Monitoring post-seismic healing process associated with the 2019 Ridgecrest earthquake sequence using ambient seismic noise interferometry

Abstract:

Time-lapse monitoring of seismic velocity changes following large earthquakes can provide insight into fault healing processes. The 2019 magnitude (M) 7.1 Ridgecrest earthquake, California has produced significant peak ground velocity up to ~80 cm/s near the rupture area and ~10 cm/s around the Coso Geothermal Field (CGF). We investigate the recovery process of seismic velocity (dv/v) through the ambient seismic noise interferometry with the high-quality continuous seismic recordings from 17 seismic stations.

Our analysis finds that the sudden dv/v reduction immediately after the M 7.1 Ridgerest mainshock and subsequently dv/v were gradually increased over time. We observe that the co-seismic dv/v exceeds -0.5% and -0.25 % near the rupture area and at the CGF, respectively. We employ a nonlinear least-square inversion to further characterize the temporal behavior of the observed co-seismic velocity changes and post-seismic recovery. Our inversion involves a bootstrap approach to address the uncertainty. The characteristic recovery time is found to range from about 40 days to ~10 years for our target area.