The prediction resulted from the synthesis of many types of investigation, but the main methods used for long-, mid- and short-term prediction appear to have been based on studies of seismicity, deformation and foreshocks respectively.

The Haicheng earthquake is the "first, and so far only, case where a large earthquake was predicted," says Susan Hough, a seismologist with the U.S. Geological Survey in Pasadena, Calif.

the prediction was "a blend of confusion, empirical analysis, intuitive judgment, and good luck."

some Chinese officials made "imminent" predictions, based on an increase in foreshock activity in the 24 hours before the main shock.