Probing Seismicity Secrets With Five Nodal Arrays Around the San Jacinto Fault
Description:
Clarifying the relationship between the frequent small earthquakes and the much rarer occurrence of large earthquakes is fundamental to better understanding fault mechanics and earthquake nucleation, but the connection is yet unclear. With more complete catalogs, we can address critical questions to clarify the connection, such as the prevalence and mechanics of foreshocks, the spatial-temporal evolution of swarms, and the fine-scale structure of faults. Although recent advances in template-matching and machine-learning approaches have improved our ability to detect events, the limits of detectability for tiny earthquakes have yet to be reached, and a hidden frontier of microearthquakes remains to be examined. Our recent analysis showed that beamforming applied to a large-N nodal array on the San Jacinto Fault detects about five times more earthquakes than those in the QTM catalog of Ross et al. (2019), which includes many times more events than the standard network catalog. However, locating the events with a single array can be difficult due to the deflection of the incoming waves by heterogeneous velocity structures.
Building on these advances, we deployed five 81-element nodal arrays of 100-m aperture around an active portion of the San Jacinto Fault for four months through February 2025. An array with a 9 by 9 grid of sensors spanning 100 m is practical for efficient installment and maintenance of the equipment and improves signal-to-noise levels to facilitate detection of tiny earthquakes. Template matching, waveform cross-correlation, and differential location techniques applied to multiple arrays enhance our ability to detect and precisely locate tiny earthquakes and provide unprecedented resolution of seismicity and fault structures. This multiple-array project will provide new insights into fault mechanics and seismicity by pushing the limits of microseism detectability. We discuss our preliminary results from this project and its implications for foreshock and swarm properties, such as their prevalence and temporal evolution near the San Jacinto Fault.
Session: New Directions in Environmental, Seismic Hazard and Mineral Resource Exploration Studies [Poster]
Type: Poster
Date: 4/17/2025
Presentation Time: 08:00 AM (local time)
Presenting Author: Taiga
Student Presenter: Yes
Invited Presentation:
Poster Number: 115
Authors
Taiga Morioka Presenting Author Corresponding Author tamorioka@ucsd.edu University of California, San Diego |
Florent Brenguier florent.brenguier@univ-grenoble-alpes.fr University of Grenoble Alpes |
Elizabeth Cochran ecochran@usgs.gov U.S. Geological Survey |
Wenyuan Fan wenyuanfan@ucsd.edu University of California, San Diego |
Quentin Higueret quentin.higueret@univ-grenoble-alpes.fr University of Grenoble Alpes |
Daniel Hollis ddhollis@ucsd.edu University of California, San Diego |
Peter Shearer pshearer@ucsd.edu University of California, San Diego |
Frank Vernon flvernon@ucsd.edu University of California, San Diego |
John Vidale jvidale@usc.edu University of Southern California |
Ruoyan Wang ruoyanw@usc.edu University of Southern California, Los Angeles, California, United States |
Hao Zhang hzhang63@usc.edu University of Southern California, Los Angeles, California, United States |
Probing Seismicity Secrets With Five Nodal Arrays Around the San Jacinto Fault
Category
New Directions in Environmental, Seismic Hazard and Mineral Resource Exploration Studies