In Mexico City, people know when an earthquake is coming—the city has had a warning system in place for decades. For example, in 2014, when a magnitude 7.2 earthquake hit, residents had more than a minute to prepare after getting alerts via TV, radios, and sirens.

Likewise, Japanese cell phones made after 2007 come with a built-in earthquake alert system. These warnings come from the country’s early warning system, which also broadcasts nationwide and can hit the brakes on bullet trains during big quakes.

But California doesn’t have an earthquake warning system. A network of 400 early warning stations has been operating there in research mode for years as part of the West Coast’s “Shake Alert,” but it is only halfway built. It lacks the funding to go full-scale.

Now seismologist Richard Allen at the University of California at Berkeley wants to develop a cheaper, more bare-bones system that could work in tandem with Shake Alert. Allen says your cell phones, and thousands of others around the world, could help power a different kind of earthquake alert. He released a new Android app on Friday to test the theory.

MyShake” is different from other earthquake warning systems, because it records shaking directly on smartphones. The system uses a phone’s accelerometers, the tiny chips that record movement and vibrations to orient phone screens, log physical exercise, and play games.

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In testing, MyShake was 93% accurate at detecting earthquakes. It notices quakes bigger than 5.0 magnitude, right about the level when they can start to cause real damage.

When a phone running MyShake senses a seismic event, it sends GPS data to the lab at Berkeley for analysis. In theory, the tech could turn that information around and issue an earthquake alert back to phones in less than a second—but this new app won’t do that just yet. For now, the app is only collecting user shake data, while also sharing bits of historical information about major earthquakes.

“It’s a citizen science project” Allen says. In order for it to become a real-time warning system he says, first, “we need to be able to record some real earthquakes.”

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The team that developed the new seismology tech at Berkeley was joined by developers from the Silicon Valley Innovation Center, which focused on ensuring the app won’t suck up too much battery life.

MyShake wasn’t just built for California techies, though. If the app takes off, thousands of cell phones around the world could operate like a network of tiny sensors, says Allen.

The software’s real power could be harnessed in countries where there’s no existing earthquake alert system, like Nepal. Last year, the country was rocked by a magnitude 7.8 quake that killed more than 8,000 people. With new technology like MyShake, the hope is that the country’s millions of smartphones will be able to anticipate the next big shake.