4.3 Earthquake Rattles Four-County Area

A magnitude 4.3 earthquake struck Monday morning about five miles north of Yorba Linda, rattling the Carbon Canyon area, causing light damage and prompting the evacuation of a few classrooms near the epicenter.

The 10:14 a.m. temblor near the Whittier fault was centered five miles southwest of Chino in San Bernardino County at a depth of five miles. It was felt moderately in Orange, Los Angeles and Riverside counties.

While some Orange County residents watched their walls and furniture shudder for a few moments, authorities said there were no emergency calls directly related to the quake. A smoking transformer at Edison High School in Huntington Beach darkened classrooms and forced closure of the school Monday and today. Although the equipment failed within minutes of the temblor, it wasn’t clear if they were related, Assistant Supt. Patricia Koch said.

At Chino Hills’ Glenmeade Elementary School, administrators sounded the fire alarm and evacuated 825 students to two playgrounds for half an hour. Principal Pat Miller said she heard a boom, and teachers ordered students to duck under their desks.

But no damage was found.

At a Lucky supermarket in Chino Hills, manager Ron Viggiano said a jar of pickles and a bottle of barbecue sauce were the only items knocked off shelves. Similarly, a few homeowners reported household goods falling.

At the Orinda Market near Brea eff Itani was tending the convenience store when he heard a booming noise. “I thought the roof fell,” Itani said, but nothing fell and nothing was damaged.

Two doors from the store, engineers Septimiu Apahidean and Stuart Yamamoto were testing computer prototypes at CKC Laboratories when they heard a sound Apahidean described as “like a sonic boom.”

“I thought a truck hit the side of our building,” he said. “We ran outside and didn’t see a traffic accident, so we turned on the radio and heard it was an earthquake.”

At the Western Hills Country Club in Chino Hills, assistant pro Joe Dedios remarked, “It was the kind of earthquake where somebody might have gotten lucky, if their ball was next to the hole”--because ground motion might have knocked it in.

Car alarms were set off near the epicenter, and there was a brief alarm but no damage at the 6,400-inmate California Institution for Men in nearby Chino.

As with any highly noticeable quake in a California metropolitan area, thousands of people clogged phone lines and the Internet seeking quick information. For several minutes, many callers near the epicenter could not get a dial tone on their phones and Internet users could not get a response on quake Web sites.

At Caltech, seismologist Egill Hauksson said the Whittier fault, which branches off the lengthy Elsinore fault and runs about 25 miles from Corona to Whittier, was “most consistent” with causing the quake.

The Whittier fault is a surface fault not involved in the 1987 Whittier Narrows earthquake, which was on a buried thrust fault, Hauksson said.

But, he said, the Whittier fault was involved in a few big earthquakes in prehistoric times and has perhaps three times the annual average slip of the better-known Newport-Inglewood fault. He said it is believed capable of triggering a quake as strong as 7.2.

Elsewhere in California, the swarm of volcanic earthquakes near the Eastern Sierra town of Mammoth Lakes continued with a magnitude 4.1 jolt recorded at 6:11 a.m.

The quake, at a depth of four miles, was centered near the Mammoth airport six miles southeast of town, and was one of more than 180 quakes recorded near Mammoth on Monday. No damage was reported.

Times staff writer Tom Gorman contributed to this report.