Paul Caruso with the U.S. Geological Survey says the first quake struck at 10:02 a.m. Sunday about three miles north-northwest of Brawley.
It was followed by a 3.4 quake about 90 seconds later in the same area near the southern end of the Salton Sea. Magnitude 2.2 and 2.0 quakes followed within six minutes of the first shock.
In the hour or so after the first earthquakes, at least ten more quakes struck the same approximate epicenter about 16 miles north of El Centro.
A sheriff's dispatcher says there have been no reports of damage or injuries.
Caruso says scientists aren't yet sure what fault the quake cluster was on but they are near the 800-mile San Andreas Fault.