Magnitude 4.6 temblor rattles plates and nerves

Thursday’s earthquake did little more than topple a few household items and startle people in the Los Angeles area from their slumber.

After five years of relative quiet, it was a reminder of life in earthquake country.

The magnitude 4.6 temblor was the first quake with a magnitude of 4.0 or greater in Los Angeles County in about five years, according to Caltech seismologist Nick Scheckel.

“It’s been pretty quiet,” Scheckel said.

The temblor struck just before 1 a.m. and was centered roughly four miles northwest of Chatsworth, according to a preliminary report by the U.S. Geological Survey.

Although the quake was classified as light with moderate effects by seismologists, a bridge about 12 miles north of Chatsworth was closed until midday. There were no reports of injuries.

In an area traumatized 13 years ago by the Northridge quake, Thursday’s temblor was greeted by many with jaded disregard, but others were jolted into action. The Northridge quake in 1994, which had a magnitude of 6.7, struck early Jan. 17, killed 61 people and caused more than $40 billion in damage.

Since the Northridge temblor, there have been 69 magnitude 4.0 or greater earthquakes in the Los Angeles County area, Scheckel said. However, 62 of them are considered aftershocks. Thursday’s was not.

“It’s the way the Earth behaves,” Scheckel said. “There are periods when there’s a flurry of activity, and there are times of quiescence. It looks like we’re in that range right now. The question is, when does that change? And we don’t know.”

Anteneh Alemu, 13, of Chatsworth was checking his e-mail when he felt a jerk.

“In the kitchen, everything was shaking,” he said. He quickly threw himself under a table while his mother screamed, “Come here, come here!”

The temblor, like the Northridge quake, was a thrust earthquake -- which occurs when two fault blocks push into each other and one slips over the other -- but it was not strong enough to rupture the Earth’s surface, Scheckel said.

Its epicenter -- in the Santa Susana Mountains near the Santa Susana fault -- was roughly 7.6 miles from the Northridge quake epicenter, Scheckel said. The tremors were felt for a “couple to a few seconds” in a radius of more than 60 miles from Santa Barbara to Palmdale and Gorman to Irvine, Scheckel said.

“It’s like dropping a pebble into a pond, so as the ripples ring out it tends to last longer and longer the farther it goes, energy-wise,” Scheckel said.

Desiree Kane, 44, was trying to sleep in her Simi Valley home when she heard picture frames fall and then the sound of breaking glass. The quake broke an antique picture in her bathroom, given to her by her grandmother, she said.

She ran to get her twin 14-year-old girls, then huddled with them by the front door.

“It was quite scary,” Kane said. She and her girls placed their shoes by their front door for a quick getaway if needed. Kane called her mother in West Hills, but she had barely felt a thing.

Kane said they will probably double-check on their earthquake gear in the garage.

Angelenos last felt a major earthquake in October 1999: the magnitude 7.1 Hector Mine temblor in the Mojave Desert, which was more widespread and rolled stronger and longer than Thursday’s quake, Scheckel said.

Thursday’s quake left no significant damage, said Ron Myers, a spokesman for the Los Angeles Fire Department.

Authorities found minor cracking and small chunks of fallen concrete at the Whites Canyon Bridge in Santa Clarita, about 10 miles from Chatsworth, and closed it for several hours.

City and county engineers determined that the cracks were “cosmetic,” Sheriff’s Lt. Diane Walker said.

For many residents of Chatsworth, the quake was minor compared with their memories of “the big one” in Northridge a few miles away.

Ashton Kirschbaum, 73, has lived in Chatsworth for 30 years and said this quake was “infinitesimal” in comparison.

“It’s like me sneezing; it’s not even a big deal. It’s a tremor,” he said. The Northridge quake destroyed a 160-foot-long wall around his home, and parts of the house. Thursday’s quake scared one of his three Persian cats under a bed for a few seconds, but it was a quick jolt.

“If someone fell asleep, took a pill and got up, they wouldn’t even know there was an earthquake,” Kirschbaum said. “When you walked outside after the Northridge, you could tell.”

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tami.abdollah@latimes.com