A magnitude 3.4 earthquake struck near La Habra shortly after 9 a.m. Saturday, the latest in a series of aftershocks to hit the area after a 5.1 temblor the night before displaced a number of residents.
After the 5.1 quake, at least eight homes and 20 apartment units were red-tagged in Fullerton because they are deemed unsafe to occupy, said police Lt. Mike Chlebowski. The damaged residences are located in northern Fullerton, closer to the quake's epicenter, he said.
In La Habra, about 38 people, including seven children, spent the night at a Red Cross shelter.
"We were told many of them were living in a building that was uninhabitable," said Red Cross spokeswoman Meredith Mills.
More than 100 aftershocks have been reported since the 5.1 quake struck, including a shallow magnitude 2.5 earthquake Saturday that was reported at 7:48 a.m. and the 3.4 quake that hit at 9:02 a.m., both near La Habra, according to the U.S. Geological Survey.
Tucked away in cots, the aftershocks went largely unnoticed by evacuees at the shelter in La Habra, volunteers said.
"They slept right through it," said Red Cross volunteer Bonnie Korn. "Of course, we checked to make sure they were all OK."
Among them was Jeff Perea, who said he initially thought "someone had rammed my house with a car" when Friday's night main quake struck.
"After that, it was crazy -- aftershock after aftershock, all night long," he said.
His daughter-in-law, Jessine Luna, 21, said she huddled in a doorway with her daughter in her arms, "even though I've heard that won't protect you."
"There I was with my 3-month-old daughter in my arms. I was praying hard, 'Oh God, please, not right now. We're not ready,'" she said.
Damage from the shaking was scattered across the La Habra area, hitting houses, apartments and businesses as well as street lights that were left dangling precariously.
"From 20 to 30 businesses suffered broken plate glass windows, many of them along Whittier Boulevard," La Habra Police Sgt. David Crivelli said. "There were also some apartments with stucco damage and leaking water."
By 10:30 p.m. Friday, residents had been evacuated from apartment units in the 2500 block of West Whittier Boulevard, the 400 block of North Idaho Street, the 700 block of West 1st Avenue.
An L.A. Fitness center near Imperial Highway and Beach Boulevard had water running off the roof.
The first of a swarm of earthquakes hit the border of La Habra and Brea shortly after 8 p.m. Friday with a 3.6 temblor. At 9:09 p.m., the 5.1 shock hit, followed by at least two more aftershocks in the magnitude-3 range in the next half hour.
The 5.1 quake was relatively shallow, which "means the shaking is very concentrated in a small area," Caltech seismologist Egill Hauksson said Friday night. Hauksson said the quake sequence was unusual in that the 5.1 quake was preceded by the weaker foreshock.
U.S. Geological Survey seismologist Lucy Jones said there was a 5% chance of there being a foreshock of a larger temblor.
"There could be even a larger earthquake in the next few hours or the next few days," Jones said during a media briefing at Caltech soon after the 5.1 temblor.
The quake caused furniture to tumble, pictures to fall off walls and glass to break. Merchandise fell off store shelves, and there were reports of shattered plate glass windows.
Residents across Orange and Los Angeles counties and the Inland Empire also reported swinging chandeliers, fireplaces dislodging from walls and lots of rattled nerves.
The shake caused a rock slide in Carbon Canyon, causing a car to overturn, according to the Brea Police Department. Several people suffered minor injuries in the incident, officials said, and Carbon Canyon Road was closed.
More than 800 homes and businesses close to the epicenter were still without power Saturday morning.
In La Habra Heights, 34 customers were without power, said Susan Cox, a spokeswoman for Southern California Edison. Buena Park had a much wider outage area, affecting 792 homes and businesses.
It was not immediately clear if the outages had to do with downed power lines or if they were related to other structural failures.
"Crews are working to restore service as safely and as quickly as possible,'' Cox said.