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If you're in an earthquake-prone area and own an Android phone, it could save your life. It may even have already done so. The Android Earthquake Alert (AEA) system, which began in the U.S. in 2020 and has since expanded globally, sends an automatic alert approximately one minute before the ground starts shaking. That can be enough time to take cover or warn others nearby.

In a new paper in Science, Google explains how its detection system, which is built into most Android phones, works. They also share insights from its first years of operation and the improvements they've made.

Between 2021 and 2024, the AEA system sent warnings to millions of people in 98 countries. This included more than half a million people in Turkey and Syria who received an alert on February 6, 2023, just before a magnitude 7.8 earthquake struck. Overall, Google's researchers report that alerts were issued for 1,279 events, with only three of them being false alarms, two of which were triggered by thunderstorms.

Users were also surveyed, with 85% of those who received alerts experiencing shaking. Specifically, 36% of respondents received an alert before the shaking began, 28% during the shaking, and 23% after the shaking started. This writer received an alert on Monday morning at the same time as a 5.5 magnitude earthquake struck southern Spain.

How your phone can detect earthquakes

So, how does Google's system work? Just like traditional detection systems, Android phones detect P and S waves that radiate out from the epicenter of an earthquake. When a phone detects the waves, it sends the data and an approximate location to Google's servers, which search for the seismic source. Once it identifies the source with sufficient confidence, it sends out the alerts. Some people will receive these before the earth starts moving because electronic messages travel faster than seismic waves.

"AEA demonstrates that globally distributed smartphones can be used to detect earthquakes and issue warnings at scale with an effectiveness comparable to established national systems," the researchers wrote.

One of the advantages of the AEA is that it doesn't need dedicated seismic detection infrastructure, making it invaluable in regions that don't have an established warning network. The system now sends out an average of 60 alerts a month to around 18 million users.

Addressing challenges

Google's paper also highlights failings in their technology and steps taken to improve it. For example, during the 2023 Turkey-Syria earthquake, the system underestimated its magnitude, and warnings were only sent to some people after the shaking had started. Others didn't receive an alert at all. So, the Google team went back and tweaked their algorithm, and then tested it on the same earthquake data from 2023. They found it would have sent 10 million "take action" alerts.

Android Earthquake Alert is not designed to replace traditional systems, but rather to supplement them. Google says it will continue to work on AEA to improve warning times for future quakes.

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