SEATTLE – When an earthquake happens, most of what you feel is from what's called "S" waves or sheer waves -- earthquake waves of energy that do the most damage. It's one of the things seismologists track.
But there's another kind of wave called the "P" wave or primary wave. It's much less damaging and it's the first wave. It can actually be picked up with sensitive instruments tied in with radios and satellites to help warn us that severe shaking is next.
An early warning system could stop trains in time before rails broke and bridges collapsed. It could trigger gates keeping any new traffic from getting onto Seattle's Alaskan Way Viaduct or the State Route 520 or Interstate 90 floating bridges.
Manufacturers like Boeing could shut down production and get employees to safe places.
"You'll have in the area of three minutes," to get ready in this scenario, said John Vidale, Director of the Pacific Northwest Seismic Network
Vidale helped promote this idea for an early warning system at a conference earlier this week at U.C. Berkely. It would be a three state system covering Washington, Oregon and Northern California.
The amount of warning will vary depending on distance. The closer to the start of the quake, the less warning you get – as little as 20 to 30 seconds to as much as a minute.