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Verification and validation of the broadband CyberShake platform using observations

Scott Callaghan, Christine A. Goulet, Fabio Silva, Philip J. Maechling, Robert W. Graves, Kim B. Olsen, Te-Yang Yeh, Albert R. Kottke, & Yehuda Ben-Zion

Published April 20, 2022, SCEC Contribution #12631

The Southern California Earthquake Center (SCEC) has developed the CyberShake software platform to implement a physics-based probabilistic seismic hazard analysis (PSHA) approach using 3D wave propagation simula- tions to calculate seismograms and ground motions from sources defined in regional earthquake rupture forecasts. CyberShake is able to quantify effects such as basin amplification and rupture directivity that are difficult to capture in conventional empirical ground motion models. Recently, CyberShake has been extended using modules from the SCEC Broadband Platform (BBP) to generate broadband ground motions up to 50 Hz in order to include frequen- cies of engineering interest. Broadband CyberShake has undergone an extensive verification and validation effort against both results from the BBP and data from historical earthquakes, including Northridge, Chino Hills and Landers. For each his- torical event, we ran simulations on the Broadband CyberShake platform, which generates ground motions by combining results from low-frequency (≤1 Hz) deterministic finite difference wave propagation in 1D and 3D media with stochastic high-frequency seismograms (1-50 Hz), for multiple slip realizations and stations. For the verification part of the work, we com- pared the 1D CyberShake ground motions to those computed with the BBP, which uses a frequency-wavenumber code for low-frequency content and a stochastic code for high-frequency content. We found close agreement in 1D simulations between the CyberShake and BBP results, for waveforms, Fourier amplitude spectra and pseudo-spectral accelerations across multiple sites and realizations. We also present comparisons between 3D and 1D Broadband CyberShake results to quantify the impact of the velocity model and basin effects. Finally, we show validation results of the 3D CyberShake ground motions compared against observational data for these events.

Key Words
probabilistic seismic hazard analysis, ground motion simulation, validation

Callaghan, S., Goulet, C. A., Silva, F., Maechling, P. J., Graves, R. W., Olsen, K. B., Yeh, T., Kottke, A. R., & Ben-Zion, Y. (2022, 04). Verification and validation of the broadband CyberShake platform using observations. Oral Presentation at 2022 Seismological Society of America Annual Meeting. https://pubs.geoscienceworld.org/ssa/srl/article/93/2B/1115/612985/2022-Annual-Meeting