The 2008 Wenchuan earthquake and earthquake prediction in China

摘要

For historical reasons, earthquake prediction in China is government sanctioned and law regulated. During 1966-1976, coinciding with the political and social turmoil of the Cultural Revolution, there was an explosion of earthquake prediction. Enthusiasm climaxed with the prediction of the 1975 Haicheng earthquake, a prediction that was due mainly to the occurrence of an unusually pronounced foreshock sequence and the extraordinary readiness of some local officials of the time to issue imminent warning. Since the catastrophic Tangshan earthquake in 1976, there has been diminishing confidence in prediction and increasing emphasis on seismic risk mitigation. The M_w 7.9 Wenchuan earthquake of 12 May 2008 once again demonstrated the gloomy reality of earthquake prediction. In spite of the installation of massive precursor monitoring networks and an elaborate schedule of prediction conferences, no anomalous pattern was identified before this earthquake that would have enabled its prediction. Instead, the Wenchuan earthquake overwhelmingly demonstrated the vital importance of seismic risk mitigation. Different from Tangshan 1976, where seismic design was not required, such design was required for the Wenchuan area in 2008. Buildings that met the design standard suffered much less damage than those that did not. Notwithstanding, progress in practice lagged far behind the promulgation of regulations; stricter enforcement of seismic design provisions and wiser selection of construction sites would have prevented many deaths and greatly reduced the destruction of property. The prediction program in China has provided useful experience and taught many lessons. The most important lesson is that, regardless of its future potential, it is presently impractical to rely on prediction to prevent earthquake disasters. The practical approach is to strengthen the resilience of our built environment based on an assessment of seismic hazard.