Scientists still can't predict an earthquake. The U.S. government, however, has a warning system in the works that it hopes could quickly send out a widespread alarm before most people feel a rumble — and save lives when seconds count.
The recently upgraded network of seismometers and computers, known as ShakeAlert, is advancing through the prototype-testing stage, Sally Jewell, secretary of the U.S. Department of the Interior, said at a news conference Tuesday.
When fully operational, she said, ShakeAlert will have "the ability to provide notice to people before that earthquake strikes."
Getting to that point will still take a lot of work , according to Peggy Hellweg, one of the system's creators and a seismologist at the University of California, Berkeley, in the heart of quake country.
The goal is to send an alert almost instantly. Up until now the system has simply been too slow — "not good enough to do the job for all of the earthquakes that we expect in California and the Pacific Northwest," Hellweg told me when I called.
When a quake hits, the first of many seismic waves that rocket through the Earth is called a P wave. It doesn't do the major damage — that comes from later waves. But it carries information about the quake. Seismic sensors can detect that P wave and relay the information to computers. The computers calculate where the quake hit and how big it is. Then they send out warnings.
Unfortunately, all this can take up to dozens of seconds, losing valuable time for people to duck, cover and hold on before the later, damaging waves — S waves — get to where the people are.
"We want to be able to tell people, 'There's this big earthquake, it's happening, and it's going to affect your area,' " Hellweg said.
That's what ShakeAlert is all about. Federal officials say the upgraded system — with more sensors and more, faster computers — should cut that processing time to just a few seconds, at most.
That's how Japan's system works.
I saw it in action after the quake in 2011 near Fukushima. I was doing an interview in Tokyo, and suddenly my translator grabbed his cellphone, which was squealing in an odd way.
"I think this is an earthquake — an earthquake in Fukushima," he told me. We waited, rather nervously, and in about 10 seconds, we felt the rumble in the Earth — it was an aftershock of the big one that had hit days earlier.
I should confess that even though we got a warning, we didn't react the way we should have.
"Did you all drop, cover and hold on?" Hellweg asked me when I told her of my experience in Japan.
"Uh, frankly we did not," I admitted.
ShakeAlert eventually will link to smartphones in the U.S. But the warnings won't work unless people react the way they're supposed to. And, among other things, that requires faith that the warnings are accurate.
John Vidale, a seismologist at the University of Washington and head of a local seismic network in the Northwest, is helping to create ShakeAlert. He said it needs two more years of work to build reliability.
"We don't really want to send it out until we have enough confidence that it won't misfire," he said.
False alerts happen, even in Japan. Officials there recently warned of a big quake that didn't happen; they had to go on TV and apologize.