06/05/2021, M5.3 swarm near Calipatria

Last updated June 7th, 2021

Significant Events

  • Largest event: M5.3, 05 Jun 2021 10:55:58 PDT, (33.140, -115.635), depth 5.8km. 11km W of Calipatria, California.
  • As of 07 Jun 2021, 03:30PM PDT, the following event numbers have been recorded in the swarm:
    • M≥5: 1
    • M≥4: 5
    • M≥3: 34
    • M≥2: 292
  • All M5 events recorded:
    • M 5.3 05 Jun 2021 10:55:58 PDT, (33.140, -115.635), 39919392

Swarm Numbers

  • As of 07 Jun 2021, 03:30PM PDT, we have recorded 1004 events in the swarm (within a 20 km radius, and counting 5 days before the largest event). The smallest event is magnitude 0.5. Many of the smaller events are still being analyzed and will be gradually added to the catalogue.
  • More activity is expected in the next few days, swarm activity in Southern California can continue for hours, days, weeks, months or years. For more information on swarms please see our Swarm page.

Historical Seismicity

  • Since our records began in 1932 we’ve had 110 events of M4 or greater within 10km of today’s event.
  • The largest historic event was M6.2 on 1987/11/24.
  • The most recent historic event was M4.0 on 05 Jun 2021.


  • CFM fault associations: most likely Westmorland fault; main segment (94%). Alternates: Not associated with a CFM modeled fault (3%), Other CFM faults (3%).*
  • Nearby faults: San Jacinto fault zone, Superstition Hills section (Lone Tree fault) (13.9 km) and San Jacinto fault zone, Superstition Hills section (Superstition Hills flt) (14.7 km).**

Additional Information

Below are the waveform data associated with the M5.3 event, as recorded in our Live Seismograms Feed. Additional waveform data associated with other M3.5+ events in this swarm will be added at a later date.

*Earthquakes can occur both near or on major known faults, and in places where no clear fault zones are known. Using the statisticalmethod 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.

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