Originally published December 10, 2010 at 10:37 a.m., updated December 10, 2010 at 12:01 p.m.
A mild earthquake rattled the East County highlands this morning, causing no reported structural damage or injuries.
The magnitude-3.9 quake, centered about eight miles northeast of Julian, struck at 10:44 a.m., according to the U.S. Geological Survey.
About 90 minutes earlier, a 3.7-magnitude earthquake shook northern Baja California, about 17 miles southeast of Ocotillo, the federal agency reported.
The shakers followed a 3.9-magnitude earthquake that jostled roughly the same area just south of the U.S.-Mexico border late Wednesday night and a 4.1-magnitude earthquake that hit there early Thursday, according to the USGS.