Retrospection on the Conclusions of Earthquake Tendency Forecasts before the Wenchuan M8.0 Earthquake

The reason that the failure to forecast the Wenchuan M8.0 earthquake is studied,based on systematically collecting the seismicity anomalies and their analysis results from the yearly earthquake tendency forecasts between the 2001 west Kunlunshan M8.1 earthquake and the 2008 Wenchuan M8.0 earthquake.The results show that after the 2001 west Kunlunshan 8.1 earthquake,the earthquake tendency estimation for Mainland China was that strong earthquakes are in active stage and strong earthquakes of magnitude 8 were anticipated,but the phenomena that many large earthquake occurred around Mainland China,while there were a 6-year period of M7 earthquake quietude and a obvious quietude of M5 and M6 earthquakes during 2002—2007 in Mainland China,caused the distinctly lower forecast estimation of earthquake tendency in Mainland China after 2006.The middle part in the North-South seismic belt has been designated a strong earthquake risk area in recent years,but,the estimation of the risk degree in southeastern China was insufficient after the Ning′er M6.4 earthquake in Yunnan in 2007.There is no recorded earthquake with M7 in the Longmenshan seismic belt,which is one of the reasons that this seismic belt was not considered an important seismic risk area in recent years.