Ridgecrest Earthquakes May Have Caused ‘Slight’ Increase in Chance of Quake on San Andreas Fault: Experts

Responding to a recently published study pointing toward increased earthquake risk on the San Andreas fault due to last year’s powerful earthquakes in Ridgecrest, Pasadena’s longtime resident seismological sage said the research is interesting, but unproven, and indicated only a slight potential for increased risk.

The study, published Monday in the Bulletin of the Seismological Society of America, indicated that the powerful shaking in Ridgrecrest in July of last year could increase the chance of a 7.5-magnitude or greater temblor on the Garlock fault to 2.3%, or 100 times more likely than previously estimated at .023%, the Los Angeles Times reported.

Study authors determined an earthquake on the Garlock fault could, in turn, increase the likelihood of a large earthquake on the San Andreas fault to1.15%, which is 3 times higher than previous estimate of .35%, according to the Times.

The damaging 7.1 magnitude Ridgecrest earthquake on July 5, 2019, was preceded by a 6.4-magnitude foreshock on July 4, 2019, as well as aftershocks as strong as magnitude 5.4 in the hours after the main earthquake.

Renowned seismologist Lucy Jones, who headed the U.S. Geological Survey’s operations at Caltech for years before entering semi-retirement and writing a book on earthquakes, took to Twitter to chime in on the study and place the findings into “context.”

“The chance of a San Andreas quake is up slightly, IF a Garlock quake happens because of Ridgecrest, and IF this model is correct. It’s elegant, but assumes a reason for quake triggering that is not consensus.”

Nonetheless, the looming threat of a major earthquake along the San Andreas fault is always a very real and unpredictable possibility, she said.

“The possibility of a San Andreas quake AT ANY TIME should already be part of your planning or you shouldn’t be in California,” Jones wrote.