Dynamic triggering of earthquakes at Coso and Ridgecrest, California

Yu-Fang Hsu, Xiaofeng Meng, & Yehuda Ben-Zion

Submitted September 7, 2025, SCEC Contribution #14401, 2025 SCEC Annual Meeting Poster #TBD

Dynamic triggering of earthquakes by transient seismic waves from teleseismic and regional events can be used to explore evolving variations in stresses required for fault failure. Systematically investigating stress state variations along faults by monitoring dynamic triggering can improve our understanding of earthquake physics and contribute to earthquake hazard assessment. This study investigates the relations between peak dynamic stress (PDS) of teleseismic and regional events, geothermal production, and statistics of instantaneous/delayed dynamic triggering in the Coso geothermal area and around Ridgecrest. We construct a high-resolution earthquake catalog using refined matched-filter detection from August 2009 to June 2019, just before the July 2019 Ridgecrest sequence, with about 5 times more earthquakes than the catalog of Ross et al. (2019). For robust quantification of seismic rate changes that distinguish remote triggering and local generation of clusters, we use the nearest-neighbor approach for declustering and apply β-analysis only to the background seismicity. We then estimate the PDS from the peak ground velocity of teleseismic and regional events. The results indicate that both geothermal production and background seismicity in Ridgecrest show a general decreasing trend during our study period. The background seismicity rate one year before the 2019 M7.1 Ridgecrest earthquake is significantly below average, consistent with the notion of quiescence. The total potency of instantaneous-triggered events is positively correlated with the PDS. Moreover, clusters of delayed-triggered events are generally larger than clusters with similar mainshock magnitudes that do not have triggered events. However, we do not find a clear threshold for dynamic triggering or any correlation between PDS and β-values. This suggests that, in addition to evolving stress, strength variations play important roles in controlling triggered seismicity.

Citation
Hsu, Y., Meng, X., & Ben-Zion, Y. (2025, 09). Dynamic triggering of earthquakes at Coso and Ridgecrest, California. Poster Presentation at 2025 SCEC Annual Meeting.

Related Projects & Working Groups
Seismology