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A high-resolution seismic catalog for the initial 2019 Ridgecrest Earthquake sequence: Foreshocks, aftershocks, and faulting complexity

January 22, 2020

I use template matching and precise relative relocation techniques to develop a high-resolution earthquake catalog for the initial portion of the 2019 Ridgecrest earthquake sequence, from July 4-16, encompassing the foreshock sequence and the first 10+ days of aftershocks following the Mw 7.1 mainshock. Using 13,525 routinely cataloged events as waveform templates, I detect and precisely locate a total of 34,091 events. Precisely located earthquakes reveal numerous cross-cutting fault structures with dominantly perpendicular SW- and NW-strikes. Foreshocks of the Mw 6.4 event appear to align on a NW-striking fault. Aftershocks of the Mw 6.4 event suggest that it further ruptured this NW-striking fault, as well as the SW-striking fault where surface rupture was observed. Finally, aftershocks of the Mw 7.1 show a highly complex distribution, illuminating a primary NW-striking fault zone consistent with surface rupture, but also numerous cross-cutting SW-striking faults. Aftershock relocations suggest that the Mw 7.1 event ruptured adjacent to the previous NW-striking rupture of the Mw 6.4, perhaps activating a subparallel structure southwest of the earlier rupture. Both the NW and SE rupture termini of the Mw 7.1 rupture exhibited multiple-fault branching, with particularly high rates of aftershocks and multiple fault orientations in the dilatational quadrant NE of the NW rupture terminus.

Citation Information

Publication Year 2020
Title A high-resolution seismic catalog for the initial 2019 Ridgecrest Earthquake sequence: Foreshocks, aftershocks, and faulting complexity
DOI 10.1785/0220190309
Authors David R. Shelly
Publication Type Article
Publication Subtype Journal Article
Series Title Seismological Research Letters
Series Number
Index ID 70208093
Record Source USGS Publications Warehouse
USGS Organization Geologic Hazards Science Center

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