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Updated Broadband Cybershake PSHA Model for Southern California

Description: 

The CyberShake platform, developed by the Southern California Earthquake Center, performs physics-based probabilistic seismic hazard analysis using 3D wave propagation simulations with reciprocity to synthesize seismograms. We have extended CyberShake using modules from the SCEC Broadband Platform (BBP), combining low-frequency deterministic simulations with high-frequency stochastic simulations up to 50 Hz to include a broad range of frequencies of engineering interest. The Broadband CyberShake platform has undergone validation testing using the BBP and data from historic events including Northridge and Landers.

Recently we began our latest Broadband CyberShake campaign, Study 22.12. This study produces broadband seismograms up to 50 Hz for about 625,000 events for each of 335 sites in Southern California. New updates in this study include 1) high-frequency modules from the latest BBP release, v22.4.0; 2) the current version of the Graves & Pitarka rupture generator, v5.5.2, which includes larger correlation between slip and rise time; 3) modifications to the near-surface velocity model to incorporate Vs30 information and reduce large near-surface Vs values outside of basins; 4) sampling variability in rupture velocity; and 5) increased hypocentral sampling resolution. We present low-frequency (≤1 Hz) and broadband (0-50 Hz) results from this study, including comparisons with GMMs and comparisons with previous CyberShake results in this region. We find a general trend of reduced hazard as compared to previous CyberShake studies, and improved spectral continuity in the 1-3 second range compared to previous Broadband CyberShake results.

Session: Future Directions in Physics-based Ground-motion Modeling in Preparation for the Fall 2023 Meeting

Type: Oral

Date: 4/18/2023

Presentation Time: 04:30 PM (local time)

Presenting Author: Scott A. Callaghan

Student Presenter: No

Invited Presentation: 

Authors