Earthquake Early Warning

Japan's early warning system exploits one fact: electronic signals travel faster than seismic waves. The moment sensors detect a quake, alerts race ahead at the speed of light.

Tokyo residents can get 10 to 30 seconds of warning before shaking arrives — enough time for trains to brake, factories to stop machines, and people to take cover. Mexico City's system can offer up to 60 seconds because the city sits far from the offshore fault zone. Those seconds shut gas lines and open elevators at the nearest floor, saving lives.