A swarm of small earthquakes, the strongest magnitude 4.0, rattled an area of the Imperial Valley near the town of Brawley on Friday, the U.S. Geological Survey reported.
The first of at least 30 quakes occurred at 10:03 a.m., and the sequence intensified several hours later. A 3.5 quake took place at 4:53 p.m., followed by a 3.0 temblor about half an hour later and a 4.0 quake at 7:04 p.m. Between 5 p.m. and 7 p.m., there were 14 separate quakes, but most were too small to be felt or could barely be felt.
All of the quakes were centered one mile southwest of Brawley and were reported at various depths.
Swarms, series of quakes that sometimes last as long as two or three days, are common in the Imperial Valley, one of the state’s most active seismic areas.
No damage was reported from any of the temblors by evening Friday.