California’s early warning system beat Napa earthquake by 10 seconds

See the original posting on The Verge

Ten seconds before the shaking started early Sunday morning, an experimental warning system in a UC Berkeley lab sounded an alarm, counting down to the impending earthquake. It was the biggest test yet for a promising earthquake alert system that remains stuck in budgetary limbo.

The warning works by outrunning earthquake

The system works by leapfrogging the earthquake. Sensors near fault lines detect the first sign of an earthquake — the faster moving but less destructive P-waves — calculate the severity of the quake, and broadcast a warning before the more destructive S-waves arrive. That means that areas near the fault in Napa wouldn’t have gotten any warning, but the Bay Area could have received several seconds notice. Depending on…

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