Earthquake early warning alerts became publicly available throughout California Thursday for the first time, potentially giving people time to protect themselves from harm, reports KQED-TV. The nation’s first statewide quake warning system coincides with the 30th anniversary of the Loma Prieta earthquake that ravaged the San Francisco Bay area on October 17, 1989, according to the account.
Warnings produced by the ShakeAlert system will be pushed through two delivery systems: a cell phone app called MyShake and Wireless Emergency Alerts (WEA), meaning people may receive both notifications.
Gov. Gavin Newsom, flanked by some of the state’s seismologists, announced the systems at a press conference Thursday. They cited the U.S. Geological Survey’s calculation that California has a 99.7 percent chance of being struck by at least a 6.7 magnitude earthquake within the next 30 years. Newsom called that a “jaw dropping” prediction. “That’s the reality we live in. … The price of admission to live here is preparation.”
Brian Ferguson, deputy director for crisis communication at the Office of Emergency Services, said the app, “is at a place now where we’re satisfied with the performance and the testing, which has been very well done. We think we’re at a place where it’s not perfect but we can keep people safe, and that’s our ultimate threshold,” reports KQED.
“The alerts will only go to people that are going to feel shaking,” said Richard Allen, director of the UC Berkeley Seismological Laboratory. MyShake is available for download to IOS users through iTunes and through GooglePlay stores for Android phones.
The ShakeAlert system does not predict earthquakes. Rather, it uses numerous seismic stations to detect the start of an earthquake and light-speed communications to send the data to computers that instantly calculate location, magnitude, and intensity of shaking, creating alerts to be distributed to affected areas. Depending on distance from the epicenter, the alerts may give warnings of several seconds to a minute before shaking arrives at a given location, according to KQED.
The MyShake system maintains a database comprised of which cell phones are in 10-kilometer-by-10-kilometer (6.2-mile-by-6.2-mile) cell grids and pushes the alerts to phones in zones where at least level three shaking will occur. That means receiving an alert is not based on which tower the phone is communicating with.
In contrast, WEA creates polygons that include cell phone towers, said Ryan Arba, chief of the seismic hazards branch of the Office of Emergency Services. Triangles, quadrilaterals, pentagons, and hexagons are all examples of polygons. “If your phone is currently communicating with that cell tower, the message will be broadcast to your phone,” he said. A person will get an alert if they are outside a polygon but their phone is communicating with a tower inside the polygon, he explained.
October 21, 2019
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