A magnitude 4.0 earthquake jolted Orange County on Monday afternoon, but there were no reports of damage or injuries, seismologists said.
The 4:20 p.m. quake was centered 8 miles east-southeast of Yorba Linda, just south of the Riverside Freeway on the Orange County side of the Riverside-Orange county line. It occurred at a depth of 6 miles, scientists said.
Shake maps issued by the California Institute of Technology in Pasadena and the U.S. Geological Survey showed the strongest shaking extended from the epicenter south to Irvine and Tustin. But the quake could be felt as far north as Los Angeles and as far south as Temecula and Oceanside.
A 1.8 aftershock in the same location at 5:45 p.m. was not strong enough to be felt.
Robert Tindol, a Caltech spokesman, said the day's two seismic events were not aftershocks of any Southern California quake.
Amber Roth said she was at home in Yorba Linda when the quake struck. "It felt like a quick jolt," she said, "almost like a big truck driving by. It just sort of shook the windows and made rattling noises. It scared me. Nothing happened though. I came outside, my neighbor came outside--then everybody just went back to their business."
Orange County Fire Authority Capt. Paul Hunter said Monday afternoon his agency was making checks, even though no damage was evident.
"We have a helicopter in the air over the epicenter just to make sure we're not missing anything," he said.
Marleen Madge, who works at a Tustin real estate office, said the quake "started like a little rumble and then a big jolt."
"It shook the windows. That kind of made me a little leery," she said.