Searching for Hidden Earthquakes in Southern California
Earthquakes follow a well-known power-law size relation, with smaller events occurring much more often than larger events. Earthquake catalogs are thus dominated by small earthquakes, yet still missing a much larger number of even smaller events caused by signal fidelity issues. To overcome these limitations, we applied a template matching detection technique to the entire waveform archive of the regional seismic network in southern California. This effort resulted in a catalog with 1.81 million earthquakes, a factor of 10 increase, which provides important new insights into the geometry of fault zones at depth, foreshock behavior and nucleation processes, and earthquake triggering mechanisms. The extraordinary detail resolved in this type of catalog will facilitate a new generation of analyses of earthquakes and faults.
Additional Information© 2019 American Association for the Advancement of Science. 16 January 2019; accepted 9 April 2019;. Published online 18 April 2019. The authors thank Robert Crovella of NVIDIA for helping to optimize the CUDA code. The project was greatly facilitated by use of the Caltech HPC facility. Funding: This research was supported by USGS/NEHRP grant G18AP00028; NSF awards: EAR-1550704 & EAR-1818582; by the Southern California Earthquake Center, which is funded by NSF Cooperative Agreement EAR-1033462 and USGS Cooperative Agreement G12AC20038; and by the Los Alamos National Laboratory LDRD program. Author contributions: ZER and EH designed and carried out the initial detection effort; DTT and PMS designed and performed the relocation effort; all authors contributed to the analysis and writing of the manuscript. Authors declare no competing interests. Data and materials availability: The QTM catalog will be publicly available from the Southern California Earthquake Data Center (scedc.caltech.edu). All waveform and parametric data are available from the Caltech/USGS Southern California Seismic Network (33); stored at the Southern California Earthquake Data Center (34). All remaining data are available in the main text or the supplementary materials.
Supplemental Material - aaw6888_Ross_SM.pdf