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.

Along the valley of the Fubian river,which is located at Mucheng Lianghekou of the Maerkang region in Sichuan Province,there is a hidden fault of NW trending——the Fubian River fault. Occurrence of three major earthquakes during 1989～1991 is associated with this fault. Field investigations and analytical calculations demonstrate that it is one of the fractures in the arc shape structure of the inner Sichuan-Qinghai block. Since Quaternary the activity of this fault is characterized by variant distribution in space and time. Accordingly it has evident marks of segmentation. Under the recent regional stress field this fault has dominant movement of strike-slip. At the southeast end of it. where the trend of the fault changes,a local area of extension occurs.