A detailed automatic 1998-2015 earthquake catalog of the San Jacinto fault zone region

Malcolm C. White, Zachary E. Ross, Frank L. Vernon, & Yehuda Ben-Zion

Submitted August 1, 2016, SCEC Contribution #6432, 2016 SCEC Annual Meeting Poster #174

The Anza (AZ) network has collected continuous seismic data since 1998 focusing on the San Jacinto Fault Zone (SJFZ). Nearby stations of the regional CI network and several deployments (PB, SB and YN) around the SJFZ provide important additional data. We discuss a seismic catalog derived from a virtual SJFZ network combining stations of the above networks. An accurate and consistent catalog extending to low magnitudes is fundamental for many investigations of earthquakes and structures. While analyst reviewed hypocenters produce the most accurate catalogs, the required analyst hours for the large dataset of the virtual SJFZ network is prohibitively high. In addition, analyst reviewed catalogs produced over decades often contain inconsistencies as various analysts inevitably have differing decision making processes and may apply different tools as they become available. An automated procedure can analyze very large data sets and offers a uniformly consistent product. Special care, however, must be taken to ensure that the accuracy of results are reliable and that the level of completeness of the catalog is understood. Any systematic biases must also be understood to effectively use the catalog for further study. Here we develop a detailed earthquake catalog for the region using an automatic workflow that includes the following key processing steps: (i) A newly developed S-wave detection algorithm, (ii) location inversion using a 3D velocity model derived from joint inversion of surface and body waves, and (iii) double-difference relocation algorithm. Hypocenter errors are estimated using a bootstrap resampling method and moment magnitudes are estimated from the low-frequency asymptote of stacked displacement spectra obtained via multi-taper spectral analysis. Example aspects of the catalog will be presented in the meeting.

Key Words
San Jacinto Fault Zone, catalog, S-wave detection

White, M. C., Ross, Z. E., Vernon, F. L., & Ben-Zion, Y. (2016, 08). A detailed automatic 1998-2015 earthquake catalog of the San Jacinto fault zone region. Poster Presentation at 2016 SCEC Annual Meeting.

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