SCEC2024 Poster #175: Updates to CyberShake Physics-Based PSHA for Northern California

Group A, Poster #175, Ground Motions (GM)

Updates to CyberShake Physics-Based PSHA for Northern California

Scott Callaghan, Philip J. Maechling, Fabio Silva, Christine A. Goulet, Kevin R. Milner, Mei-Hui Su, Xiaofeng Meng, Camilo Ignacio Pinilla Ramos, Kim B. Olsen, Robert W. Graves, Norman A. Abrahamson, Albert R. Kottke, Karan Vahi, Ewa Deelman, Thomas H. Jordan, & Yehuda Ben-Zion

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Poster Presentation

2024 SCEC Annual Meeting, Poster #175, SCEC Contribution #13798 VIEW PDF

The SCEC-developed CyberShake platform performs physics-based probabilistic seismic hazard analysis. CyberShake uses 3D wave propagation simulations with a reciprocal approach to synthesize seismograms, intensity measures, site-specific hazard curves, and regional hazard maps. CyberShake combines low-frequency deterministic simulations (≤1 Hz) with high-frequency stochastic calculations to produce broadband results at frequencies up to 25 Hz, with validation performed using data from historic events.

Building on our broadband Southern California PSHA model produced with CyberShake Study 22.12, we are applying a similar technique to generate a broadband PSHA model for 315 sit...es in the greater San Francisco Bay Area. We have assembled a regional velocity model for this study which includes 1) the superposition of three separate models: the USGS San Francisco Bay region 3D model (v21.1), the CCA-06 Central California tomography-derived model, and a 1D background model; 2) application of a taper to the near-surface velocity structure using the Ely & Jordan approach; and 3) a reduction in minimum Vs to 400 m/s. We have also chosen to exclude of San Andreas events south of the Central California creeping section from the earthquake rupture forecast based on their low contribution to Bay Area hazard. Additionally, we have integrated the calculation of new data products designed to improve the usefulness of the CyberShake model to PSHA users. These include the calculation of vertical component seismograms, a first for CyberShake, and the addition of new intensity measures, including vertical response spectra and period-dependent durations.

We will present preliminary results from our Northern California hazard calculations, including comparisons with GMMs and previous CyberShake studies in this region.
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