A magnitude 4 earthquake shook Southern California before dawn Sunday morning – the strongest in a series of modest earthquakes near Ontario International Airport over the past month.
Sunday’s 3:51 a.m. earthquake was the fifth of magnitude 3 or greater detected in Ontario since early September, according to the U.S. Geological Survey.
“Moderate” shaking was felt in areas closest to the epicenter, the USGS said, as defined by the modified Mercalli intensity scale. It’s loud enough to wake many people. “Weak” or “light” shaking may have been felt across a wide area, including the most populated parts of San Bernardino and Riverside counties, large swaths of Los Angeles and Orange counties, and parts of San Diego County.
People reported feeling the earthquake from Palmdale to San Diego. The USGS asked people to submit reports on the type of shaking they may have felt – or not felt – during the Did You Feel It? website.
Through Sunday, the strongest earthquake in the past month to hit San Bernardino County’s fourth-most populous city occurred on Sept. 7, when a 3.9-magnitude quake caused “light” tremors near the epicenter. Slight shaking is enough to disrupt windows and dishes and can significantly disrupt stationary cars.
The epicenter of Sunday’s earthquake was centered about a third of a mile southeast of where Highway 60 meets Archibald Avenue. It is approximately 500 feet south of Mountain View Elementary School and a half-mile east of Whispering Lakes Golf Course.
The USGS said its ShakeAlert earthquake early warning system had been activated. People can download the earthquake early warning app for free at myshake.berkeley.edu.
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