California earthquake early-warning system will mean false alarms. Still worth it, experts say
By Rong-Gong Lin II
Scientists at the U.S. Geological Survey, USC and Caltech worked on a research project, published Thursday, to determine the limits of the accuracy of seismic warnings. They conducted a statistical simulation to determine what strategy would be the best to save lives and protect the economy — is it better to get more warnings but also more false alarms? Or is it better not to receive an alert unless it's certain there will be shaking, even though that might cause you to miss a warning?
First, they found there was no way to have an earthquake early warning system that was 100% accurate. It's scientifically impossible. Earthquakes that produce the same amount of overall energy — those that have the same magnitude — can produce much different shaking.
Second, the scientists calculated that any particular California location on average had the chance of feeling an earthquake — a minimum of light shaking — just twice per decade.
And here comes their key finding: An early warning system that gives you an excellent chance of being alerted to those twice-in-a-decade earthquakes will likely deliver four warnings that turn out to be false within that same time period.
"It's a small price to pay," said research geophysicist Sarah Minson, "if you're talking about something where there's a lot of benefit to be had." For instance, a potentially deadly derailment could be avoided by slowing a train before the predicted shaking is set to arrive, said Minson, lead author of the study, on Thursday at the USGS office in Menlo Park, Calif.