.4-0.6 natural log units, representing the site-to-site, within event variability for this single rupture. These results demonstrate that earthquake simulations with fully 3D deterministic wave propagation on world-class HPC platforms provides ground motions consistent with empirical models for frequencies of relevance to engineering analysis.

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