Three-dimensional seismic velocity models for the San Francisco Bay region, California from joint body-wave and surface-wave tomography validated by waveform simulation

JGR Solid Earth
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Abstract

A high-resolution seismic velocity model for both P and S waves is essential for the San Francisco Bay (SFB) region to accurately simulate earthquake ground motions and assess seismic hazards in this high-risk region. We present new three-dimensional P-wave and S-wave velocity (Vp and Vs) models of the SFB region developed using joint tomographic inversion with a rich set of earthquake and active-source body-wave data and ambient-noise surface-wave data. We designed a dynamic balance strategy to effectively balance the contributions of body-wave and surface-wave data during each iteration of the inversion. Owing to the complementary resolution of body-wave and surface-wave data, our new models are significantly improved compared to previous tomographic models. Major geologic features in the SFB region, including low-velocity basins, high-velocity Franciscan Complex, granite, and gabbro rocks, and across-fault velocity contrasts, are imaged in our Vp and Vs models. Compared to the geology-based U.S. Geological Survey velocity model, our new model has better defined structures for some important areas that are of great concern for seismic hazard assessment, such as the Sacramento-San Joaquin Delta, and the 2014 magnitude 6.0 South Napa earthquake area. We validated our model by simulating waveforms for a set of moderate-magnitude earthquakes. The good performance of our model in waveform simulation indicates its potential for improving ground motion simulation and seismic hazard assessment in the SFB region.

Suggested Citation

Guo, H., Taira, T., Nayak, A., Thurber, C., and Hirakawa, E.T., 2025, Three-dimensional seismic velocity models for the San Francisco Bay region, California from joint body-wave and surface-wave tomography validated by waveform simulation: JGR Solid Earth, v. 130, no. 6, e2025JB031377, 26 p., https://doi.org/10.1029/2025JB031377.

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Publication type Article
Publication Subtype Journal Article
Title Three-dimensional seismic velocity models for the San Francisco Bay region, California from joint body-wave and surface-wave tomography validated by waveform simulation
Series title JGR Solid Earth
DOI 10.1029/2025JB031377
Volume 130
Issue 6
Publication Date June 23, 2025
Year Published 2025
Language English
Publisher American Geophysical Union
Contributing office(s) Earthquake Science Center
Description e2025JB031377, 26 p.
Country United States
State California
Other Geospatial San Francisco Bay region
Additional publication details