Friday, 31 August 2012

Earthquake swarm in California

Southern California town declares emergency over quake swarm
The southern California town of Brawley has taken the unusual step of declaring a state of emergency after a swarm of earthquakes rattled nearly 20 mobile homes off their blocks and forced a slaughterhouse to close, the mayor said on Wednesday.
 

30 August, 2012

It is uncommon for quake-hardy California cities to declare emergencies due to tremors, but Brawley mayor George Nava said the earthquake swarm is a unique case because it has lasted for days and caused millions of dollars in damage.

The cluster of relatively small quakes, which are caused by water and other fluids moving around in the Earth's crust, began on Saturday evening and climaxed the next day with a 5.5 temblor, according to the U.S. Geological Survey.

The tremors were continuing on Wednesday and geologists say there have been hundreds in total.

Nava said leaders in Brawley, a city of 25,000 residents south of the state's inland Salton Sea and 170 miles (275 km) southeast of Los Angeles, declared a local emergency late on Tuesday. Officials with surrounding Imperial County made a similar declaration on Wednesday.

Nineteen mobile homes were knocked off their blocks and their residents forced out, Nava said. The auditorium at Brawley Union High School has been damaged and closed off, and the National Beef slaughter plant in Brawley has been temporarily shut down due to damage, he said.

Local businesses have suffered millions of dollars in losses from closures and from customers staying away, Nava said. But he could not give an exact account of quake-related losses.

The Red Cross and local government agencies will offer services to residents on Friday and Saturday at a local center. The emergency declaration allows Brawley to receive more assistance from Imperial County, Nava said.

At one point, about 10,000 residents in the city were without power, and the quakes have also caused water line disruptions, Nava said.

"When you don't have an AC or running water, it's just not a good thing in this weather," he said.

Jeanne Hardebeck, research seismologist for the U.S. Geological Survey, said earlier this week that the cluster of quakes is not a sign that a larger temblor is imminent


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Yorba Linda earthquake a likely aftershock from earlier cluster
The 4.1 earthquake that jolted Yorba Linda on Wednesday afternoon appears to be an aftershock of the cluster of quakes that hit the region earlier this month, seismologists said

29 August, 2012

The jolted area included southeastern Los Angeles County, Orange County and the Inland Empire. The quake occurred in about the same location of an earthquake doublet, two 4.5 quakes that occurred on Aug. 7 at 11:23 p.m. and Aug. 8 at 9:33 a.m. The area was also hit by a 4.0 quake on June 14.

Wednesday's quake, which hit at 1:31 p.m., was located near the center point of the magnitude-5.5 Chino Hills earthquake that reverberated through the Los Angeles Basin in the summer of 2008, U.S. Geological Survey seismologist Lucy Jones told The Times.

Wednesday's quake appeared to be located in the "Yorba Linda trend," a seismic area identified by Caltech geophysicist Egill Hauksson in 1990, that might be a buried fault.

Many who felt the quake said it was relatively mild.

At Vinjon's Kennel in Yorba Linda, the quake hit just as Carisa Feeney, 22, was giving a bath to a year-and-a-half-old boxer mix. When the quake delivered its single strong jolt, the dog leaped up in the tub –- and both quickly ran outside.

"I'm pretty much covered in water," Feeney said.

Nancy Ferguson, who owns SGO Designer Glass in Old Town Yorba Linda, said, "We had a big jolt, just for a few seconds, then everything just kind of swayed."

Ferguson, who has hundreds of pieces of glass on display in her store, said she holds her breath every time there's an earthquake. "But nothing fell over today, so we're feeling pretty lucky," she said.

It is unlikely that the earthquake swarm that has hit Imperial County with hundreds of quakes since the weekend is related to Wednesday's quake in Yorba Linda, Jones said.


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