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In major milestone, US earthquake early warning system now covers entire West Coast

Rong-Gong Lin II, Los Angeles Times on

Published in News & Features

SAN FRANCISCO — In a major achievement years in the making, the U.S. earthquake early warning system will now be able to issue alerts to cellphone users anywhere on the West Coast of the continental U.S. beginning Tuesday.

On Tuesday at 8 a.m., mobile users in Washington state finally gained access to the earthquake early warning system’s mobile alerts. The alert system for mobile users was launched in Los Angeles in late 2018, and was expanded across the rest of California in late 2019. In March, Oregon mobile phone users began getting access to earthquake early warning system alerts.

The announcement means that anywhere from the Canadian border to the Mexican border, cellphone users are eligible to get early warnings that could give seconds to perhaps more than a minute of warning that shaking from a distant earthquake is on its way. The system works because the speed of today’s communications systems is faster than the speed at which shaking waves move through the ground.

“Now all three states will have alerts delivered to the cellphones,” said Robert de Groot, a U.S. Geological Survey earthquake scientist and communications coordinator for its ShakeAlert early warning system.

Because smaller earthquakes are far more common than the most powerful, catastrophic quakes, if residents get an alert, they’ll likely have a few seconds of warning before shaking arrives from a distant quake. That could be enough time for people to drop, cover and hold on, and for automatic systems to send alerts to hospitals telling surgeons to remove scalpels from patients; elevators to stop at the nearest floor; and trains to start slowing down, decreasing the risk of a derailment.

The earthquake early warning system could also give residents in the Pacific Northwest as much as 80 seconds of warning ahead of shaking from a magnitude 9 earthquake along the Cascadia Subduction Zone, a monstrous fault zone hundreds of miles off the West Coast, stretching under the Pacific Ocean from west of California’s Cape Mendocino to west of Vancouver Island.


The Cascadia Subduction Zone last ruptured in such a quake on Jan. 26, 1700, and sent catastrophic tsunamis not only to the Pacific Northwest, but thousands of miles away to Japan.

The U.S. is relatively late in developing an earthquake early warning system. Such systems have been in place for years in Japan, Taiwan and Mexico, with development usually beginning or accelerating after catastrophic death tolls from past earthquakes. The U.S. system, however, gradually began to gain bipartisan political support without a deadly quake sparking action, with initial efforts jumpstarted by a grant from the Palo Alto-based Gordon and Betty Moore Foundation.

The reach of the earthquake early warning system’s mobile alerts expanded last year with an update to Google’s Android mobile operating system. Google now funnels earthquake early warning alerts directly to Android cellphones in California, Oregon and, with Tuesday’s announcement, Washington.

(Apple has not made an agreement with the USGS to develop a similar system for iOS devices.)


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