Officials reassess threshold to alert public to quakes, as some ready for the ‘Big One’
By Jim Carlton, Ethan Millman and Erin Ailworth | The Wall Street Journal
In the aftermath of Friday’s magnitude 7.1 earthquake felt throughout much of central and southern California, shaken residents are questioning whether they are prepared for a more dangerous one and why their phones didn’t send any warning alerts.
Los Angeles Mayor Eric Garcetti unveiled the ShakeAlertLA app, the nation’s first earthquake warning system available to the public, in January. Nearly 700,000 people have downloaded it to receive notifications based on their locations, according to officials.
But on Friday, when seats in Dodger Stadium vibrated and rides at Six Flags Magic Mountain theme park just north of L.A. shook, ShakeAlertLA did nothing, creating widespread frustration and confusion.
Alyssa Feller was being seated with her family at a restaurant in the L.A. suburb of Burbank on Friday night when she felt a jolt and saw a chandelier light fixture shaking. “I thought the app was broken, maybe not fully functioning,” said Ms. Feller. “Even if it gave a five-second warning, that would have been five seconds to find shelter or protection.”
In the hours following the quake, social media was full of screenshots of ShakeAlertLA devoid of any notifications.
The magnitude 7.1 earthquake near Ridgecrest is expected to produce many aftershocks in the weeks to come.
Officials behind the app, which Los Angeles developed using seismic technology from the U.S. Geological Survey, said the shaking in Los Angeles County didn’t reach the lowest threshold likely to result in major damage, equivalent to a magnitude 5.0 quake.
Seismologists say there is a danger of setting alerts too low, because people could get too accustomed to them and fail to take action when a major quake hits. California has 60 to 70 earthquakes a day, normally, and likely had hundreds of aftershocks on Monday, said Egill Hauksson, a geophysics professor at the California Institute of Technology’s Seismological Laboratory. Nearly all are too small to be felt by humans.