Your phone can now warn you before an earthquake arrives.

Yes, before…

This feat of science and personal technology is the best example I’ve seen of how smartphones can help protect tens of millions of us from significant danger. I’ll show you how to get it.

Known as ShakeAlert, America’s earthquake early-warning system was developed by the U.S. Geological Survey and partners to give you typically up to 20 seconds of advance warning before significant shaking arrives, or even a minute in extreme circumstances. If you’re close to the epicenter, you might not get much notice — but it could still be enough to protect yourself.

In the house or at work? 20 seconds can be time enough to get out.