Earthquake Near Big Bear Is No Aftershock

A magnitude 4.8 earthquake centered between Lake Arrowhead and Big Bear shook much of Southern California on Wednesday, causing a few cracks in buildings near the epicenter and sending rocks onto highways in some places.

No injuries were reported in the 12:01 p.m. temblor, which scientists at Caltech and the U.S. Geological Survey said was outside the aftershock zone of the 1992 Landers and Big Bear earthquakes and therefore was a separate seismic event. Although it was unrelated to the Jan. 17 Northridge quake, a modest 3.5-magnitude aftershock of the Northridge temblor did occur about nine hours later.

Wednesday’s 4.8 jolt occurred within five miles of the San Andreas Fault, near Running Springs on California 18. Seismologist Lucile M. Jones of the Geological Survey said it was “close enough to be a foreshock” of a large quake on California’s most significant fault, but the probability of such a quake occurring in the next day or so is only 1%.

At the California Highway Patrol station at Running Springs, Sgt. Casey Bos said the earthquake “felt like it was directly beneath me. We got a pretty good jolt.”

He said the CHP office sustained some cosmetic cracks in the wall but no structural damage.

Rocks ranging in size “from baseballs to basketballs” fell onto California 18, the Rim of the World Highway, Bos said. No traffic problems or damage was reported.

Running Springs resident John Karevoll said he was leaning over a kitchen counter, munching on a cheese sandwich, when the earthquake struck and “knocked the food right out of my mouth.”

He said the shaker was remarkable for its sharpness--and brevity.

Jones said the depth of the horizontal, strike-slip earthquake was only three miles, accounting for some of its sharpness. It was felt lightly in Los Angeles, Orange and northern San Diego counties and more heavily in the Inland Empire.