On the evening of February 4, 1975, a magnitude 7.3 earthquake occurred near Haicheng in Liaoning Privince in eastern China. Almost 90 percent of the structures in Haicheng, a city of 90,000 people, were destroyed or seriously damaged. Given the time of day, the subfreezing temperatures, and the population density in the city and the surrounding area, casualties of 100,000 might ordinarily have been expected. Yet the earthquake was predicted accurately enough to enable a massive evacuation of the local population from the city on February 4.
The prediction of the Haicheng earthquake was an extraordinary achievement by the geophysical workers of the People's Republic of China, whose national program in earthquake reserach was less than 10 years old at the time. To study the background to this prediction, a delgation of 10 U.S scientists, which I led, visited China in June 1976.