Assembling, integrating, and assessing 3D seismic velocity models for California

Clifford H. Thurber

Published September 8, 2024, SCEC Contribution #13696, 2024 SCEC Annual Meeting Poster #019 (PDF)

With the geographic expansion of the Statewide California Earthquake Center (SCEC), there are several existing 3D statewide and northern California seismic velocity models that can be incorporated into the existing Unified Community Velocity Model (UCVM) platform for future use in ground motion simulations. I am currently working on assembling a number of these models and integrating them into several standard formats. Two Vp and Vs models that encompass the entire state are the Lin et al. (2010) statewide models from body-wave tomography and the anisotropic models of Doody et al. (2023) from adjoint tomography. One model that covers all Northern California is by Thurber et al. (2009) from body-wave tomography, but only for Vp. Guo et al. (in prep.) have developed a model for Vp and Vs encompassing the greater San Francisco Bay (SFB) region from joint body wave-surface wave tomography. We will also work with the USGS SFB velocity models (Vp and Vs), as recently updated by Hirakawa and Aagaard (2022). The goal is to provide all these models is four standardized formats: netCDF, GeoCSV, SW4, and SCEC UCVM-compatible. Python tools exist for converting from netCDF to GeoCSV and the reverse, and from simple table files to SW4. UCVM is also capable of handling simple table files. Visualization tools for netCDF are available from EarthScope's Earth Model Consortium, and work is in progress by Scott Marshal on an improved web tool for model visualization of models in the UCVM. The final phase will be comparing wavefield simulations for the SFB region to see which of these models performs best for that region.


References

Doody, C., et al., 2023, CANVAS: An adjoint waveform tomography model of California and Nevada, J. Geophys. Res.: Solid Earth 128, e2023JB027583.
Eberhart‐Phillips, D., et al., 2014, Imaging P and S attenuation in the Sacramento-San Joaquin Delta region, Northern California, Bull. Seism. Soc. Am. 104, 2322-2336.
Hirakawa, E., and B. Aagaard, 2022, Evaluation and updates for the USGS San Francisco Bay Region 3D seismic velocity model in the East and North Bay portions, Bull. Seism. Soc. Am. 112, 2070-2096.
Lin, G., et al., 2010, A California statewide three-dimensional seismic velocity model from both absolute and differential times, Bull. Seism. Soc. Am. 100, 225-240.
Thurber, C., et al., 2009, Regional three-dimensional seismic velocity model of the crust and uppermost mantle of northern California, J. Geophys. Res.: Solid Earth 114, B01304.

Key Words
Velocity models, California, UCVM

Citation
Thurber, C. H. (2024, 09). Assembling, integrating, and assessing 3D seismic velocity models for California. Poster Presentation at 2024 SCEC Annual Meeting.

Related Projects & Working Groups
Seismology