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Kinematics of fault slip associated with the July 4-6 2019 Ridgecrest, Californai earthquakes sequence

July 16, 2020

The 2019 Ridgecrest, California, earthquake sequence produced observable crustal deformation over much of central and southern California, as well as surface rupture over several tens of kilometers. To obtain a detailed picture of the fault slip involved in the 4 July M 6.4 foreshock and 6 July M 7.1 mainshock, we combine strong‐motion seismic waveforms with crustal deformation observations to obtain kinematic and static slip models of both events. We sample the regional seismic wavefield for both the foreshock and mainshock with three‐component records from 31 stations of the California Integrated Seismic Network. The deformation observations include Global Positioning System (GPS), Interferometric Synthetic Aperture Radar (InSAR), and borehole strainmeter recordings of the dynamic strain field. These data collectively constrain the kinematic coseismic slip distributions of the events, with measurements variously observing coseismic slip from one event (e.g., seismic waveforms, kinematic solutions from continuous GPS, and strainmeter time series) or coseismic slip from both events combined (InSAR). We find that the foreshock ruptured two separate faults, one with left‐lateral strike slip on a northeast–southwest‐trending fault and the other with right‐lateral strike slip on an orthogonal fault, with unilateral rupture propagation along both. The mainshock ruptured a series of northwest–southeast‐trending faults with right‐lateral strike slip concentrated in the uppermost 6 km with exceptionally low‐rupture velocity averaging 1.0–1.5  km/s">

Publication Year 2020
Title Kinematics of fault slip associated with the July 4-6 2019 Ridgecrest, Californai earthquakes sequence
DOI 10.1785/0120200018
Authors Fred Pollitz, Jessica R. Murray, Jerry L. Svarc, Charles Wicks, Evelyn Roeloffs, Sarah E. Minson, Katherine Scharer, Katherine J. Kendrick, Kenneth W. Hudnut, Johanna Nevitt, Benjamin A. Brooks, David Mencin
Publication Type Article
Publication Subtype Journal Article
Series Title Bulletin of the Seismological Society of America
Index ID 70247977
Record Source USGS Publications Warehouse
USGS Organization Earthquake Science Center