Rep. Peter DeFazio (D-OR) convened a group of scientists and policymakers Tuesday to discuss the path forward for the West Coast’s fledgling earthquake early warning system.

The existing system, called ShakeAlert, is a collaboration of the U.S. Geological Survey, the State of California, and a coalition of universities across California and the Pacific Northwest.

It uses land-based monitoring stations to detect waves – called P waves – that travel through the earth and signal an arriving earthquake, and then send an alert seconds to minutes before the heavy shaking starts.

ShakeAlert is in a pilot phase, and the alerts only go to a small group of test users, including utilities, emergency managers, and state and city governments.

Here are three things we learned from the experts’ discussion of earthquake early warning systems.

1) Upgrading ShakeAlert is a relative bargain.

The USGS plans to upgrade and build 150 seismic sensors to improve the speed and reliability of ShakeAlert’s warnings. Building out the existing land-based ShakeAlert system will cost about $38 million, and operating it will cost an additional $16 million a year.

By contrast, some scientists suggested the U.S. should be adding more offshore sensors on the sea floor. That type of monitoring system could provide a slightly earlier warning of a major quake — perhaps 10 seconds faster than the terrestrial system — and it could alert people how large a coming tsunami would be. It would also contribute significantly to geologists’ ability to study the Cascadia fault.

Scientists at the roundtable said based on a very preliminary assessment, building an offshore warning system would cost $400 million — 10 times the price tag of the terrestrial system.

2) Education and outreach are key

Several people pointed out that an early warning system only works if the people in the Northwest who receive the alert are trained and know what to do when the shaking starts.

“We stand to create more confusion around the messaging rather than solving the problem,” said Jay Wilson, the resilience coordinator for Clackamas County.

“If people have tens of seconds of notice, they may decide to act differently. That may not be bad, but if they’re in a brick building that might not allow them to get out, it creates potential conflicts,” he said.

Participants also stressed the importance of building the system in collaboration with businesses and industries in the Northwest, and to develop automated systems that could do things like slow down trains and help manage the power grid in case of a mega quake. 

3) Early warning systems have their limits

An 8- or 9-maginitude Cascadia quake will affect a huge area, potentially stretching from Northern California to Canada.

The advance notice people would receive before a Cascadia quake would largely depend on their distance from the epicenter. Those closest to it might receive the alert just a few seconds before the heavy shaking started, while communities farther away could receive minutes of advance notice.

As a result, some people argued an early warning system does very little for communities on the Oregon Coast, which could be very near the epicenter of the quake. The coast already has a tsunami monitoring and alert system in place.

Others disagreed, and argued that an early warning system could give Oregon coastal towns critical time to evacuate early, given that the quake’s epicenter could lie well to the north of the Oregon coast.