3.2 magnitude earthquake strikes near San Diego County after series last week

SAN DIEGO — Another earthquake shook near eastern San Diego County Sunday night, several days after the U.S. Geological Survey reported a series of quakes in the region.

The 3.1 magnitude earthquake struck near Ocotillo, a census-designated place in Imperial County, just before 11 p.m. The tremor had a depth of about 4.5 miles, according to USGS.

As of 7:30 a.m. Monday, no residents reported feeling the quake to the USGS’s “Did You Feel It?” survey. There were also no immediate reports of damage or injuries.

The quake comes after four back-to-back shocks rattled the same area late Thursday to Friday in a likely event that scientists refer to as a “swarm,” which is a series of smaller earthquakes within the span of a few days to a couple weeks.

The largest of the quakes recorded with the swarm reached a 4.8 magnitude at a depth of almost 6 miles in the area east of Ocotillo. This one was felt much farther than others in the series, with some feeling shaking as far west as the San Diego coast.

Areas east of San Diego County are particularly susceptible to these type of one-after-another events, San Diego State University professor of geology emeritus Dr. Pat Abbott told FOX 5 earlier this year after a few earthquake swarms struck the region.

As Abbott explained, the frequent movement is caused by the geothermal energy in the 35-mile stretch of land between the tip of the San Andreas and Imperial faults in the area south of the Salton Sea.

In the area, there is a lot of magma and warm volcanic rocks under the surface. That thermal energy under the surface pumps hot water that creates energy and movement, thus causing earthquake activity.

Sunday’s quake could be a continuation of the earlier swarm, although it is unclear at this time.