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  • Spatiotemporal Variations of In Situ Vp/Vs Ratios During the 2019 Ridgecrest Earthquake Sequence Suggest Fault Zone Condition Changes
Title: Spatiotemporal Variations of In Situ Vp/Vs Ratios During the 2019 Ridgecrest Earthquake Sequence Suggest Fault Zone Condition Changes
Abstract The 2019 Mw 7.1 Ridgecrest earthquake was the largest event in California over the past 20 years. The earthquake was preceded by a sequence of foreshocks. However, the physical processes leading to the mainshock remain unclear. Here, we image the ratios of compressional (P)‐ to shear (S)‐wave velocity (Vp/Vs) in the fault zones and examine the spatial and temporal evolution of near‐source material properties during the Ridgecrest earthquake sequence. We find that theVp/Vsratios are spatially homogeneous in the rupture zones, indicating a lack of fault‐zone material difference along strike. We identify an anomalously lowVp/Vsratio fault patch near the mainshock hypocenter before its occurrence, which returned to the background value after the earthquake. This lowVp/Vsratio suggests fluid overpressure, which may have facilitated the nucleation of the 2019 Ridgecrest mainshock.  more » « less
Award ID(s):
2022441 2022429
PAR ID:
10535807
Author(s) / Creator(s):
;
Publisher / Repository:
Geophysical Research Letters
Date Published:
Journal Name:
Geophysical Research Letters
Volume:
51
Issue:
10
ISSN:
0094-8276
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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