10 Percent Chance of Another Big Earthquake in Southern California After Latest Temblor: Expert

July 6, 2019 Updated: July 6, 2019

There’s a 10 percent chance that another strong earthquake will strike southern California, an expert said after a 7.1 magnitude quake struck late July 5.

That quake was preceded by a 6.4 magnitude quake, which hit on July 4 and was the largest temblor in the region in around two decades.

Both quakes, along with hundreds of aftershocks, were located in a remote part of the state: Searles Valley in the Mojave Desert.

Dr. Lucy Jones, a seismologist at Caltech, said that there was “about a 1 in 10 chance that Searles Valley will see another” magnitude 7 quake.

“That is a 9 in 10 chance that tonight’s M7.1 was the largest,” she wrote on Twitter after the latest quake.

The estimate came several hours after Jones said that the 7.1 quake “has a 1 in 30 chance of being followed by something even bigger.”

“Smaller quakes—M5s are likely and a M6 is quite possible,” she said.

“So the M6.4 was a foreshock. This was a M7.1 on the same fault as has been producing the Searles Valley sequence. This is part of the same sequence,” she also wrote. “This is the same sequence. You know we say we 1 in 20 chance that an earthquake will be followed by something bigger? This is that 1 in 20 time.”

Jones told reporters at a press conference that there was a slightly greater than 50-50 chance that the Owens Valley will see another quake of magnitude 6 or higher, reported the Los Angeles Times.

She also noted a magnitude 7 earthquake “usually has aftershocks that last for years.”

Food that fell from the shelves litters the floor of an aisle at a Walmart following an earthquake in Yucca Yalley, Calif., on July 5, 2019. (Chad Mayes via AP)

Robert Graves, a seismologist with the U.S. Geological Survey in Pasadena, said that the 7.1 quake was around eight times stronger than the 6.4 quake the day prior.

That quake was a reminder that California was “way overdue” for a huge earthquake, physicist Michio Kaku said.

“We’re playing Russian roulette with Mother Nature. You realize the last big earthquake to hit the L.A. segment of the San Andreas fault was 1680. That’s over 300 years ago. But the cycle time for breaks and earthquakes on the San Andreas fault is 130 years, so we are way overdue. In any given year, the probability of the big one is 3 percent in any given year. Think about that,” he told CBS.

Kaku said predicting earthquakes isn’t easy but statistics can give people an idea of when large ones will happen.

California Earthquake
Volunteers assist with cleanup following a 6.4 magnitude earthquake at the Ridgecrest, Calif., branch of the Kern County Library on July 5, 2019. (Jessica Weston/Daily Independent via AP)

“Look, I’ll be blunt. It’s voodoo black magic trying to predict when an earthquake is going to take place. The Japanese are the world’s leader in this area, and they can only predict an earthquake perhaps maybe a few seconds to a minute before it actually hits. So we are children when it comes to understanding earthquake prediction,” he said.

“In 30 years’ time the probability of the big one is about 100 percent. So we will see the big one. It’s inevitable. It’s going to happen. It’s the law of physics.”

Paul Caruso, a geophysicist with the United States Geological Survey in Golden, Colo., told The New York Times that the forecast hasn’t changed for the San Andreas fault.

“We are not changing our forecast for the San Andreas,” Caruso said. “We still believe there’s a 70 percent chance of a magnitude 7 or greater in southern California before 2030.”

Follow Zachary on Twitter: @zackstieber
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