SCEC Multi-scale Community Velocity Model TAG

Kim B. Olsen, Evan T. Hirakawa, Te-Yang Yeh, Yehuda Ben-Zion, Clifford H. Thurber, Oliver S. Boyd, & . the SCEC Multi-scale Community Velocity Model TAG Working Group

Submitted August 30, 2026, SCEC Contribution #15646, 2026 SCEC Annual Meeting Poster #TBD

The SCEC Multi-scale Community Velocity Model TAG is centered on the multi-scale P and S seismic velocity models of California and Western Nevada version 1 (MUSCAL) recently developed by Yeh, Ben-Zion and Olsen (2026). MUSCAL was generated by merging and validating nine regional and nine local high-resolution velocity models using 67 Mw4.0-4.8 events throughout California and Western Nevada. The model merging procedure retained only the parts of the models providing superior ground motion prediction efficacy from validation of simulated and recorded ground motions using a ‘fitness’ measure depending on both spectral and time-domain (envelope) metrics. Thus, MUSCAL by design leads to better ground motion prediction accuracy and decreased uncertainty in seismic hazard calculations as compared to the parent model components.

The TAG plans to advance MUSCAL by creating a SCEC workflow and code base for standardized and transparent validation and ingestion of local velocity models. The new workflow will be tested on a number of new available velocity models. We will create a map of the uncertainty of MUSCAL in terms of commonly used intensity measures, which is an important contribution to the uncertainty of the resulting ground motions. We will work toward improving the accuracy of MUSCAL for the San Francisco Bay region using a mix of simulation based and geophysical survey methods with particular emphasis on overlap zones between models, including the Livermore and Concord-Mt. Diablo portion of the East Bay. We will add new seismic data to the combined body-wave and surface-wave data set used by Guo et al. (2025) and explore the use of independent constraints on shallow structure from alternate seismic and non-seismic sources. Finally, we will explore ways to include more accurate anelastic attenuation information into MUSCAL.

Key Words
MUSCAL, Community Velocity Model, Seismic Velocity Model, Ground Motion Simulation, Seismic Hazard

Citation
Olsen, K. B., Hirakawa, E. T., Yeh, T., Ben-Zion, Y., Thurber, C. H., Boyd, O. S., & the SCEC Multi-scale Community Velocity Model TAG Working Group, .. (2026, 08). SCEC Multi-scale Community Velocity Model TAG. Poster Presentation at 2026 SCEC Annual Meeting.

Related Projects & Working Groups
Community Earth Models (CEM)