Major Earthquake Risk Back to Normal After Hundreds of Small Quakes

LOS ANGELES, CA -- The threat of a major earthquake devastating the Los Angeles area is back down to normal after a swarm of quakes rattling the Salton Sea area died down.

Throughout the last week, Southern California has been living under an increased threat of the Big One thanks to a swarm of more than 200 temblors epicentered less than four miles from the San Andreas Fault. During the peak of the swarm, the increased risk of a major quake along the San Andreas increased to 1 in 100, prompting a warning from the U.S. Geological Survey. Now, the likelihood of a major quake is back to the typical 1 in 10,000.

“The last earthquake we recorded in the swarm was yesterday morning,” said USGS Seismologist Morgan Page. “It’s pretty much died out by now.”

The swarm of quakes began early last week. In all, there were 214 small quakes, including a trio of larger quakes between magnitudes 4.0 to 4.3.

“The larger the earthquake, the greater the probably it will trigger a bigger one,” explained Page.

There hasn’t been a major quake on the San Andreas since 1690. On average, the San Andreas has a major quake every 300 years.

“We are a little overdue but that doesn’t mean an earthquake is imminent,” said Page.

According to recent quake simulations, a major quake along the San Andreas is estimated to claim roughly 1,800 lives, said Page. As Los Angeles implements new legislation requiring major earthquake retrofitting, the number of lives lost in a major quake will go down, she added.

City officials estimate there are 13,500 “soft-story” buildings -- which are commonly multi-story apartments with tuck-under parking spaces -- and an estimated 1,500 brittle concrete buildings in the city that may need to comply with the new law.

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