By Jeff Ristine
UNION-TRIBUNE STAFF WRITER

February 23, 2002

There were dizzy spells but no apparent damage yesterday from a magnitude-5.7 earthquake that was felt across San Diego County and Southern California.

The 11:32 a.m. tremor was centered in the Mexican desert, 29 miles south-southeast of Calexico, according to seismologists in the U.S. Geological Survey office at the California Institute of Technology.

The earthquake was initially reported as having a magnitude of 5.2. Nick Scheckel, a seismic analyst at the Caltech Seismology Lab, said it was upgraded to magnitude 5.7 as additional readings were received.

"This is probably the largest earthquake that we've seen down there since 1987," Scheckel said.

Weak to light shaking was felt throughout most of San Diego County.

In Descanso, Carlos Davalos was sitting at a desk when he felt two jolts. On the second one, a small figurine was knocked off a nearby shelf.

"We really got good movement here on that one," said Davalos.

However, the biggest jolts were in Brawley, Calexico and Mexicali.

In Mexicali, government workers were evacuated from the state's civic center complex. Some schools and hospitals also were evacuated. Damage was reported at a number of schools in Mexicali and at the city's General Hospital.

No injuries or damage were reported in Tijuana, Ensenada, Tecate and Rosarito Beach, although in some cases people were evacuated from government offices and tall buildings.

"It was a real strong impact, forward and backward," said Frank Flores, a manager at the Super Shopping Apple Market in Calexico. "After that it started shaking really bad."

A few items on the grocery store's shelves toppled to the floor, said Flores, who estimated the motion lasted about 45 seconds.

"It was bumpy and then just shook sideways," said Melida Romo, a waitress at the Border Cafe in Calexico, where three customers also experienced the quake. "We just stood there, holding ourselves."

Calexico police Lt. Jim Neujahr was being interviewed by a local television reporter when the earthquake hit.

"We actually felt dizzy because it went on so long," he said. "Earthquakes happen quite a bit out here, but we get a lot of 3.5 or 3.3 ones and they aren't newsworthy. But (5.7), now that is something."

Scheckel said the quake occurred along the Laguna Salada fault, a 43-mile fault in Baja California. It was a "strike-slip movement" upon the fault, which means the ground slid horizontally, with little if any vertical motion.

Nearly two dozen aftershocks of magnitudes up to 4.1, too mild to be felt in populated areas, were recorded in the first five hours after the main quake.

"We did have a few precursors for this event over the previous few days," said Jennifer Eakins, staff research associate at the University of California San Diego's Scripps Institution of Oceanography.

A magnitude-3.3 earthquake was recorded Monday afternoon, with a 3.1 on Thursday morning. But Scheckel said that kind of activity isn't unusual for the region.

U.S. Geological Survey seismologists said there was a 10 percent chance of a strong and possibly damaging aftershock within the next seven days. The forecast is based on statistics on aftershocks typical for California, and seismologists cautioned that it is only a "rough guide," not based on any special knowledge about the Laguna Salada fault.

Dispatchers for the Imperial County Sheriff's Department in El Centro said they did not get any calls after the earthquake, even though it gave their own building quite a shake.