5.3 Aftershock Rattles Southland : Temblor: Frightened people flee stores and movie theaters and two fires are started. But there is little other damage from third-largest jolt since the Jan. 17 Northridge quake.

A powerful aftershock to the Northridge earthquake rolled across Southern California on Sunday, starting two fires, briefly disrupting power to thousands of San Fernando Valley residents and sending people fleeing from stores and movie theaters, but causing little damage.

The 5.3 magnitude quake, centered near Panorama City, was felt over a wide area of Los Angeles and Orange counties when it hit at 1:20 p.m. It was the third-strongest of more than 5,000 aftershock to hit the region since the Jan. 17 quake, which killed at least 61 people and caused at least $13 billion in structural damage.

Freeways sustained some cracking in the aftershock, but none were closed, officials said.

Los Angeles city Fire Department officials said two fires were started by the earthquake. A mini-mall blaze in Van Nuys began because of electrical damage caused by the quake, and a transformer at a Department of Water and Power plant near Burbank Airport caught fire after earthquake damage caused oil in the unit to overheat, said Jim Wells, a Fire Department spokesman.

A Sherman Oaks house, moved off its foundation by the Jan. 17 quake and scheduled for demolition today, was sent sliding another 25 feet down the hillside.

The shaker rattled nerves as well, although no injuries were reported.

For fans camped outside the Dorothy Chandler Pavilion for tonight’s Oscar ceremonies, the quake was a second authentic L.A. experience--but it did not move them from their cherished places. Rhea Sprecher, an art teacher from Wisconsin, still managed to spot Debbie Allen, Goldie Hawn and others. “I felt some rumbling under my feet and I said: ‘Would that be an earthquake?’ ”

Inside, where organizers were rehearsing the introduction for the visual effects Oscar, chandeliers swayed, the seats rocked and huge pieces of scenery rattled. “Everybody, stay in your seats!” Oscar director Jeff Margolis ordered over the public address system.

In Malibu, a minor rockslide failed to disrupt traffic. And in Santa Monica, life in the bustling Third Street Promenade shopping and dining area was back to normal shortly after the temblor stopped.

“Seismically, this is a very expected behavior. Probably the big news story in this earthquake is people’s nerves,” said Caltech seismologist Kate Hutton.

Although authorities reported little damage to homes and businesses, hundreds of people were evacuated from malls and theaters in the San Fernando Valley area.

As a precaution, about 1,000 people were removed from IKEA, a home furnishings store in Burbank. Despite shoppers’ anxiety, the evacuation was quick and orderly, said Dennis Rodriguez, the store’s operations manager.

“People were a little frightened. We got workers together with customers and guided them downstairs,” Rodriguez said. Some children were separated from parents but were reunited outside the building, he said.

Another 500 shoppers were evacuated from the Fashion Square Mall in Sherman Oaks, where the aftershock shattered plate glass alongside an escalator and sent some overhead spotlights crashing to the floor. No one was injured at the mall, where the first 34 of the complex’s 140 stores closed since the Jan. 17 quake reopened Saturday, employees said.

“We had the rain yesterday and another aftershock today,” said Bob Smith, a mall employee. “It’s been a tough weekend.”

At Valley movie theaters, patrons fled their seats as they were showered with broken plaster and other debris.

James Booth of Burbank was on a bucket lift filling cracks on the second floor of the Cal State Northridge science building when the shaking hit.

“I thought it was this jackass shaking the bottom of the lift,” Booth said, pointing to a co-worker. “I thought the entire building was going to come down.”

In the Mid-City area, Percy Bennett’s furniture and appliance store still had plywood up from the Jan. 17 quake, which shattered its glass front. Inside, another souvenir of Jan. 17 is the ceiling that still has a hole the size of a big screen TV.

On Sunday, Bennett just pulled his merchandise out onto the sidewalk and kept working.

“This quake was nothing compared to that big one,” he said. “I was sitting here on this (exercise bike) just peddling along when I started swaying. But yeah, I sure could feel it.”

A Santa Monica conference of the Anxiety Disorders Assn. of America ended with a bang as the quake struck. “I tell you, the timing couldn’t have been better. It was the last day, the last minute, the last second and it hit. It was pretty ironic,” said association President Jerilyn Ross.

At Disneyland in Anaheim, some of the more elaborate attractions were temporarily closed down. At Universal Studios in Universal City, all attractions closed immediately after the quake.

Chris Cangco of Glendale was on a tram going over a bridge that falls apart as part of the special effects tour when the quake hit.

“I didn’t realize it was an earthquake at the time. I thought it was an effect of the . . . tram.”

The ride continued, and only when the 45-minute trip ended did someone inform the riders that a real earthquake had hit.

