Earthquake Prediction: Haicheng, China - 1975

Winter, 1975: Chinese officials ordered the evacuation of Haicheng (population about 1 million)

Reason: Reports from scientists and other observers:

      Over a period of months, changes in land elevation and ground water levels

      Widespread accounts of peculiar animal behavior

      Regional increase in seismicity (which later was recognized as foreshocks) had triggered a low-level alert.

      Increase in foreshock activity triggered the evacuation warning.

February 4, 1975: Magnitude 7.3 earthquake struck the region a few days after evacuation.

      2,041 people died; 27,538 were injured.

      It was estimated that the number of fatalities and injuries would have exceeded 150,000 if no earthquake prediction and evacuation had been made.

However…

      July 28, 1976: A magnitude 7.6 earthquake struck the city of Tangshan, a city with approximately one million inhabitants, without warning.

      None of the precursors observed near Haicheng were observed this time. 250,000 fatalities and 164,000 injured.