‘Swarm’ of earthquakes rattle south of U.S.-Mexico border. Shaking felt across San Diego

A series of earthquakes struck Baja California just south of the U.S.-Mexico border Sunday and early Monday, with the largest hitting magnitude 4.9 and sending tremors felt across Southern California, according to the U.S. Geological Survey.

The first in the string of earthquakes rattled Sunday just before 10:30 a.m., centered about 20 miles southeast of Mexicali near Delta, Mexico. That magnitude 3.3 earthquake was followed by three more — all weaker than the first — before the 4.9 quake hit at 11:22 a.m., according to USGS.

Over the next 15 hours, almost 30 more earthquakes would be recorded, all in the same Baja California area. Most came in below 4 on the moment magnitude scale, but at least three others measured above 4. The latest one hit Monday just after 2 a.m.

People recorded feeling some weak or light shaking across San Diego County, according to public submissions shared with the USGS.

Despite the number of tremors, no major damage or injuries had been reported as of Monday afternoon.

William Yeck, a research geophysicist with USGS’s National Earthquake Information Center, said the earthquakes followed a relatively common pattern for the region known as earthquake “swarms,” when a series of similar-size seismic events strike one area.

“Swarms are often short-lived but can last months,” Yeck wrote in a statement. It wasn’t clear if the event was over, but the USGS had not recorded any further earthquakes in the area since 2:11 a.m. Monday.

In mid-February, another swarm hit roughly the same area, with more than 20 quakes recorded over a few hours around El Centro, Calif. No major damage was reported then.