Mammoth Area Hit by Quake Swarm

MAMMOTH LAKES, Calif. — A swarm of earthquakes--the largest with a preliminary magnitude of 4.8--shook the Mammoth Lakes area Sunday afternoon, but no damage or injuries were reported, authorities said.

More than 40 temblors of magnitude 2.0 or above rattled the quake-prone mountain area Sunday, but only three measured more than 3.0, according to the U.S. Geological Survey’s Internet site.

A magnitude 3.1 quake at 1:14 p.m. was centered two miles east-southeast of town and was followed three minutes later by a 4.8 magnitude temblor that was centered a mile southeast of town. A magnitude 3.0 quake was recorded at 1:26 p.m. two miles southeast of Mammoth Lakes, according to the Geological Survey.

The area has been hit by a series of upswings in seismic activity.

Scientists aren’t sure precisely what is occurring in the ground except that something is exerting pressure on the resurgent dome and possibly pressing on fluid-filled rocks, causing cracks in them to give way in small earthquakes.