A swarm of hundreds of earthquakes reaching up to 5.3 magnitude rattled the Salton Sea in California on Saturday and Sunday, the U.S. Geological Survey reports.

The other quakes in the swarm ranged from under 2.5 to 4.6 magnitude, according to the USGS. More than a dozen have struck since midnight Saturday.

The 5.3-magnitude quake hit 3 miles deep at 10:55 a.m. Pacific time Saturday, according to the USGS. Scores of people, some as far away as San Francisco and Arizona, reported feeling the tremor to the agency.

It followed several quakes in the 4.0 range in the previous 10 minutes. Dozens of tremors followed the larger quake.

“Today’s swarm is not close enough to the San Andreas fault to raise concern,” seismologist Lucy Jones wrote on Twitter.

Jones also wrote on Twitter that swarms of quakes are common in the Imperial Valley and said this swarm appeared to be petering out.

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Magnitude measures the energy released at the source of the earthquake, the U.S. Geological Survey says. It replaces the old Richter scale.

Quakes between 2.5 and 5.4 magnitude are often felt but rarely cause much damage, according to Michigan Tech.

The Salton Sea in Southern California near the Arizona border is one of the world’s largest inland seas and one of the lowest spots on Earth at 277 feet below sea level.