The aftershock knocked out power to about 77,000 San Fernando Valley residents, most for five minutes or less, DWP spokeswoman Mindy Berman said. However, about 7,000 customers in Van Nuys were without electricity for half an hour.

Caltrans reported minor damage to freeways near the epicenter of the aftershock but none serious enough to close any roads.

On the Golden State Freeway north of Granada Hills, the aftershock dislodged temporary asphalt filler that had been used to close a 6-to-8-inch gap caused by the Northridge quake. Temporary asphalt fixes also came loose in a concrete overpass at the interchange of the Simi Valley and San Diego freeways. Caltrans crews quickly refilled the gaps without shutting down any freeways.

“It’s not something that would alarm anyone,” said Caltrans spokeswoman Margie Tiritilli. “It’s super-minor.”

Caltech seismologists said the aftershock was expected, and in the normal range.

“This is perfectly normal. This is what we expect,” said Egill Hauksson, a seismologist at Caltech. He said Sunday’s shaking occurred on the east side of the fault plane where the main shock occurred on Jan. 17, but was not on the same fault.

The aftershock was centered about two miles west-northwest of Panorama City, and about three miles northeast of the epicenter of the Northridge quake, said Hutton, within a “pie-shaped aftershock zone” where shocks have been clustered.

The aftershock was closer to the surface than the Northridge quake, with preliminary estimates putting it about nine miles below the earth’s surface, compared to 12 miles for the main Jan. 17 temblor.

With a preliminary magnitude of 5.3, the quake is 1/20 the magnitude of the main Jan. 17 quake. Hutton said the number of aftershocks continues to decline each month.

Sunday’s temblor “is an aftershock, but it is also an earthquake on its own” and will produce its own aftershocks, she said. However, there is only a 1 in 20 chance that it was a foreshock to a larger quake.

A 3.4 magnitude aftershock was recorded at 3:34 p.m. Sunday, and another reading 2.7 hit at 8:05 p.m., seismologists said.

Meanwhile, a spokesman for Farmers Insurance Co. said Sunday’s major aftershock could temporarily suspend earthquake insurance underwriting in the region.

“Geologists may call this an aftershock, but this is a separate quake for insurance purposes,” Jeffrey Beyer said.

State law allows insurers to impose a moratorium of up to 60 days on sales of earthquake insurance after a quake occurs. A moratorium after the Jan. 17 Northridge quake covered about 100 square miles and lasted no more than 30 days at many companies.

“I don’t know of any moratoriums still in effect,” Bill Schulz, spokesman for the state Department of Insurance, said.

The aftershock prompted some business owners and authorities to close some public structures so they could check for structural damage.

In Burbank, owners shut down the 75-store Media City Center mall for the day after sprinklers jolted by the aftershock drenched some shoppers. City building inspectors also ordered the mall parking structure closed until it could be inspected, said Lt. Don Brown of the Burbank Police Department.

At the Glendale Galleria, “we heard the building just rumble,” said Drew Boghorsyan of the mall’s customer services department. Merchants at 26 of the mall’s 248 stores closed up shop to go home, but Boghorsyan knew of no damage.

A spokesman for the Los Angeles Unified School District said schools will be open as usual today, although workers will inspect repairs from the January quake to make sure they held. In all, 76 public schools were damaged in January.

Doug Brown, the district’s facilities director, said: “We will be out at the schools where there was previous damage to make sure the repairs are still holding.

“We’re going to hit the ones that had the most damage and the least permanent repair work done and work our way back from there.”

The Washington, D.C.-based Anxiety Disorders Assn. had been discussing such problems as quake-related stress in its four-day conference at the Loews Santa Monica Beach Hotel.

As the final seminar drew to a close Sunday, the fifth-floor banquet room began to shake and the chandeliers rattled noisily. The seminar ended with applause and laughter--for the quake.

On Friday, the conference had featured a seminar called “The Los Angeles Earthquake and Post-Traumatic Stress Disorder.” And some of the psychiatrists and social workers later kidded one another about earthquakes. “Jokingly, we who’d never experienced an earthquake said: ‘Gee, I wish I could feel just a little one so I could know what it feels like,’ ” Ross said.

Also contributing to this report were Times staff writers Jill Bettner, Leslie Berger, Leonard M. Bernstein, Miguel Bustillo, Jack Cheevers, Aaron Curtiss, Sam Enriquez, Ralph Frammolino, Laura Galloway, Denise C. Gellene, Hugo Martin, Susan Moffat, Ann W. O’Neill, Bob Pool, Lisa Richardson, Julie Tamaki, Teresa Ann Willis and correspondent Kathleen Kelleher.