• Largest event: M4.8, 12 Feb 2024 00:36:25 PST, (32.813, -115.573), depth 17.9km. 3km NNW of El Centro, California.
• As of 13 Feb 2024, 12:35PM PST, the following event numbers have been recorded in the swarm:
• M≥4: 3
• M≥3: 13
• M≥2: 60
• All M4 events recorded:
• M 4.8 12 Feb 2024 00:36:25 PST, (32.813, -115.573), 40666288
• M 4.1 12 Feb 2024 00:38:34 PST, (32.817, -115.587), 40666320
• M 4.6 12 Feb 2024 00:42:48 PST, (32.800, -115.565), 40666368

Swarm Numbers

• As of 13 Feb 2024, 12:35PM PST, we have recorded 232 events in the swarm (within a 20 km radius, and counting 5 days before the largest event). The smallest event is magnitude 0.8. 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 75 events of M4 or greater within 10km of today’s event.
• The largest historic event was M6.9 on 1940/05/19.
• The most recent historic event was M4.1 on 29 Apr 2023.

Faults

• CFM fault associations: most likely Not associated with a CFM modeled fault (54%). Alternates: Weinert El Centro fault (14%), Other CFM faults (32%).*
• Nearby faults: San Jacinto fault zone, Superstition Hills section (Wienert fault) (3.9 km), Imperial fault (6.4 km), Brawley seismic zone (8.0 km), Brawley seismic zone (Brawley fault zone) (8.9 km) and San Jacinto fault zone, Superstition Hills section (Superstition Hills flt) (11.8 km).**

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.

• Largest event: M3.7, 19 Apr 2022 13:30:08 PDT, (32.910, -115.513), depth 15.6km. 8km SSE of Brawley, California.
• As of 21 Apr 2022, 12:34PM PDT, the following event numbers have been recorded in the swarm:
• M≥3: 6
• M≥2: 26
• All M3 events recorded:
• M 3.6 19 Apr 2022 13:22:41 PDT, (32.910, -115.515), 40241424
• M 3.7 19 Apr 2022 13:30:08 PDT, (32.910, -115.513), 40241440
• M 3.3 19 Apr 2022 20:56:46 PDT, (32.915, -115.517), 40241816
• M 3.4 19 Apr 2022 22:19:44 PDT, (32.917, -115.510), 40241880
• M 3.3 20 Apr 2022 16:52:47 PDT, (32.917, -115.513), 40242720
• M 3.6 21 Apr 2022 11:58:50 PDT, (32.892, -115.513), 40243288

Swarm Numbers

• As of 21 Apr 2022, 12:34PM PDT, we have recorded 60 events in the swarm (within a 20 km radius, and counting 5 days before the largest event). The smallest event is magnitude 1.2. 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 114 events of M4 or greater within 10km of today’s event.
• The largest historic event was M6.9 on 1940/05/19.
• The most recent historic event was M4.0 on 01 Oct 2020.

Faults

• CFM fault associations: most likely Imperial fault; Edip segment (38%). Alternates: Not associated with a CFM modeled fault (14%), Other CFM faults (48%).*
• Nearby faults: Imperial fault (2.5 km), Brawley seismic zone (Brawley fault zone) (3.1 km), Brawley seismic zone (4.9 km), San Jacinto fault zone, Superstition Hills section (Wienert fault) (12.6 km) and San Jacinto fault zone, Superstition Hills section (Superstition Hills flt) (13.8 km).**

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.

Summary

Swarms of small magnitude events are relatively common in this area, extending from Riverside to Chino. Based on past historic recordings this swarm is only expected to generate events of magnitude less than 4.0. The swarm falls within the northeast trending Fontana Seismicity Trend, which has no major mapped fault but relatively abundant small seismicity indicating a local network of small fractures and faults. Earthquakes in this area are probably related to the tectonic loading of the nearby San Jacinto and San Andreas faults.

Events

• Current swarm started 2019/05/25 and SCSN has recorded over 1,180 events so far (2019/07/02 4:30pm).
• Largest event so far: M3.2, 02 Jun 2019 16:36:36 PDT, 5km NNW of Glen Avon, California (34.053, -117.500), depth 2.5km.
• Number of events M2-M3: 53 (as of 2019/07/02 4:30pm)
• Number of events M≥3: 5 (as of 2019/07/02 4:30pm)
• M3.1 01 Jun 2019 19:19:48 PDT
• M3.2 02 Jun 2019 16:36:36 PDT
• M3.2 05 Jun 2019 17:20:57 PDT
• M3.0 13 Jun 2019 19:16:07 PDT
• M3.0 16 Jun 2019 17:12:01 PDT



• Events are relatively shallow for southern California, contributing to several of them being felt.
• Earthquake swarms are characterised as clusters of events in space and time that have no obvious mainshock. See this page for further information on southern California swarms.

Historical Seismicity

• Previous swarms in this area: swarms in this area have been recorded back through the 1980s, when our instrumentation network became sensitive enough to detect these smaller events. Swarms containing fewer events (between 50 and 100) were recorded in February and March 2019 along the same fracture, slightly to the NE.
• Since our records began in 1932 we’ve had 18 events of M4 or greater within 10km of today’s event. Most of these events above M4 lie on or near the major adjacent faults: the San Jacinto and San Andreas.

Faults

• CFM fault associations: most likely Fontana Seismicity lineament (89.9%). Alternates: Not associated with a CFM modeled fault (10.1%).*
• Nearby faults: Red Hill-Etiwanda Avenue fault (10.7 km), Red Hill-Etiwanda Avenue fault (Etiwanda Avenue fault) (10.9 km), Sierra Madre fault zone, Cucamonga section (Cucamonga fault) (11.9 km) and San Jacinto fault zone, San Bernardino section (San Jacinto fault) (15.4 km).**

Additional Information

• Links for: USGS earthquake page, ShakeMap, DYFI, waveforms.
• Visit our special reports page for further information on local notable earthquakes.

Below is a video depicting the emergence of the 2019 Glen Avon earthquake swarm through time from May 19, 2019 through to June 6, 2019. Markers are scaled to depict relative magnitude.

Click on Glen Avon KMZ to download the .kmz and run this visualization yourself in Google Earth. (Unzip the file and drag/import it into an open Google Earth window.) Earthquakes included are scaled based on magnitude and are clickable to display a tooltip with the date, magnitude, location, and depth of each earthquake. The data displayed can be acquired at scedc.caltech.edu.

Below are the waveform data associated with this swarm, as recorded in our Live Seismograms Feed for events of magnitude 3.0 and higher. Note that for some of the events, small foreshocks can be seen shortly before the main events listed in the title.