“There have been 152 earthquakes measuring all magnitudes,” said seismologist Paul Caruso, speaking by phone from Golden, Colorado.
Caruso said the area is not heavily populated and that it has been known to have “swarms in the past.”
A CNN crew in Orange County said they did not feel any of the quakes.
Calipatria is about 30 miles north of the Mexican border and about 140 miles east of San Diego.
Two 5.9 magnitude earthquakes struck in the Pacific Ocean around 89 and 98 miles west of the coastal town of Gold Beach, Oregon, after 1 a.m. PT on Friday, the USGS reported.
At least four earthquakes ranging in magnitudes from 3.9 to 5.9 occurred in that area in the previous few hours, according to USGS.