College Times

Cluster of earthquakes rattles Southern California

By Rebecca Trounson, Los Angeles Times

Published: Thursday, August 9, 2012

Updated: Thursday, August 9, 2012


LOS ANGELES - Some called it an "earthquake cluster," others a "swarm."

Seismologists used the term "earthquake sequence."

Whatever the name, a series of more than 30 small to moderate temblors jolted
Southern California on Tuesday night and Wednesday morning, rattling nerves
but causing no significant damage.

The cluster of earthquakes that struck near Yorba Linda was centered near the
Whittier fault, but preliminary data suggested that fault was not responsible
for the temblor, said Doug Given, a geophysicist with the U.S. Geological

"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 said that of all the quakes, only three were probably felt by
residents. The two 4.5 temblors were felt across a wide swath of Southern
California, with people reporting shaking as far away as Thousand Oaks, the
Santa Clarita Valley, Los Angeles' Westside area and northern San Diego
County, according to the USGS' "Did You Feel It?" website.

"This is all part of the same earthquake sequence; they're all in the same
area," Hutton told reporters.

"It shook us pretty good. We've felt earthquakes before, so it came as no
surprise," said Chris Nordyke, director of marketing at the Richard Nixon
Library and Birthplace in Yorba Linda. "It shook open the door, but nothing
fell off the shelves."

Given said the excitement offers a lesson for the region. "We live in
earthquake country. Earthquakes are normal here, and people should be
prepared," he said.

(Times staff writers Richard Winton and David Zahniser contributed to this


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