SCEC Award Number 16226 View PDF
Proposal Category Collaborative Proposal (Integration and Theory)
Proposal Title Development and validation of an improved seismic velocity model for the San Jacinto fault region
Investigator(s)
Name Organization
Clifford Thurber University of Wisconsin, Madison Amir Allam University of Utah
Other Participants Xiangfang Zeng (UW post-doc)
Bethany Vanderhoof (UW undergraduste)
Utah undergraduate TBD
SCEC Priorities 4a, 4c, 6c SCEC Groups Seismology, USR, CS
Report Due Date 03/15/2017 Date Report Submitted 03/15/2017
Project Abstract
 We have carried out a multi-faceted effort to improve the three-dimensional (3D) seismic velocity model for the region encompassing the San Jacinto fault zone (SJFZ) (Figure 1). P- and S-wave seismic velocity models have previously been determined for this region from separate inversions of body-wave arrival times by Allam and Ben-Zion (2012) for Vp and Vs and surface-wave dispersion data (from ambient noise) by Zigone et al. (2014) for Vs. These studies provided a starting point for our SCEC-supported work. The tasks that have been carried out consist of the following: (1) apply an effective automatic S-wave picker to an enlarged SJFZ waveform data set to provide data to further improve the sampling of the Vs structure; (2) develop ambient-noise surface-wave measurements at shorter and longer periods to provide increased constraint on the shallower and deeper structure, respectively, in the SJFZ region; (3) carry out joint body wave-surface wave inversions, including the addition of a substantial set of P-wave travel times from explosions to the earthquake dataset; (4) assess the validity of joint inversion models compared to the SCEC models by forward-modeling full-waveform data for a selected earthquakes.
Intellectual Merit Our work illustrates an effective approach to improving the SCEC CVM for the SJFZ area and surrounding region. We have successfully applied a joint inversion technique that may be particularly effective for improving the resolution of shallow structure for both Vp and Vs.
Broader Impacts The project has provided support for early career investigators and undergraduate students, one of whom is female.
Exemplary Figure Figure 6b

Horizontal slices through our new model for (top) Vp and (bottom) Vs at 3, 7, 11, and 16 km depth. Velocities in km/s.