In the 2008 movie The Dark Knight, Batman taps into millions of cellphones, using them to triangulate the villain's location. It was a thoroughly science fiction notion. Today, however, the same idea is serving earthquake alerts. Batman's technology is, in essence, what the Android Earthquake Alerts (AEA) system does. Developed by Google, it uses feedback from millions of Android phones across the planet to warn people of an impending earthquake.

Nobody can predict when an earthquake will strike, yet we can sometimes detect them just before the main event with earthquake early-warning (EEW) systems. Countries like the US, Mexico, Türkiye, Japan, and China have EEW systems. But these are expensive to maintain and only cover small areas, leaving most of the planet and billions of people at the mercy of sudden tremors.