A swarm of at least 60 earthquakes reaching up to 4.0 magnitude shook the California desert near the Mexican border on Monday night, the U.S. Geological Survey reports.
The other quakes in the swarm ranged from 2.5 to 3.3 magnitude, according to the USGS.
A 20-minute series of quakes, including the 4.0 temblor, began at 6 p.m. Pacific time Monday in the city of El Centro in the Imperial Valley, the USGS reported. More followed over the next several hours, with the most recent striking at 2:04 a.m. Tuesday.
The 11-mile deep 4.0 quake hit at 6:13 p.m., according to the USGS. Hundreds of people, some as far away as Calipatria and Winterhaven, reported feeling the tremor to the agency.
The city of El Centro, which has a population of about 44,000, lies 15 miles northwest of Mexicali, Mexico, KTLA reported.
Many people in Mexicali also reported feeling the 4.0 quake, the USGS reported.
The swarm falls in line with an extension of the Superstition Hills Fault, where a 6.6-magnitude quake struck in 1987, reported seismologist Lucy Jones, according to The Desert Sun.
And two quakes rattled the San Francisco and Monterey bay areas, the USGS reported.
Other quake activity in California includes a 3.3-magnitude tremor near New Idria in San Benito County at 6:40 p.m. Monday and a 3.2-magnitude temblor near Navarro Head west of Ukiah. at 2:44 a.m. Tuesday.
The activity along the coast follows a series of other quakes across the state.
A 3.5-magnitude quake rattled Palm Springs area at 1:44 a.m. Sunday, with several people reporting the roaring quake felt like a truck passing.
In the past 10 days, three 3.0-plus magnitude quakes have been centered in the Ridgecrest area, where two major quakes struck in July, the Los Angeles Times reports.
Swarms of small earthquakes also hit Ventura north of Los Angeles on Thursday and Friday mornings.
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.
Source: Yahoo News