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2018-11-01. California’s new earthquake warnings deliver critical seconds of notice.

posted Nov 4, 2018, 7:44 PM by Alan Gould
By Paul Voosen, Science Magazine. [https://www.sciencemag.org/news/2018/11/california-s-new-earthquake-warnings-deliver-critical-seconds-notice] For GSS Energy Flow chapter 2. Excerpt: For years, ShakeAlert was an academic side project of California seismologists, especially the gravelly voiced Heaton, now at the California Institute of Technology (Caltech) in Pasadena, and Richard Allen, his soft-spoken counterpart at the University of California (UC), Berkeley. They were inspired by warning systems in Mexico, Japan, Taiwan, and Chile, among others, which emphasize detecting earthquakes at the source and warning distant cities before the seismic waves arrive. Many people thought such a system would be useless in fault-riddled California, where earthquakes seem to erupt underfoot anywhere. But Heaton and Allen persevered, deploying a pilot system in 2012. ...Los Angeles Mayor Eric Garcetti pledged: "By the end of 2018, we will deploy an earthquake early warning system to every corner of this city—in schools, at businesses, even on your smartphone." This year's version doesn't quite measure up to that promise. Only half of the system's 1675 seismic stations have been installed. The technology to rapidly push alerts to mobile phones is not mature. And the public has yet to be trained in how to respond to such alerts, which are sure to include false alarms. ...USGS has set one important parameter: Instead of waiting until a risk is severe, ShakeAlert will skew toward more alerts, sounding an alarm once a location is at risk of "light shaking." That will increase the warning time—but it also will mean that, if the rupture grows, the prediction could change to severe shaking only seconds before hitting. And the public might grow complacent about those alarms and fail to respond to the rare mild threat that, in a moment, turns severe....