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

The Statewide California Earthquake Center (SCEC) Broadband Platform (BBP) is an important 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 models scenario earthquakes by a combination of physics-based ground motion simulations at low frequencies (typically up to 1 Hz) and stochastic signals for higher frequencies. However, a notable limitation of this approach is the use of 1D velocity models for the low-frequency component, which do not capture the complexities introduced by 3D sedimentary basins and complex topography. These factors may significantly influence 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), statistical distributions of small-scale heterogeneities (Savran and Olsen, 2016) and extended the physics-based simulations' maximum frequency to 2 Hz. We extract 3D velocity models for California using the SCEC Unified Community Velocity Model (UCVM) and compare ground motion predictions from 1D and 3D simulations to Ground Motion Models and recordings of the 1989 Loma Prieta, 2019 Ridgecrest and 1994 Northridge earthquakes in northern, central and southern California, respectively. Then, we simulate a series of M7-7.7 scenario earthquakes in California, combining the 3D deterministic simulations with stochastic signals up to 25 Hz. The results will identify and quantify deficiencies in existing hazard models and are expected to contribute to more accurate and comprehensive seismic hazard assessment across California.

Session: Accuracy and Variability of Physics-based Ground Motion Modeling - II

Type: Oral

Room: Key Ballroom 11

Date: 4/15/2025

Presentation Time: 04:45 PM (local time)

Presenting Author: Ke Xu

Student Presenter: Yes

Invited Presentation: 

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