4.7 Earthquake Was Aftershock

A moderate earthquake that rattled North County and parts of San Diego early Wednesday was actually an aftershock of a larger quake that hit the area four years ago, scientists said.

There were no reports of injuries or damage caused by the earthquake, which struck at 1:54 a.m. and was of 4.7 magnitude. It was centered in the Pacific 28 miles southwest of Oceanside.

A spokesman for the California Institute of Technology Seismology Laboratory in Pasadena said the temblor was an aftershock of the 5.3-magnitude quake that hit the area July 13, 1986.

Oceanside police officer Rudy Martinez said the department received “no calls, no damages . . . no nothing.”

Kimberly Mathis, a senior dispatcher for the San Diego County Sheriff’s Department, said dispatchers working overnight received about “20 to 25 calls (from) people asking if there was a quake.” A dispatcher for the Carlsbad Police Department said only one person called to ask about the quake. Bill Robinson, a spokesman for the San Diego Police Department, said the department received a handful of calls.

One Oceanside man was falling asleep on his water bed when the quake hit.

“I heard a little bit of rattling on the dresser and in the bathroom cabinet . . . and then it felt like I was on a wave,” Ben Sialega said. “I stayed in bed waiting for the next wave. I thought it was going to be a big one.”

Sue Hendershott, a circulation clerk for the Carlsbad Public Library, said the quake woke her from a deep sleep. It felt “like a large jolt and sounded like a big crack,” she said.

An earthquake centered in the same region hit on July 13, 1986, at 6:46 a.m. and caused an estimated $500,000 in damage. One person died of a heart attack, and 29 others were injured in the quake, said Bill Brazier, a senior clerk for the county Office of Disaster Preparedness. The office had received no reports of damages from Wednesday’s temblor, he said.

The 5.3 quake in 1986 was the largest to hit the county or its offshore areas since scientists began monitoring seismic events here in 1932.

The 1986 quake was followed about two weeks later by several strong aftershocks. Since then, several thousand aftershocks have occurred in the same region, said Robert Finn, a Caltech spokesman.

An aftershock is an earthquake that occurs in the same region.