04/07/2021, M3.6 near Trona


  • 07 Apr 2021 06:42:05 PDT, (35.610, -117.410), depth 9.0km.
  • 17km S of Trona, California


  • As of 07 Apr 2021, 07:18AM PDT, there have been no aftershocks recorded.
  • 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 6 events during the 3 days prior to the earthquake (within a 10 km radius).
  • The largest was M1.9 (2021/04/05).

Historical Seismicity

  • Since our records began in 1932 we’ve had 54 events of M4 or greater within 10km of today’s event.
  • The largest historic event was M6.4 on 2019/07/04.
  • The most recent historic event was M4.3 on 08 Jun 2020.


  • CFM fault associations: most likely Eastern Little Lake fault (93%). Alternates: Not associated with a CFM modeled fault (6%), Other CFM faults (1%).*
  • Nearby faults: Garlock fault zone, central Garlock section (5.6 km), Garlock fault zone, central Garlock section (Garlock fault) (10.0 km), Unnamed fault south of Straw Peak (11.2 km), Little Lake fault zone (12.9 km) and Tank Canyon fault (14.9 km).**

Additional Information

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

**Quaternary Fault and Fold Database for the Nation; 2004; FS; 2004-3033; Geological Survey (U.S.), accessed 2021, from USGS web site: https://www.usgs.gov/natural-hazards/earthquake-hazards/faults

This information is subject to change as more up-to-date data become available.

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