Detailed seismic catalog for the San Jacinto fault zone region (2008-2016) from automated processing of raw waveform data

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

Submitted August 7, 2018, SCEC Contribution #8309, 2018 SCEC Annual Meeting Poster #054

We develop an automated processing procedure and apply it to eight years of raw waveform data, amalgamated from five seismic networks operating in the San Jacinto Fault Zone region, to derive an earthquake catalog containing >119, 000 events with approximate magnitude range –1.5 to 5.5. Earthquake locations are determined using separate P and S-wave phase detectors, a probabilistic, global-search 3D location method (NonLinLoc), and a waveform cross-correlation based double-difference relocation method (GrowClust). Local magnitudes are calculated using amplitude measurements from simulated Wood-Anderson instruments. The magnitude of completeness is estimated by the 99th percentile of the Gaussian CDF component of an exponentially-modified Gaussian distribution fit to the entire observed magnitude range using maximum likelihood estimation, and it varies from about 0.9 in a rectangle with dimensions 55 km and 95 km centered on the San Jacinto fault zone, to about 2.0 toward the edges of the study area. The results complement existing catalogs (the Southern California Seismic Network’s standard catalog and its derivatives) with >1.6 times as many events in the focus of the study area. The new detected events are a consequence of increased station density relative to SCSN’s routine processing. The additional seismicity in the new catalog illuminates different seismicity structures with greater detail, compared with other catalogs for the area. Using the catalog earthquakes as templates can increase further significantly the number of events, but the additional events will mainly increase the density of seismicity structures already in the catalog rather than reveal new ones.

Key Words
Earthquake catalog, automated processing, magnitude completeness, San Jacinto Fault Zone, structure

Citation
White, M. C., Ben-Zion, Y., & Vernon, F. L. (2018, 08). Detailed seismic catalog for the San Jacinto fault zone region (2008-2016) from automated processing of raw waveform data. Poster Presentation at 2018 SCEC Annual Meeting.


Related Projects & Working Groups
Seismology