The US Geological Survey’s earthquake early warning system now covers the entire West Coast. As of Tuesday, residents in Washington will start receiving mobile alerts when an earthquake is about to hit, giving them a few moments to prepare. The ShakeAlert system debuted in Los Angeles in 2018. It expanded to the rest of California the following year and Oregon this past March.

“Systems powered by ShakeAlert can turn mere seconds into opportunities for people to take life-saving protective actions or for applications to trigger automated actions that protect critical infrastructure,” USGS acting director David Applegate said in a statement.

ShakeAlert provides a heads up to more than 50 million residents of the West Coast when they’re about to feel the effects of a distant earthquake. They will receive warnings of between a few seconds and potentially over a minute. As the Los Angeles Times notes, that could be enough time for people to prepare themselves, elevators and trains to brake and surgeons to step back from patients in operating rooms.

Google sends early warning alerts directly to Android devices in the three states. Two third-party apps powered by ShakeAlert, MyShake and QuakeAlertUSA, are available on both iOS and Android. It’s probably worth downloading both in case there’s ever an issue with one of them.

The ShakeAlert system took over 15 years of planning and development, and it arrives several years after similar systems in Mexico, Japan and Taiwan. It sends alerts to mobile devices in an area where an earthquake of at least 4.5 magnitude is detected and it’s expected to cause shaking you can feel indoors, at least as strong as the effect of a truck driving by.