Mojave Desert Town Rocked by Big Followup Quake, This One Magnitude 7.1

Updated 11:18 a.m., Saturday, July 6: 

Just 32 hours after a 6.4 magnitude earthquake shook the town of Ridgecrest and a wide area across Southern California, a second, stronger quake struck the region.

The U.S. Geological Survey said the magnitude 7.1 quake struck at 8:19 p.m. about 10 miles outside Ridgecrest, a town of 29,000 that was shaken by a 6.4 earthquake on Thursday morning. The epicenter is about 125 miles northeast of Los Angeles.

Seismologists at Caltech in Pasadena estimated Friday night's quake was 10 times more powerful than the Fourth of July event, now considered a foreshock.

They said the fault causing the earthquakes appears to be growing, now likely to be 25 to 30 miles long, according to Los Angeles Times. More quakes are expected.

Gov. Gavin Newsom declared a state of emergency for Kern County and San Bernardino County to expedite state assistance for the quake zone.

Newsom also requested a Presidential Emergency Declaration for official federal assistance. The Federal Emergency Management Agency has been providing resources to local agencies.

As of Saturday morning, no fatalities or major injuries have been reported, according to a press conference held by the Governor's Office of Emergency Services (OES). Officials also announced that local commodity distribution stores reopened to the public, the power was set back on for most of the affected areas and all repairs to damaged roads have been made.

Aftershocks occurring over a 50 kilometers wide area continued Saturday morning.

Kern County Fire Chief David Witt confirmed Friday night that his department and other agencies were responding to numerous medical aid calls.

The Kern County Fire Department's online incident report system showed crews responding to several structure fires, including one at a movie theater, and a spate of reports of broken gas lines and downed power lines.

Chief Witt said mutual aid had been requested from Fresno and Orange counties.

Mark Ghillarducci, director of the OES, said in a Friday evening briefing the agency had received "significant reports of structure fires, mostly as a result of gas leaks or gas line breaks throughout" Ridgecrest.

He also said there was a report of a building collapse in Trona, a town of 1,900 northeast of Ridgecrest and 12 miles from the epicenter of Friday night's quake. He said the full extent of damage wouldn't be known until after daylight Saturday.

The Los Angeles Times reported widespread damage in Trona, with numerous homes damaged, gas lines broken and the San Bernardino County Sheriff evacuating residents.

Online, people reported impacts from the quake around Southern California, in the Central Valley and as far away as Las Vegas.

In Ridgecrest, the violence of the ground motion was demonstrated in a video showing water sloshing in a swimming pool.

Television images of Dodger Stadium showed significant shaking during the fourth inning of the game between the Los Angeles Dodgers and the San Diego Padres.

Friday night's quake sequence began with a 5.0 shock at 8:16 p.m., followed by the 7.1 quake just 3 minutes later.

Geophysicists had cautioned that after Thursday's earthquake numerous aftershocks could be expected in the seismically active area and that there was a high probability of strong aftershocks -- and perhaps a follow-up quake that would be stronger than the initial 6.4 shake.

They repeated that warning after Friday night's earthquake.

"Like any quake, today's M7.1 has a 1 in 20 of being followed by something even bigger," Caltech seismologist Lucy Jones said on Twitter Friday night. She said magnitude 5 quakes are likely in the coming days and a magnitude 6 is "quite possible."

"You know we say (there's a) one in 20 chance that an earthquake will be followed by something bigger?" Jones wrote. "This is that 1 in 20 time." She added that that same one in 20 chance continues for a quake bigger than Friday's 7.1 shock.

Original post:

A 6.4 magnitude earthquake in a remote desert area northeast of Los Angeles shook a large swath of Southern California on Thursday morning and caused fires and other damage in a town of 29,000 near the epicenter.

The U.S. Geological Survey said the temblor struck at 10:33 a.m. PDT and was centered about 10 miles from the Kern County town of Ridgecrest, about 125 miles northeast of Los Angeles.

The Kern County Fire Department said it responded to dozens of incidents in and around Ridgecrest, including several structure fires.

A widely felt magnitude 5.4 quake at 4:07 a.m. Friday was the strongest aftershock thus far. Seismologists had said there was an 80% probability of an aftershock of that strength within a week.

Kern County officials reported that the 15 or so patients at Ridgecrest Regional Hospital were evacuated because of damage there.

Ridgecrest Mayor Peggy Breeden told CNN that utility workers were assessing broken gas lines and turning off gas where necessary.

Power lines were reported down in the area around the epicenter, and Southern California Edison reported about 7,500 customers without power in Ridgecrest and surrounding communities.

The quake was felt over a wide area, with reports of shaking coming from Los Angeles, Bakersfield and Las Vegas.

"It almost gave me a heart attack," said Cora Burke, a waitress at Midway Cafe in Ridgecrest, of the big jolt. "It's just a rolling feeling inside the building, inside the cafe and all of a sudden everything started falling off the shelf, glasses, the refrigerator and everything in the small refrigerator fell over."

Video posted online of a liquor store in Ridgecrest showed the aisles filled with broken wine and liquor bottles, knocked-down boxes and other groceries strewn on the floor. Flames were seen shooting out of one home in the community.

KQED producer Don Clyde, visiting in the town of Laughlin, Nevada, about 50 miles south of Las Vegas and 170 miles east of the epicenter, described the shake as a "slow, rolling earthquake that seemed to last at least 10 to 15 seconds."

"My mom has lived here about 14 years and can’t recall feeling one in the area," Clyde said.

The earthquake was the strongest in Southern California since the 7.1 magnitude Hector Mine earthquake which hit the Twentynine Palms Marine Base in 1999.

Thursday's quake was followed by more than 80 aftershocks in the first 2½ hours after the initial 6.4 temblor. Those included a pair of 4.6 shakes. Scientists said Thursday that more powerful aftershocks are still possible.

Caltech seismologist Lucy Jones said, in an afternoon media briefing in Pasadena, that there's an 80% chance of a magnitude 5 earthquake and a 20% chance of a magnitude 6 temblor in the area in the next week -- with the probability dropping after Thursday.

A USGS aftershock forecast said the area could experience hundreds of temblors of magnitude 3 or higher in the next week, with a 9% chance of an earthquake more powerful than the 6.4 main shock.

Caltech seismologists said the quake appeared to involve two separate faults northeast of Ridgecrest.

Asked to characterize the seismic character of the area, Jones said, "Lots of faults, lots of activity."

"This was not unexpected in this area," said Robert Graves, another Caltech scientist. "Having a 6.4 is totally typical."

Asked whether Thursday's quake made a damaging quake on the San Andreas Fault near Los Angeles less likely, Jones answered, "That's wishful thinking."

Glenn Pomeroy, CEO of the California Earthquake Authority, said the quake was "an important reminder that all of California is earthquake country," and showed why people in the state must be prepared for such events.

Pomeroy said: "It's important to know what to do to stay safe when the ground starts shaking — drop, cover and hold on — and to take other steps to prepare to survive and recover from damaging earthquakes, such as to retrofit homes built prior to 1980 and the advent of modern building codes, which may be more vulnerable to earthquake damage, and consider earthquake insurance to protect ourselves financially."

Pomeroy urged the estimated 2,000 people in the region hit by the quake who have California Earthquake Authority insurance policies to contact their residential insurance agencies as soon as possible. Information on how to file a policy claim is on the agency's website: EarthquakeAuthority.com, he said.

This post contains reporting from The Associated Press.