Scientists Detect Movement on Major California Fault for First Time

A crack stretches across the road after a 6.4 magnitude earthquake struck the area on July
Mario Tama/Getty Images

A major California fault has begun shifting, and may be capable of producing an 8.0 temblor, according to scientists.

The movement is “a result of this year’s Ridgecrest earthquake sequence destabilizing nearby faults,” according to a study released Thursday by scientists at the California Institute of Technology.

The article stated:

The period of seismic quiescence in Southern California was rudely interrupted by the Ridgecrest earthquake sequence in July 2019. Ross et al. mapped the slip sequences during the magnitude 6.4 and 7.1 earthquakes that shook the region. They found that ruptures of a few larger, but many smaller, faults occurred during both earthquakes. The Ridgecrest sequence calls for rethinking seismic hazard, as multifault ruptures are not usually considered when assessing seismic risk.

In the past, there was no record of movement on the Garlock fault, which lies on the northern edge of the Mojave Desert, producing even a slight earthquake.

“But new satellite radar images now show that the fault has started to move, causing a bulging of land that can be viewed from space,” according to the Los Angeles Times.

Zachary Ross, assistant professor of geophysics at Caltech and lead author of the article, said the research may force scientists to rethink how they define faults and quantify seismic hazards.

“We can’t just assume that the largest faults dominate the seismic hazard if many smaller faults can link up to create these major quakes,” he said.

However, Los Angeles Times reporter, Ron Lin, tweeted Thursday that the chances of a larger earthquake being triggered by movement on the Garlock fault were slim.

Also on Thursday, Gov. Gavin Newsom announced the launch of the nation’s first statewide earthquake early warning system, called the ShakeAlert.

“The ShakeAlert system that has been under development by the U.S. Geological Survey and science institutions for years will now push alerts to cellphones through an app developed by the University of California, Berkeley, and the Wire Emergency Alert system,” according to ABC 7.


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