🤖 Google Turned Millions of Smartphones into Earthquake Detectors
When an earthquake strikes, the first to arrive are fast-moving and usually harmless P-waves. The real danger comes a few seconds later with the slower, more destructive S-waves.
To detect these early signals, the Earthquake Alerts System in every Android smartphone uses the accelerometer, the same sensor that rotates the screen.
When a phone detects suspicious shaking, it sends a signal with its location to Google's servers. Algorithms then analyze data from thousands of nearby devices. If multiple phones report the same movement, the system confirms an earthquake, pinpoints the epicenter, and estimates the magnitude.
That means people in affected areas can get 10 to 60 seconds of warning before the strong shaking begins—just enough time to duck under a table, get off a ladder, or move to safety ⤴️
⚠️ Does It Work?
Between 2021 and 2024, the Earthquake Alerts System detected over 11,000 earthquakes in 98 countries. Early warning coverage expanded from 250 million people to 2.5 billion.
Out of 1,279 alerts, only three were false alarms, two of which were caused by major thunderstorms. Even professional seismic networks occasionally make similar mistakes.
Google's system adjusts for local geology, building types, and differences between phone models. Today, the average error in estimating magnitude is just 0.25 points.
