A swarm of small earthquakes hit a town near the U.S.-Mexico border Saturday and continued into Sunday.
Dozens of quakes were reported in and around Ocotillo Wells in Imperial County, six of them larger than a magnitude 3, according to the U.S. Geological Survey.
The largest were felt in a scattering of locations in Imperial, San Diego and Riverside counties, according to the USGS.
Seismologist Lucy Jones said on Twitter that the quakes were occurring along the southern end of the San Jacinto fault system. She said the location was not far from the site of the 1987 Superstition Hills quake, which measured 6.6 magnitude.
Earthquake swarms are nothing new to Imperial County, which is one of more seismically active parts of California. Most of the quakes are small, but there also have been destructive ones.
In 1979, a magnitude 6.5 earthquake sent violent shaking into El Centro, injuring 91 and causing so much damage to the concrete Imperial County Services Building that it had to be demolished.
There was major damage to the irrigation system in the Imperial Valley, a desert region that is a prolific producer of salad vegetables during the winter. Levees lining the All-American Canal, which funnels water from the Colorado River, collapsed along an eight-mile stretch.
A magnitude 5.4 temblor hit Brawley in 2012.