An earthquake which struck in western China on 12 February 2014 is just another in a series of inevitable natural disasters; events which we can expect but not forecast. But this week’s earthquake calls to mind another, in 1975, which authorities did successfully predict – and as a result, remarkably few lives were lost.
The Haicheng Earthquake of 1975
On 4 February 1975, the authorities in Haicheng, China, announced that a major earthquake was imminent and began an evacuation of many thousands of people from what they considered vulnerable areas.
When an M7.0 earthquake struck later that day, it devastated much of the city of Haicheng and its surrounding region. In spite of this devastation, the death toll of just over 2,000 people was far lower than the estimated 150,000 who otherwise might have died or been injured, according to United States Geological Survey (USGS) Historic Earthquakes.
The exact details of the prediction included complicated parts and drew on extensive data. In their exhaustive consideration of the process, Kelin Wang and his colleagues Qi-Fu Chen, Shihong Sun and Andong Wang identified certain key stages; specifically that there were two medium-term predictions based upon a series of foreshocks. Scientists also took account of other potential earthquake precursors, such as changes in ground water levels, ground deformation and even animal behaviour.