Puget Sound 4.0 quake offers hope for early warning system

The earthquake that shook the Puget Sound area Wednesday morning was good news for seismologists developing a new early warning system.

Just seven seconds after the 4.0 magnitude quake began deep below the earth’s surface in Kitsap County around 3 a.m., seismologists from California to Seattle were awakened by alarms triggered by an experimental earthquake warning system.

The system, being developed by the University of Washington, would do little to warn those near the epicenter of a quake, but it could provide precious time farther away.

It works by detecting primary waves, or P-waves, which travel through the earth at almost twice the speed of a quake’s destructive S-waves that cause actual shaking.

“So that’s enough time that if it’s a bigger earthquake, you could have the doors open on the firehouse, you could have the elevators stop on the next floor and open the doors, you could have warnings generated to schools to duck, cover, and hold,” says Bill Steele with the Pacific Northwest Seismic Network at the University of Washington.

Researchers are operating a prototype of the ShakeAlert system now in California, and hope to begin rolling one out in the Puget Sound area next year.

The system successfully sent warnings from this summer’s Napa quake to scientists along the network up to 10 seconds before shaking was felt miles away in Northern California, Steele says.

“The Bay Area Rapid Transit is using these alerts to stop their trains when strong shaking threatens that system,” Steele says. “So we’re using it in an experimental way now and sending it out to other businesses and emergency managers to reduce losses,” Steele says.

The initial focus of the system here would be on the rapid and accurate detection of Cascadia subduction earthquakes offshore, the source of massive 9.0 temblors once every 500 years or so, Steele says.

“For those, we think we can give 30 seconds to up to five minutes of warning that strong ground motion is on the way. That’s pretty exciting for us,” he says.

Steele says the goal is to one day create a system covering the entire West Coast. But the project needs about $80 million in funding, and so far has received only about $10 million, mostly from a private foundation, California’s Contra Costa Times reports.

“That’s really quite modest. I think we can definitely make a strong case for the cost-benefit even just looking at potential damage without loss of life in a larger earthquake,” Steele says.