Swarm of earthquakes shakes Salton Sea area

Earthquake map shows the site of the Aug. 10 4.6 Brawley earthquake.
A magnitude 4.6 earthquake was reported at 8:56 a.m. 19 miles from Brawley, Calif.
(U.S. Geological Survey)

A swarm of mostly small earthquakes on Monday struck the Salton Sea area, one of the most seismically active areas of California.

The largest was a magnitude 4.6 quake reported at 8:56 a.m. 19 miles from Brawley, according to the U.S. Geological Survey. It was among a series of quakes that began at 6:33 a.m. with a magnitude 3.2 earthquake.

More than a dozen temblors followed, one measuring 4.0 and several in the 3 range.

Quake swarms are fairly common in this region, with some producing more than 1,000 small temblors.


Scientists are carefully monitoring the series of quakes, as they are centered at the southern tip of the dangerous San Andreas fault. There is concern the swarm could trigger a larger event, a phenomenon that has occurred in that region in the past.

Neil Driscoll, a geophysicist at UC San Diego’s Scripps Institution of Oceanography, pointed to a chain reaction that occurred in November 1987 when a 6.2 quake on the Elmore Ranch fault near the Salton Sea triggered a 6.6 temblor just over 11 hours later on the Superstition Hills fault. Both quakes were widely felt in San Diego County.

“We have had many swarms in that area over the years, and there has been no triggering of a fault, but we’re watching this closely,” said Driscoll. “We can’t say whether it is or isn’t going to trigger a larger earthquake.”

Did you feel these earthquake? Consider reporting what you felt to the USGS.

Even if you didn’t feel this small earthquake, you never know when the Big One is going to strike. Ready yourself by following our five-step earthquake preparedness guide and building your own emergency kit.

This story was automatically generated by Quakebot, a computer application that monitors the latest earthquakes detected by the USGS. A Times editor reviewed the post before it was published. If you’re interested in learning more about the system, visit our list of frequently asked questions.


San Diego Union-Tribune staff writer Gary Robbins contributed to this report.