Event
- 04 Jul 2019 10:33:48 PDT, (35.705, -117.508), depth 8.7km.
- 12km SW of Searles Valley, California
Aftershocks
- As of 05 Jul 2019, 09:08AM PDT, there have been more than 1,080 aftershocks recorded.
- The largest was M5.4 (smallest M1.2).
- Number ≥ M4: 16
- Number ≥ M3: 105
- Number ≥ M2: 424
- More aftershocks may be expected in the next few days, the largest expected is approximately 1 magnitude unit smaller than the mainshock.
- There is a small chance (about 5%) that a larger quake could occur, with the likelihood decreasing over time.
Possible Foreshocks
- There were 9 events during the 3 days prior to the earthquake (within a 10 km radius).
- The largest was M4.0 (2019/07/04, about 30 minutes prior to the mainshock).
Historical Seismicity
- Since our records began in 1932 we’ve had 31 events of M4 or greater within 10km of today’s event.
- The largest historic event was M5.8 on 1995/09/20.
- The most recent historic event was M4.1 on 01 Nov 2011.
Faults
- CFM fault associations: most likely Not associated with a CFM modeled fault (99%). Alternates: Little Lake fault (1%).*
- Nearby faults: Little Lake fault zone (0.9 km) and Wilson Canyon fault (14.6 km).**
Tectonic Summary
The July 4th, 2019 Mw 6.4 earthquake in eastern California, southwest of Searles Valley, occurred as the result of shallow strike slip faulting in the crust of the North America plate. Focal mechanism solutions for the earthquake indicate rupture occurred on a steeply dipping fault as the result of either right lateral slip on a plane striking NW-SE, or as left lateral slip on a plane striking SW-NE. At the location of this earthquake, approximately 150 km northeast of San Andreas Fault – the major plate boundary in the region – the Pacific plate moves to the northwest with respect to the North America plate at a rate of approximately 48 mm/yr. The location of the earthquake falls within the Eastern California shear zone, a region of distributed faulting associated with motion across the Pacific:North America plate boundary. More detailed studies will be required to precisely identify the causative fault associated with this event.
This region of eastern California has hosted numerous moderate sized earthquakes. Over the past 40 years, 8 other M5+ earthquakes have occurred within 50 km of the July 4th, 2019 earthquake. The largest of these was a M5.8 event on September 20, 1995, about 13 km to the west-northwest of today’s event, which was felt strongly in the China Lake-Ridgecrest area, and more broadly from Los Angeles to Las Vegas. As of 1 hour after the event the July 4th, 2019 earthquake has been followed by numerous aftershocks, the largest of which was a M 4.7 earthquake 2 minutes after the M 6.4 event. Most aftershocks align in a SW-NE trend around the M 6.4 earthquake. The M 6.4 event was also preceded by a series of very small earthquakes over the previous hour, including a M 4.0 event about 30 mins earlier.
Additional Information
- Links for: USGS earthquake page, ShakeMap, DYFI, waveforms.
- Visit our special reports page for further information on local notable earthquakes.
Below are the waveform data associated with this event, as recorded in our Live Seismograms Feed.
*Earthquakes can occur both near or on major known faults, and in places where no clear fault zones are known. Using the statistical method of Evans et al. (in prep. 2019) the location and focal mechanism of this earthquake suggest the above association with modeled faults in the Community Fault Model (CFM) provided by the Southern California Earthquake Center (SCEC) and Harvard University. Note that the CFM fault association may be different from the nearby faults list. Differences may arise due to different fault databases, and because the CFM fault association uses the hypocenter with relation to subsurface 3-dimensional fault orientation models, while the nearby faults list utilizes mapped surface traces as they relate to the epicenter.
CFM Fault: SCEC CFM 5.0 Fault name and closest segment if available; The CFM is maintained by Harvard University, Dept of Earth & Planetary Sciences.
Probability: The probability in percent the earthquake is associated with this fault.
SCSN: Caltech/USGS Southern California Seismic Network
**U.S. Geological Survey and California Geological Survey, 2006, Quaternary fault and fold database for the United States, accessed 2015, from USGS web site: https://earthquake.usgs.gov/hazards/qfaults/
This information is subject to change as more up-to-date data become available.
