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- Title
Temporal Seismic Velocity Variations: Recovery Following From the 2019 M<sub>w</sub> 7.1 Ridgecrest, California Earthquake.
- Authors
Boschelli, Joshua; Moschetti, Morgan P.; Sens‐Schönfelder, Christoph
- Abstract
We investigated seismic velocity changes (dv/v) associated with the 2019 Ridgecrest earthquake sequence with high‐frequency autocorrelations of ambient seismic noise data. Daily autocorrelation functions were computed for the entirety of 2019 and the first quarter of 2020 for broadband stations within the region, including the temporary broadband stations installed during the aftershock deployment. Travel time shifts in the daily autocorrelation functions, relative to the mean autocorrelation waveform, were computed to produce dv/v time series, which are sensitive to the evolving material properties of the shallow crust surrounding the Ridgecrest fault zone (RFZ). A short‐term velocity drop follows the Mw 7.1 earthquake at stations in the vicinity of the rupture surface, while those greater than 50 km away showed no such drop. The maximum, absolute changes in seismic velocity are proportional to the logarithm of distance from the fault rupture and to the peak dynamic strain experienced during the earthquake. Near the areas of the highest coseismic slip within the RFZ, seismic velocities recovered over 3 months. However, in the vicinity of the nearby Garlock fault, where triggered slip manifested, and north of the RFZ, seismic velocities recovered within a month. We interpret the seismic velocity changes and their recovery to be largely due to changes in the physical properties of the shallow crust, such as fault zone damage recovery caused by the earthquake rupture process and in response to the large dynamic stresses of passing seismic waves from the mainshock. Key Points: Seismic velocity changes due to the Mw 7.1 Ridgecrest earthquake have fundamentally altered the area within 30 km of the epicenter of the mainshockThe maximum amplitude of the changes in seismic velocity exhibits strong correlations with log‐distance and with peak dynamic strain suggesting that strong ground motion is among the primary cause of earthquake‐induced seismic velocity changesSeismic velocity recovers asymptotically, approaching stable values between 1 and 3 months after the Mw 7.1 Ridgecrest earthquake
- Subjects
CALIFORNIA; SEISMIC wave velocity; EARTHQUAKES; AUTOCORRELATION (Statistics); MICROSEISMS; FAULT zones
- Publication
Journal of Geophysical Research. Solid Earth, 2021, Vol 126, Issue 4, p1
- ISSN
2169-9313
- Publication type
Article
- DOI
10.1029/2020JB021465