Abstract: Comparative study has been made for M≥5 Seismic Activities 10 years before some large earthquakes such as Wenchuan, Kunlunshan, Chayu and Haiyuan wintin an epicentral range of 15°. It is demonstrated that abnormal types of seismicity and magnitude can be calassified into three kinds, i.e. large area acitivity, quiescence and local acitivity, with abnormaly range about (600±200)km. Abnormaly distribution is controlled by boundary faults of Qinghai-Tebetan sub-plate. The increase or decrease of abnormal activity and strength is the most obvious around the future epicenter or nearby crust blocks, characterized by exceeding the historical maximum value and gradually decreasing outward. High values of annual cumulative frequency anomalies of M≥5 earthqukes mostly appeared 1 to 4 years before the mainshock in the study area. The epicentral regions of large M8 earthquakes are areas of weak or quiescent M≥5 activities, generally gap, some belts and the size of the gap positively related to magnitude.

Key words: Wenchuan M8.0 earthquake, M≥5 Seismic Activities, Comparative Study