Billions of phones can detect and warn about nearby earthquakes

Google’s Android Earthquake Alerts program is a globe-spanning earthquake early-warning system that uses billions of phone sensors to detect seismic shaking and alert those at risk

By Jeremy Hsu

17 July 2025

Early warnings can save lives before earthquakes like the 5.6-magnitude quake that killed and injured hundreds in Indonesia in 2022

ADITYA AJI/AFP via Getty Images

Your phone may be among the billions of devices worldwide that already serve as an earthquake early-warning system in dozens of countries.

Since launching in 2020, Google’s Android Earthquake Alerts system has expanded to enable 2.3 billion Android phone and smartwatch users to receive alerts about seismic shaking nearby, compared with 300 million people who may get such alerts from other sources, according to a new study by researchers at Google. But the phones aren’t just delivering warnings – their sensors also help detect earthquakes.

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“Billions of Android devices work together and act as mini-seismometers to create the world’s largest earthquake-detection network,” says Richard Allen at the University of California, Berkeley, who is also a visiting researcher at Google.

The system developed by Allen and his colleagues analyses vibrations detected by accelerometers in Android phones and smartwatches. Together, this network of sensors can indicate how large an earthquake is and which phone users are close enough to danger to receive a warning message.

Google’s system notifies people when it detects an earthquake with a magnitude of 4.5 or greater. But the system “cannot detect all earthquakes” because it requires that a large enough number of phones will be close enough to the quake, says Allen. For example, it doesn’t detect earthquakes originating from most mid-ocean ridges, although it can detect seismic events occurring tens to hundreds of kilometres offshore.