US tests early earthquake warning system

The United States is testing an earthquake early warning system in California. The alert system, still rather crude, has been tested quietly by the US Government since February, reports CBS News.  

The messages are not yet broadcasts to residents or businesses, however, an elite group of scientists has been receiving the warning. The system currently gives people a five, ten, or 15 second warning about the earthquake.

It isn't designed to help people scramble out of their homes, but rather, to give people the time to get somewhere safe, fast.

Japan, Mexico and other countries prone to earthquakes have all fashioned their own early warning systems. According to the Daily Mail, when Japan was hit by the earthquake in March, millions of people got tens of seconds of warning beforehand.

"You want to get under a sturdy table before things start falling off the wall," said University of California, Berkeley seismologist Richard Allen, who is working with the project. "We don't want people to start running out of buildings."

The system, which works via a web of underground sensors, detects the primary waves of an earthquake before the secondary waves- which is what causes the damage.

The time between the warning and the earthquake striking, depends on the person's distance from the epicenter- the further away, the more time, explains NPR.

What can this do?

CBS News reports:

Trains can be slowed or stopped. Air traffic controllers can halt takeoffs and landings. Power plants and factories can close valves. Schoolchildren can dive under their desks and cover their heads.