Seismologist Dale Grant of the U.S. Geological Survey says the magnitude-5.1 quake struck just before 4 p.m. Saturday. It was centered about 25 miles southeast of Calexico, Calif., and 23 miles southeast of Mexicali, Mexico, at a depth of 6.2 miles.
Several aftershocks followed, the largest a magnitude-4.2 about two hours after the initial quake.
The USGS has received reports of people feeling the quake from 120 miles west of the epicenter in San Diego to 60 miles east in Yuma, Arizona.
Dispatchers with the Calexico Police Department say the station shook briefly but there have been no reports of damage or injuries.
Calexico is a city of about 27,000.