Researchers Are 99.9% Sure of Major L.A. Earthquake Within Three Years

Thursday, October 22, 2015

A new study (pdf), led by NASA’s Jet Propulsion Laboratory at California Institute of Technology (Caltech), predicts with 99.9% certainty that a major earthquake will hit Los Angeles within three years

The researchers drew their conclusion after studying the 5.1 quake in nearby La Habra on March 28, 2014. They predict an L.A. shaker of between magnitude 5 and 6.3.

Using airborne radar data, the scientists measured surface deformations in the Earth’s crust after the La Habra quake and concluded they “likely reflect strain accumulated on deeper faults, which remain locked and may be capable of producing future earthquakes.”

That pent up energy is going to be released soon, the study said, based on 81 years of data on magnitude 5 earthquakes in the region. There have been 32, or about one every three years.

Lead researcher geophysicist Andrea Donnellan did not predict what fault or faults the quake might occur on. “Identifying specific fault structures most likely to be responsible for future earthquakes for this system of many active faults is often very difficult,” she said.    

Thomas Heaton, professor of engineering seismology and director of the Earthquake Engineering Research Laboratory at Caltech, was even more dismissive. He told the Pasadena Star-News, “As far as I’m concerned, there has never been a successful earthquake prediction and a scientific breakthrough would be required for us to make a scientifically based prediction.”

After reading the research paper, Heaton said it “does not meet my definition of science. That is, this type of slip deficit has been tried in the past, but it has been shown to have minimal predictive power.”

The U.S. Geological Survey (USGS), said on its Facebook page that the study did not provide “a clear description of how these numbers were derived” and lacked review by either the California Earthquake Prediction Evaluation Council or the National Earthquake Prediction Evaluation Council.

Lucy Jones, the “Earthquake Lady” at USGS, talked to KPCC and didn’t sound like she was buying the story. USGS does its own quake risk analysis and Jones said, “It's nowhere near a 99.9 percent number.”

She would put the three-year risk at 85%.  

–Ken Broder


To Learn More:

Big Earthquake Chances High for Los Angeles County Fault, JPL Scientist’s Study Says (by Larry Wilson, Pasadena Star-News)

Controversial Study Claims 99.9 Percent Chance of Major Los Angeles Earthquake in 3 Years (by Sanden Totten, KPCC)

NASA Study Improves Understanding of LA Quake Risks (Jet Propulsion Laboratory)

Potential for a Large Earthquake near Los Angeles Inferred from the 2014 La Habra Earthquake (by Andrea Donnellan, Lisa Grant Ludwig, Jay W. Parker, John B. Rundle, Jun Wang, Marlon Pierce, Geoffrey Blewitt and Scott Hensley, Earth and Space Sciences) (pdf)

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