Authors: Elena Marchesini, Takashi Yamamoto, Carlos Rodriguez
Journal: Journal of Seismology and Tectonic Evolution (JSTE), ISSN 3087-4874
Citation: JSTE 1(1), 2024-01-31.
DOI: 10.5281/zenodo.20703192
Type: Original Research
Monitoring temporal variations in seismic velocity provides crucial insights into fault zone healing processes following earthquakes. We apply ambient noise cross-correlation to continuous seismic data from the Southern California Seismic Network over a ten-year period (2010–2020) to measure relative velocity changes (dv/v) in the crust surrounding the San Jacinto and southern San Andreas fault zones. Our results reveal significant long-term velocity increases of up to 0.3% per decade in fault damage zones, with the largest shifts observed along segments that experienced moderate earthquakes (M > 4.5) during the study period. These velocity increases are interpreted as progressive fault healing through fracture closure and cementation, consistent with laboratory estimates of strength recovery. The observed healing rates are spatially heterogeneous and correlate with fault structural maturity, suggesting that mature fault cores heal more slowly. Our findings demonstrate that ambient noise monitoring can resolve decadal-scale healing signals and provide constraints on the time-dependent recovery of fault strength, which is essential for improving seismic hazard models in southern California.
ambient noise tomography, seismic velocity changes, fault zone healing, Southern California, San Jacinto Fault, temporal variations, crustal deformation, fault strength recovery