A CyberShake PSHA Model for Northern California
Date: 4/25/2019
Time: 02:00 PM
Room: Elliott Bay
The Southern California Earthquake Center (SCEC) has developed CyberShake, a software platform which performs 3D physics-based probabilistic seismic hazard analysis (PSHA) using deterministic wave propagation simulations. CyberShake calculations are performed by simulating Strain Green Tensors, then convolving these with slip time histories for hundreds of thousands of individual events from an earthquake rupture forecast. Synthetic seismograms are post-processed to obtain intensity measures, which are combined with event probabilities to produce hazard curves. Typically PSHA results from hundreds of locations are interpolated to produce a regional hazard map.
We have previously used CyberShake to calculate multiple hazard models for Southern and Central California. We have now expanded CyberShake to a large Northern California region which includes the San Francisco Bay Area. PSHA calculations up to 1 Hz for locations of interest in Northern California were performed on the NCSA Blue Waters and OLCF Titan supercomputers as part of CyberShake Study 18.8. To support simulation volumes that included most of California, we tiled three separate 3D community velocity models into a composite statewide model and applied smoothing along interfaces to minimize unrealistic reflections and refractions. To improve the representation of the near-surface velocity structure in the tomographically-derived models, we inserted a geotechnical layer (GTL) in the top 500 meters by applying the Ely (2010) method on Vs30 values from the Wills et al. (2015) map. Tesults from this new region can be combined with previous CyberShake models to produce physics-based PSHA results for much of California.
We will present the unified CyberShake results for all three California regions, with a special emphasis on the new Northern California results. We will compare CyberShake PSHA results to those obtained from GMPEs, investigate the impact of basin structures on hazard, and discuss our future plans.
Presenting Author: Scott Callaghan
Authors
Scott Callaghan scottcal@usc.edu Southern California Earthquake Center, Los Angeles, California, United States Presenting Author
Corresponding Author
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Philip J Maechling maechlin@usc.edu University of Southern California, Los Angeles, California, United States |
Christine A Goulet cgoulet@usc.edu University of Southern California, Los Angeles, California, United States |
Kevin R Milner kmilner@usc.edu University of Southern California, Los Angeles, California, United States |
Mei-Hui Su mei@uscedu.onmicrosoft.com University of Southern California, Los Angeles, California, United States |
Robert W Graves rwgraves@usgs.gov U.S. Geological Survey, Pasadena, California, United States |
Kim B Olsen kbolsen@sdsu.edu San Diego State University, San Diego, California, United States |
Yifeng Cui yfcui@sdsc.edu San Diego State University, San Diego, California, United States |
Brad Aagaard baagaard@usgs.gov U.S. Geological Survey, Menlo Park, California, United States |
Kathryn E Wooddell katie.wooddell@gmail.com University of California, Berkeley, Berkeley, California, United States |
Albert R Kottke arkk@pge.com Pacific Gas and Electric Company, San Francisco, California, United States |
Thomas H Jordan tjordan@usc.edu University of Southern California, Los Angeles, California, United States |
A CyberShake PSHA Model for Northern California
Category
Numerical Modeling of Earthquake Ground Motion, Seismic Noise, Rupture Dynamics and Seismic Wave Propagation