Napa quake gives warning system an early test

The temblor that rocked

California’s wine country this weekend gave researchers at U.C. Berkeley a chance to gauge the effectiveness of an experimental earthquake alert system. They say

it worked.

Ten seconds before Napa and surrounding areas began to shake, an alarm started squawking inside a Berkeley lab.

The system is not yet available to the public. State officials say it should be ready in the next few years. The federal government agreed earlier this year to chip in

$5 million to speed development. Similar systems are already up and running in Japan and Mexico.

The system works because sensors that detect earthquakes can send warnings at the speed of light, while the quakes themselves travel more slowly, at the speed of sound.

Geologists say a detection system could potentially warn L.A. 40 seconds or more before a big quake on the San Andreas Fault.

Read more from the U.S. Geological Survey about the Earthquake Early Warning System.