Ridgecrest Quakes In Southern California Have Increased Risk Of San Andreas Quake

The Ridgecrest Earthquakes That Struck Southern California Last July Have Increased the Risk of a ‘Big One’ Along the San Andreas Fault

Strange Sounds

This time last year, a series of powerful earthquakes struck Southern California, culminating in a magnitude 7.1 temblor and a set of aftershocks.

And according to a new study, those tremors may have inched the state closer to a much larger, deadlier catastrophe: A Big One along the San Andreas Fault.

Millions of people live in the area of the San Andreas fault which is overdue for a big earthquake

Buildings caught fire. Gas lines ruptured, and power went out. Deep fissures opened in the ground. A rockslide blocked off a highway.

Within a week, scientists recorded more than 3,000 quakes in the area around California’s Searles Valley.

And according to a new study, those tremors may have inched the state closer to a much larger, deadlier catastrophe.

That’s because the series of seismic events — dubbed the “Ridgecrest earthquakes” for the town near their epicenter — increased the chances of a large rupture on the San Andreas fault, according to two seismology researchers.

The San Andreas slices through 800 miles of the California coastline, from Eureka to San Bernardino. The fault long overdue for “the big one” — the term for a magnitude 6.7 or higher along that fault.

The big one will most likely crumble buildings, cause explosions from ruptured natural gas lines, trigger landslides, and collapse bridges.

The new research suggests that smaller earthquakes in California could trigger such a disaster via connecting fault lines.

A connecting fault line could trigger ‘the big one’

The new threat comes by way of the Garlock fault line, which runs 160 miles through the Mojave Desert and connects the site of the Ridgecrest quakes to the larger San Andreas fault.

The Garlock fault previously had an estimated 0.023% chance of producing an earthquake of magnitude 7.5 or greater in the next 12 months. But after Ridgecrest, the researchers calculated that those chances grew to 2.3% — a hundredfold increase.

If such an earthquake were to strike the Garlock fault, it could trigger a disaster along the San Andreas. That means there is a 1.12% chance of a large earthquake on the San Andreas within the year. That’s about three to five times as likely as in a normal year.

“The Ridgecrest earthquake brought the Garlock fault closer to rupture. If that fault ruptures — and it gets within about 25 miles of the San Andreas — then there’s a high likelihood, maybe a 50-50 shot, that it would immediately rupture on the San Andreas,” explained Ross Stein.