Earthquake scientists are hoping to build an early-warning system for Washington, Oregon and California. It would give typically about five to 30 seconds of notice that a big quake was starting. The scientists have been meeting this week to craft a proposal.
There’s no way to predict earthquakes. But once a big one starts, it sends out different kinds of shock waves that move at different speeds. One type is fast-moving, but barely perceptible. These are called P-waves. They arrive before the slow traveling but damaging shock waves (called S-waves).
So, if you have precise sensors, they can detect the fast-moving waves and send out alarms.