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The Evolving Tidal Sensitivity of the Seismicity Rate in the Decade Before the M7.1 Ridgecrest, Ca 2019 Earthquake

Description: 

Solid Earth and ocean tides cause the oscillatory deformation of the crust and, thus, modulate stress on faults. Such stress modulation should be accompanied by the modulation of seismicity rates but, due to the small amplitudes of tidal stresses, the modulation is usually weak. If detectable, the sensitivity of seismicity rates to the tides is a valuable tool to probe fault state. We analyzed a decade of microseismicity in the Ridgecrest, CA area in the decade preceding the M7.1 2019-07-06 earthquake to study the tidal sensitivity of the seismicity rate and its temporal evolution. We applied a fully automated workflow combining machine learning detectors and template matching to the continuous waveforms to build a rich, high-resolution earthquake catalog. We used this catalog to investigate the modulation of seismicity rates by the tidal Coulomb stress and volumetric strain. Our study shows that seismicity is ubiquitously modulated by the tides and that the area along the M7.1 earthquake rupture shows increasing sensitivity prior to the rupture, starting in 2017.

Session: Earthquake Preparation Across Scales: Reconciling Geophysical Observations With Laboratory and Theory

Type: Oral

Date: 4/20/2023

Presentation Time: 10:45 AM (local time)

Presenting Author: Eric Beauce

Student Presenter: No

Invited Presentation: 

Authors