SCEC Award Number 20021
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Earthquake moment tensor catalog in the Southern California using SCEC 3D Community Velocity Models
Investigator(s)
Name Organization
Zhongwen Zhan California Institute of Technology
Other Participants Xin Wang
SCEC Priorities 3a, 2d, 4a SCEC Groups Seismology, CXM, CS
Report Due Date 03/15/2021 Date Report Submitted No report submitted
Project Abstract
 Earthquake moment tensor catalog in the Southern California has been routinely processed by the Southern California Earthquake Data Center (SCEDC) using a simple 1D Earth velocity model, which may introduce large uncertainties as the complicated Earth 3D structure effects cannot be adequately quantified. To establish the best practices of earthquake moment tensor catalog in the Southern California, we propose to adopt the Southern California Earthquake Center (SCEC) 3D Community Velocity Models (CVMs) in near-real-time automatic earthquake moment tensor inversion. Our study will result in a new moment tensor catalog for the Southern California region, and provide more accurate moment tensor solutions, focal depths, and moment magnitudes. Our catalog will be available for further seismological and geological investigations, and will contribute to mitigating the seismic hazard and risk in the area.
Intellectual Merit We have developed a highly automated and efficient algorithm to determine the moment tensor solutions for small-to-medium-sized earthquakes using 3D velocity models in the Los Angeles region. Our results show that incorporating the 3D velocity model can refine the existing moment tensor catalogs in the region, resulting in more accurate focal mechanism solutions, focal depth, and moment magnitude. In addition, our highly accurate, efficient, and automatic inversion approach can be expanded in other regions and can be easily implemented in near real-time system.
Broader Impacts The moment tensor catalog we are producing will be the first regional scale catalog produced by full waveform inversions using 3D Green’s functions. The catalog can be used in estimating crustal stress state, fault geometries, and fault damages.
Exemplary Figure Figure 6. Comparison of 66 example focal mechanisms from the 2019 Ridgecrest earthquake sequence between our solution (red), the HASH solution (black), and the SCEDC-CMT solution (blue). These three different solutions are mostly consistent.