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The Southern California Seismic Network Earthquake Catalog: Completeness, Event Quality and Recent Improvements

Description: 

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 900,000 events, with most recorded after the major expansion of the physical seismic network in the 1970s. Recorded events are primarily earthquakes but also include other events, such as quarry blasts and nuclear tests. In addition to an origin time, hypocenter, magnitude, and phase picks, quality parameters such as location errors are also tracked. In this study, we examine how the completeness and event quality of the SCSN catalog has changed over the network’s history, focusing particularly on the past ~20 years. The largest change to nearly all parameters is during the 1970s network expansion, with more gradual improvements in the years since then. Network improvement and densification of key areas during the past 15-20 years have resulted in noticeable decreases in the mean depth error and azimuthal gap, a significant increase in the number of phase picks per event, and tighter distributions of the depth and horizontal errors and azimuthal gap. The current magnitude of completeness for the entire monitored region is around 1, although specific subregions or sequences may be higher or lower. Recent incorporation of machine learning algorithms into our event post-processing has also helped to produce more accurate automatic phase picks and origins before analyst review, and it may be applied to improve unreviewed events in the catalog backlog.

Session: Network Seismology: Recent Developments, Challenges and Lessons Learned [Poster]

Type: Poster

Date: 4/15/2025

Presentation Time: 08:00 AM (local time)

Presenting Author: Ellen

Student Presenter: No

Invited Presentation: 

Poster Number: 32

Authors