“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.
The earthquakes, ranging from 2.5 to 5.3 magnitude, occurred in Calipatria, just south of Salton Sea along the San Andreas Fault, the USGS map shows.
Calipatria is about 30 miles north of the Mexican border and about 140 miles east of San Diego.
source: cnn.com