StEER - M6.4 and M7.1 Ridgecrest, CA Earthquakes on July 4-5, 2019: Preliminary Virtual Reconnaissance Report (PVRR)

A magnitude 6.4 earthquake with a depth of 10.7 km occurred in San Bernardino County, CA on July 4, 2019. The epicenter was located 12 km south west of Searles Valley. On July 5, 2019, a 7.1 magnitude earthquake occurred near the same location and at a depth of 17 km. It is noted that the earthquakes occurred in a fairly remote area in the Mojave Desert region of eastern California. The earthquakes were felt strongly in the China Lake-Ridgecrest area, and more broadly from Los Angeles to Las Vegas. The 6.4 magnitude earthquake was preceded by several foreschocks, and followed by hundreds of aftershocks. The maximum Peak Ground Accelerations (PGA) of the 6.4 and 7.1 magnitude earthquakes were 0.38g and 0.48g, respectively. This report overviews the hazard characteristics of the July 4 and 5, 2019 Ridgecrest, California M 6.4 and M 7.1 earthquakes, the regulatory context and emergency response, the impacts of these earthquakes, and current conditions by collocating publicly-reported information. This Preliminary Virtual Reconnaissance Report (P-VRR) represents the first product of StEER’s larger coordinated response to this event, informing and supporting other research teams seeking to learn from this disaster.