Latest Southern California earthquakes hit in 'known active area'
August 8, 2012 | 3:45
The cluster of earthquakes that struck near Yorba Linda in the last 24 hours was centered near the Whittier fault, a major fault, but preliminary data suggested it was not responsible, said Doug Given, a geophysicist with the U.S. Geological Survey.
“There are lots and lots of little faults all over that area,” Given said of the northern Orange County region where the quakes were centered. “It’s a known active area.”
The shaking began with a magnitude 4.5 earthquake near Yorba Linda about 11:30 p.m. Tuesday, bookended by another 4.5 quake about 9:30 a.m. Wednesday, but with many smaller ones in between.
At a news conference Wednesday morning, Kate Hutton of the U.S. Geological Survey at Caltech said there had been at least 30 quakes since Tuesday night, but only three could be felt by residents. She said officials are studying the quakes to understand whether it was a swarm or some other type of pattern.
"This is all part of the same earthquake sequence; they're all in the same area,'' Hutton told reporters at the briefing. "We haven't had anything in the L.A. Basin in the last few years, but that doesn't mean we're totally quiet, and we certainly have been active in the southern part of the state."
The quakes jolted residents but caused no major damage.
Given said the temblors serve as a useful reminder to residents. “We live in earthquake country. Earthquakes are normal here and people should be prepared,” he said.