There were no immediate reports of damages or injuries.
A tsunami warning was put into effect for Costa Rica, Nicaragua, El Salvador, Honduras, Guatemala, Panama and Mexico after the quake struck at 10:37 p.m. Sunday. The warning was later rescinded.
David Walsh, an oceanographer with the Pacific Tsunami Center in Ewa Beach, Hawaii, said a minor, 10-centimeter (3.94-inche) tsunami was registered off Acajutla, El Salvador.
The quake was located 86 miles (138 kilometers) south-southwest of San Miguel, the U.S. Geological Survey reported on its web site. The temblor took place at a depth of 32.9 miles (53 kilometers). The second quake registered about an hour later in the same area at a depth of 35.9 miles (57.8 km).
Alfonso Lara, a technician with El Salvador's Civil Protection agency said authorities were alerted to the threat of a tsunami. "We are doing a general monitoring of the entire coast through our technicians and representatives," he said.
On Sunday, dozens of small to moderate earthquakes struck southeastern California, knocking trailer homes off their foundations and shattering windows in a small farming town east of San Diego. The largest quake registered at a magnitude 5.5 and was centered about three miles (five kilometers) northwest of the town of Brawley, according to the USGS. Another quake about an hour and a half earlier registered at magnitude 5.3. No injuries were reported.