Updates and Evaluations of the Southern California Regional Earthquake Catalog and Related Products

Gabrielle Tepp, Ellen Yu, Aparna Bhaskaran, Ryan Tam, Shang-Lin Chen, Erika Jaski, Yijian Zhou, & Ettore Biondi

Submitted August 30, 2026, SCEC Contribution #15610, 2026 SCEC Annual Meeting Poster #TBD

Since 1932, the Southern California Seismic Network (SCSN) has been maintaining a manually-reviewed earthquake catalog for Southern California as the regional earthquake authority. The catalog now contains over 1,000,000 seismic events. Recorded events are primarily local earthquakes (~875,000) but also include other seismic sources, such as quarry blasts and nuclear tests. Over the past 3 years, we’ve implemented machine-learning algorithms and distributed acoustic sensing (DAS) into our monitoring tools and catalog production workflows. We show some of the effects these have had on the SCSN catalog, such as improved automatic locations. We have also recently added the capacity to quickly produce double-difference relocated catalogs after notable sequences and swarms. This is in addition to the unofficial Hauksson relocated catalog, which was last updated in Feb 2026 along with the associated focal mechanism catalog. Another current project aims to build a near-real-time machine-learning catalog that will be available to researchers via the SCEDC website. Finally, we also share some of the results from a survey that we conducted to evaluate the research community’s needs and desires regarding waveform data and earthquake catalogs in Southern California.

Key Words
earthquake catalog, machine learning, DAS

Citation
Tepp, G., Yu, E., Bhaskaran, A., Tam, R., Chen, S., Jaski, E., Zhou, Y., & Biondi, E. (2026, 08). Updates and Evaluations of the Southern California Regional Earthquake Catalog and Related Products. Poster Presentation at 2026 SCEC Annual Meeting.

Related Projects & Working Groups
Seismology