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Earthquake swarm puts California town on edge

Posted: August 27, 2012 2:30 p.m.
Updated: August 27, 2012 2:30 p.m.
 

BRAWLEY, Calif. (AP) — A series of small to moderate earthquakes that shattered windows and knocked trailer homes off their foundations is putting people in this small farming town 100 miles east of San Diego on edge as they continue to feel jolts that scientists said could last for days.

Hundreds of quakes shook Imperial County Sunday and were felt in surrounding counties. Most were minor, but two registered at magnitude-5.5 and magnitude-5.3.

No injuries were reported in the region, which has a long history of such earthquake swarms.

"The type of activity that we're seeing could possibly continue for several hours or even days," said U.S. Geological Survey geophysicist Robert Graves.

The seismic activity is not unusual, but scientists have puzzled over the cause. The last significant swarm occurred in 2005 when a thousand quakes, the largest at magnitude-5.1, shook the south shore of the Salton Sea. In 1981, a cluster of quakes hit a region five miles to the northwest of Sunday's sequence, with the largest measuring a magnitude-5.8. The region was very active in the 1960s and 1970s.

"They seem to light up and turn off for reasons we don't understand," said USGS seismologist Susan Hough.

Despite the shaking, the swarms have not triggered any significant quake in the past, Hough said.

The quakes pushed 20 mobile homes at a trailer park off their foundations and rendered them uninhabitable, said Maria Peinado, a spokeswoman for the Imperial County Emergency Operations Center. A red-tile roof apparently collapsed and landed on a wooden fence.

Sporadic power outages, at one point affecting 2,500 Imperial Irrigation District customers, also prompted authorities to evacuate 49 patients from one of the county's two hospitals, Peinado said. Police also received numerous calls about gas leaks and water line breaks.

"It's not uncommon for us to have earthquakes out here, but at this frequency and at this magnitude it's fairly unusual," said George Nava, the mayor of Brawley, a town of 25,000.

"And the fact that the aftershocks keep coming are a little alarming," he said.

@2012 The Associated Press

 

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