Tiny cracks in rocks near an impending earthquake can be detected using tiltmeters as the cracks fill with water, lowering nearby water levels, and increasing radon gas levels escaping from rocks. Animals also start behaving strangely close to an earthquake. Cities plan by establishing earthquake centers, practicing school drills every 3 months, and reinforcing all buildings. While earthquakes are hard to predict precisely, scientists in China predicted a 1976 quake but were disbelieved when they could not provide an exact date, resulting in 250,000 deaths when a magnitude 7.8 quake hit Tangshan City.

1. Limiting the damage of Earthquakes.