Swarm of Earthquakes Shakes Salton Sea: Have You Felt Any?

Dozens of earthquakes have hit the Salton Sea over the last two days, with a large swarm continuing into Tuesday, data indicates.

The largest, a pair of magnitude-4.3 quakes that struck at 7:31 a.m. and 8:23 p.m., were among just over 100 events measured at the lake, just south of the Riverside County border.

"We're referring to this as a swarm ... not just one huge event," Jennifer Andrews of the Caltech Seismological Laboratory said on Monday afternoon. "We've recorded just over 100 events since this morning."

And the swarm didn't stop there. Between 5:33 p.m. and 10:52 p.m. Monday, 16 earthquakes with a magnitude greater than 2.5 were recorded on the USGS website, the largest of them a 4.1 magnitude at 8:36 p.m.

Andrews tells Patch that the swarm isn't likely over, as past events have typically lasted two or three days.

"It's occurring in pulses, so we can't say definitively that it's over," she said Tuesday afternoon.

According to the scientist, a "swarm" pattern is different from the typical, larger single event that is preceded and followed by smaller quakes.

"This isn't unusual activity for this area," she told Patch. "It's a relatively active area."

Andrews said it is difficult to estimate the chances of a larger event occurring as the swarm continues, but added that this series of earthquakes is following a similar pattern to 2001 and 2009 swarms in the same area in terms of magnitudes, frequencies and orientation along an axis running from northeast to southwest.

"There is nothing from past storms to indicate these were foreshocks to bigger events," but that possibility cannot be ruled out," Andrews said.

"We never write off the fact that we might have a large quake, but there's nothing unusual abut this swarm," she told Patch.

In 2009, the largest quake in the three-day swarm of about 450 events was a magnitude 4.8, she said.
The depths of the most recent quakes, while slightly deeper than in the earlier swarms, are still relatively shallow, meaning they will be more widely felt, Andrews said.

The 4.8-magnitude quake on March 24, 2009 was the largest recorded event within 10 kilometers of today's swarm since records began in 1932.

– City News Service contributed to this report.