Waveform-based moment tensor catalog in Southern California using 3D Community Velocity Model

Jiaxuan Li, Zhongwen Zhan, & Xin Wang

Submitted August 11, 2021, SCEC Contribution #11282, 2021 SCEC Annual Meeting Poster #193

Focal mechanisms in Southern California have been routinely determined using a 1D velocity model. However, recent tomography results show strong heterogeneities in the Southern California crust, which may lead to large uncertainties in the moment tensor solutions. In this study, we take advantage of 3D SCEC community velocity models to calculate more precise Green’s functions based on the reciprocity theorem. We have calculated Green’s function database for more than 200 broadband stations using the CVM-S4.26 model through 3D finite-difference modeling in Southern California. Using this database, we developed a highly automatic and near-real-time procedure to determine the moment tensor solutions. We have applied this procedure to more than 1000 small-to-medium-sized earthquakes in Southern California since 1980. Our results show that incorporating the 3D velocity model can refine and complement the existing moment tensor catalogs in the region, resulting in more accurate focal mechanism solutions, focal depth, and moment magnitudes. We can conveniently embed the current procedure into a real-time system for determining future seismic events in the region. We can also transfer it to other areas with good 3D velocity models.

Key Words
Moment Tensor, CVM

Citation
Li, J., Zhan, Z., & Wang, X. (2021, 08). Waveform-based moment tensor catalog in Southern California using 3D Community Velocity Model. Poster Presentation at 2021 SCEC Annual Meeting.


Related Projects & Working Groups
Seismology