Just before the magnitude 6 Napa earthquake hit, Berkeley resident Joshua Bloom and his family woke to this.
Light shaking expected in one second.
[NOISE] The alert came from an earthquake early warning prototype.
Tinkered together by Bloom for less than a $100.
They're all off the shelf parts.
We needed a brain.
And so we needed a computer.
And there's a great hobbyist computer called Raspberry Pi which costs about $35 dollars.
Bloom added components including a battery and configured the device to search for other networks if needed.
So it can provide alerts about aftershocks.
Even if a quake knocks out power and networks.
But, the key to making the device work is shake alert which relies on seismic networks along the west coast.
Bloom, A U.C. Berkeley professor, is one of the system's beta testers.
When an earthquake begins the energy radiates from somewhere deep in the earth.
And so what we do is we use sensors at the surface of the earth to very rapidly detect the beginnings of the earthquake and we know the earthquake's underway.
We can predict.
The size of the earthquake and then push out the warning.
So we're using that earliest energy that most people don't feel to then predict the stronger shaking that's going to follow.
A five second warning is enough for people to take cover under a sturdy table but depending on the magnitude and distance from the epicenter.
Shake Alert could provide up to a minute of warning.
Bloom has shared an on-line tutorial for anyone interested in building their own device.
The only major problem, of course, is that this Shake Alert network is not yet open to the public.
It's still in beta.
So it's be, you know, kind of me handing you a fancy new i-phone, but not having any network on for you to be able to connect.
Other beta testers include the Northern California BART system.
With a ten second warning, BART can bring some trains to a complete stop.
A crucial step for avoiding a possible derailment.
During heavy commute, we have 63 trains that are running.
And many of them are ten car trains, and we have that many people.
We have a hundred people per car.
Seismologists are pushing for funding of Shake Alert, so alerts could be sent to cell phones and more.
If Shake Alert does become publicly available, devices like Bloom's may be as common as smoke alarms.
In Berkeley, I'm Simi Dass, www.c/net.com for CBS News.