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1996年3月—1997年4月间,新疆伽师西部相继发生6.9级强震与由7次6—6.6级子震所构成的强震群。历史上伽师及邻区曾发生多次强烈地震,导致伽师及邻区包括塔里木盆地周缘地震强烈活动的原因,是印度岩石圈块体快速北向运动造成的SN向强烈挤压与欧亚岩石圈块体缓慢向西运动所引起的左旋走滑的联合作用及其相关的现今不同方向、不同性质的断裂活动。区域性EW向盆缘活动断裂控制盆缘大型地震活动带的空间展布,盆缘EW向主干活动断裂与其他方向次级活动断裂的交叉复合部位是强烈地震发震的有利部位。伽师强震群子震震中分布受塔里木盆地西缘近SN—NNW向隐伏深断裂及其与EW向盆缘活动断裂的复合所控制。伽师强震群发生之后,在原强震群震中处发生7级以上更大地震的可能性很小;但由于塔里木盆地及其周缘,自1996年起已进入一个新的地震活跃期,在伽师附近及其南侧或东侧,近年内发生6—7级以上强烈地震的可能性较大。
From March 1996 to April 1997, a series of strong earthquakes consisting of 6.9 strong earthquakes and 7 strong earthquakes of 6-6.6 earthquakes occurred in the western Jiashi area. Historically, many strong earthquakes occurred in Jiashi and its neighboring areas, resulting in strong earthquake activity in the periphery of Jiamusi and its adjacent areas, including the Tarim Basin. The reason for this is the intense SN compression caused by the rapid northward movement of the Indian lithospheric block and the intense compression of Eurasian rocks The synergistic effect of the left-lateral strike-slip caused by the slow westward movement of the ring block and its associated fault activity in different directions and of different nature at present. The regional EW controlled the basin-wide active faults to control the spatial distribution of the large-scale seismic activity belts, and the intersections between the EW-trending active faults and the sub-active faults in other directions are favorable sites for strong earthquakes. The epicentral distribution of the Jiashi strong earthquake swarm is controlled by the SN-NNW trending concealed deep fault in the western margin of the Tarim Basin and its combination with the basin-edge active faults in the EW. After the Jiashi strong earthquake swarm occurred, it is highly unlikely that a large earthquake of magnitude 7 or above occurred in the epicenter of the original strong earthquake swarm. However, due to the active seismicity period of the Tarim Basin and its periphery since 1996, In the vicinity of the division and its south or east side, there is a high possibility of a strong earthquake of magnitude 6-7 above in recent years.