Expert says California earthquake picked up by early warning system

ByWayne Freedman KGO logo

Wednesday, October 16, 2019

Expert says California earthquake picked up by early warning system

Dr. Angie Chung specializes in sending early warnings received from stations. Monday night's quake was too small and too close the system to have been effective.

BERKELEY HILLS, Calif. -- Two moderate earthquakes rocked the Bay Area in the last 24 hours. The first one hit around 10:30 p.m. Monday near the Pleasant Hill-Walnut Creek border. There have been at least 26 aftershocks since then, with the strongest being a magnitude 2.1. On Tuesday, we went deep into an abandoned mine to catch up with a quake expert.

About 150 feet under the Berkeley Hills, you'll find an isolated environment away from cars, trees and wind. As Seismology Professor Dr. Peggy Hellweg describes it, "Nothing is perfectly still but as close as you can get, yes."

Perfect to the extent that that when we speak...or even breath, ultra-sensitive instruments in this UC Berkeley seismology station record the vibrations. We came to talk about Monday night's quake when instruments registered another quake southeast of Hollister. Hellweg pointed at the squiggly lines. "It happened right while we were in here."

ABC7 ORIGINAL SERIES: 'The Earthquake Effect' provides in-depth coverage on Bay Area's readiness for the next major earthquake

So that's two earthquakes now in less than 15 hours.

"This is the quake that happened last night," said Dr. Angie Chung

Dr. Angie Chung specializes in sending early warnings received from stations like that one we'd just visited. Monday night's quake was too small and too close the system to have been effective.

"If you are on top of the epicenter, you will not receive much warning," said she said.

The system U.C. Berkeley is helping to develop will work similarly to proven systems in Mexico City and Japan. They read warning waves, or P waves, which move faster than shock waves, or S Waves. The farther the distance, there time that people have to prepare. It may make a difference when the Hayward Fault finally ruptures.

"If the Hayward Fault goes for 30 seconds at the site, how long will the shaking be 30 or 400 miles away?" we asked Dr. Hellweg.

"It can last a minute to two minutes," she said.

You read correctly. One or two minutes of violent, dangerous shaking.

VIDEO: What it was like to drive on the Bay Bridge as Loma Prieta hit

So, when can we get such an early warning system? Dr. Chung and Dr. Hellweg already have a beta version in their phones. It showed data from the Hollister quake instantly.

"The app says 160 miles away and 14 people say they felt it," said Dr. Hellwegm consulting her phone.

You can get the MyShake application here, it's free for Apple or Android devices.

Take a look at ABC7's in-depth coverage of the Loma Prieta earthquake here.

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