We've reported on it before, but in the wake of the Japan earthquake, and a two-day meeting of seismologist at UC Berkeley, there's a renewed push to get an earthquake early-warning system set up in California. Japan had such a system, and it was able to give people in Tokyo 25-30 seconds to take cover before the March 11 earthquake struck. Nearer the epicenter, in Sendai, they only had about five seconds warning, because this early warning system is, actually, a little limited. (Unlike this guy's prediction methods, which give us days or weeks warning but are generally wrong.)

Those critical seconds, scientists say, could be enough to "stop or slow trains enough to avert derailments, halt surgeries, open elevator doors and warn students and workers to seek safety." The warning in Japan was transmitted to computer screens and schools across the country. A system here may include notifications sent to cell phones as well.

They say it will take five years and about $80 million to fully implement the system, which has already been launched in prototype form with 400 sensors statewide. "It's our hope that it won't take a killer earthquake in the U.S. to realize this system," says Doug Given, earthquake early warning coordinator at the U.S. Geological Survey.

Below, a sample warning from Japan. Watch the volume...