California’s 4th of July Earthquake Won’t Delay the “Big One”; May Have Increased Risk of Future Quakes

Cleanup continues at Eastridge Market in Ridgecrest, Calif., hours after a 6.4 magnitude earthquake shook the area. (Robert Gauthier / Los Angeles Times)
Cleanup continues at Eastridge Market in Ridgecrest, Calif., hours after a 6.4 magnitude earthquake shook the area. (Robert Gauthier / Los Angeles Times)

Does a good-size earthquake help relieve pent-up seismic stress? Does that postpone the day of reckoning when the Big One finally arrives?

That was the question some in California were asking hopefully in the wake of the July 4 magnitude 6.4 earthquake that rattled the region.

You won’t like this answer.

It’s wishful thinking to imagine that, as a rule, earthquakes “relieve” seismic stress, said seismologist Lucy Jones.

In fact, generally speaking, earthquakes actually increase the risk of future quakes.

Here is a primer on earthquakes and seismic stress largely based on past interviews with Jones and other scientists:

Does an earthquake immediately relieve seismic stress, forestalling a future big quake?

No.

Think about what generally happens after a decent earthquake. Aftershocks. Lots and lots of aftershocks. It’s going on right now in the area around the Fourth of July magnitude 6.4 earthquake in the Mojave Desert, close to Ridgecrest, a town of 29,000 notable for being a pit stop for Mammoth-bound skiers from L.A.

But couldn’t relieving seismic stress in one part of the state restart the earthquake clock elsewhere, so to speak?

No.

Consider: One part of California, west of the San Andreas, is constantly moving northwest, toward Alaska, relative to the other side of the Golden State, which is headed toward Mexico.

These immense forces are what generated the state’s mountains, from the ranges seen in the Los Angeles Basin to the hills lining the ridges of the Bay Area. There’s a reason why earthquake faults are often alongside hills and mountains.

“If you see mountains in California, that means something is moving up those mountains faster than erosion is wearing them down,” Jones said in an interview published last year. “Basically, when you see mountains, think earthquakes in California.”

It’s also the reason why California has been home to lucrative deposits of oil. It’s the reason where there are springs in the desert giving rise to places like Palm Springs.

There is no avoiding, eventually, big earthquakes being unleashed on faults somewhere in this state. We just don’t know exactly when or where it’ll happen. But just as it’s happened before in centuries and millennia past, it will happen again.

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SOURCE: RONG-GONG LIN II
The Los Angeles Times