Predicting earthquakes, saving lives...

"When it comes to earthquakes, however, patterns are prone to pitfalls.


In 1974 the Chinese government -- responding to signs of an imminent earthquake, rising groundwater and erratic behavior in animals -- ordered the people of Haicheng out of their homes and into the street. Nothing happened.


Six weeks later they did it again -- and Haicheng was devastated by a 7.3 earthquake. More than 2,000 people were killed, but the precautionary evacuation of buildings was credited with saving 150,000 lives.


A year later, however, no one predicted the 7.6 earthquake that struck Tangshan, with a population of more than 1 million. That quake killed more than 250,000 -- perhaps as many as a half-million people."

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