SCEC2024 Poster #191: 3D Broadband (0-25 Hz) Ground Motion Simulations for Statewide California

Group A, Poster #191, Ground Motions (GM)

3D Broadband (0-25 Hz) Ground Motion Simulations for Statewide California

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Poster Presentation

2024 SCEC Annual Meeting, Poster #191, SCEC Contribution #13881 VIEW PDF

The SCEC Broadband Platform (BBP) is an essential tool for structural and geotechnical earthquake engineering applications, as well as for probabilistic seismic hazard analysis, with the capability to simulate ground motions up to 25 Hz. The BBP includes computational modules to model earthquake scenarios by combination of physics-based low-frequency ground motion simulations (typically up to 1 Hz) and stochastic high-frequency signals. However, a significant limitation of this approach is the use of 1D velocity models for the low-frequency component, which inadequately captures the complexities introduced by 3D sedimentary basins and complex topography. These factors can significantly influ...ence local peak ground motions and durations, potentially leading to inaccuracies in seismic hazard assessments. To overcome these limitations, we have integrated into the BBP the 3D physics-based ground motion simulation code AWP-ODC with support for topography (O’Reilly et al., 2022), frequency-dependent anelastic attenuation (Withers et al., 2015), and statistical distributions of small-scale heterogeneities (Savran and Olsen, 2016), and extend the physics-based simulations to 2-4 Hz. We extract high-resolution statewide 3D velocity models using the SCEC Unified Community Velocity Model (UCVM, Small et al., 2017, 2022). We first validate the velocity model against recordings of the 1989 Loma Prieta, 2019 Ridgecrest and 1994 Northridge earthquakes in northern California, central and southern California, respectively. Then, we simulate ten M7-7.7 scenario earthquakes in California, combining the 3D deterministic simulations with stochastic signals up to 25 Hz. By comparing these results with Ground Motion Models (GMMs) and 1D synthetic scenarios, we identify and address deficiencies in existing hazard models, and expect to contribute to more accurate and comprehensive seismic hazard assessment across statewide California.
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