Located at the mid-section of the north-south seismic zone in China, the Minshan block was resulted from the reverse and over-thrust movement of the Minjiang fault and the Huya fault from west to east. Under the background of a regional main compressive stress field with NWW direction, the Minjiang fault shows an obvious reverse and overthrust movement with some sinistrogynic slip components, while the Minshan block has strongly uplifted since Quaternary. The aerial photo interpretation and field survery on geology and seismology indicate that the Mingjiang blook is composed of several secondary faults with echelon pattern, among them, the row distance of Gamisi Chuanpan dextral echelon part is 3 km, which perhaps controls the secondary seismic rupture unit. Research by the geological landform formation history and rupture landform shows that the average vertical slip rate of the Minjiang fault is 0.37～0.53 mm/a, the horizontal slip amount is similar to the vertical slip amount since late Quaternary, the average lift rate of Minshan Block is 1.5 mm/a since Quaternary. It is suggested that M≥6.0 earthquakes occurred mainly on the border faults of the strong blocks, while middle and small earthquakes often took place on the faults with nearly east-west direction and new tectonic lift, which are associated with the active features of these faults.

We have studied the magnitude,epicentre of recent earthquakes,and spacial distribution of ground seismic ruptures on the Ganzi-Yushu fault. We have estimated the tendency of major earthquakes for each segment of the Ganzi-Yushu fault zone in the future 50 years by using the probability model of the general distribution for repeat time of characteristic earthquakes (Nishenko and Buland,1987). Our results show that the Manigange segment has high risk of recurrence of large earthquakes in the future 50 years. The possibility of major event recurrence on the Dangjiang segment also exists. These estimates can provide a basis for the long-and mid-term earthquake prediction for this region.