Strong Earthquake Rattles SoCal, Several Smaller Quakes Follow

EL CENTRO, CA — A magnitude 4.8 earthquake struck early Monday morning near El Centro in Imperial County, east of San Diego, and was followed by a series of other quakes.

The first quake was recorded at 12:36 a.m. about 1.8 miles north-northwest of El Centro, according to the United States Geological Survey. The epicenter of the quake was roughly 11.7 miles deep.

For the next 25 minutes, 12 more 2.5-magnitude or greater quakes were recorded between 12:38 and 1:01 a.m. in the El Centro and Imperial areas of Southern California, according to the USGS. The largest aftershock was a 4.5-magnitude quake that struck at 12:42 a.m. about 1.2 miles northwest of El Centro.

The earthquake swarm continued through the morning. As of 6:35 a.m. Monday, a total of 23 quakes with at least a 2.5-magnitude have rattled the region. The latest earthquake, a magnitude 2.5 quake, struck at 6:34 a.m. a little more than a half-mile southeast of El Centro.

Residents reported feeling the initial quake across San Diego County, including in Alpine, Chula Vista, Coronado, Imperial Beach, La Mesa, Oceanside, Poway and Santee, according to the USGS's "Did You Feel It?" map. The shaking was felt as far away as Palm Desert in Riverside County and Aliso Viejo in Orange County, as well as in Yuma, Arizona.

The earthquake activated the USGS ShakeAlert Earthquake Early Warning System, which detects significant quakes early enough so that alerts can be delivered to residents and automated systems potentially seconds before shaking arrives. The early warning system estimated the quake above magnitude 5.0, so alerts were sent to cell phones through apps such as MyShake and ShakeReadySD, according to the USGS.

As of 7:38 a.m. Monday, the Southern California Seismic Network had recorded 187 "events" in the swarm, with the smallest a 0.9-magnitude quake.

"Many of the smaller events are still being analyzed and will be gradually added to the catalogue," Southern California Seismic Network wrote. "More activity is expected in the next few days. Swarm activity in Southern California can continue for hours, days, weeks, months or years."

There was no tsunami danger from the quakes, according to the National Tsunami Warning Center.

The California Governor's Office of Emergency Services issued a statement Monday that it was closely monitoring the impacts of the earthquake and aftershocks and continues to work with partners to assess any damage.

The earthquake swarm was one of the strongest to hit Southern California in years.

The swarm came just three days after a magnitude 4.6 quake struck near Malibu, which was also followed by a series of smaller quakes.

There were no reports of injuries or damage.

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