Abstract: Basing on the new data from the detailed field work in the last few years,we conclude thegeometric and kinematic features of the seismic fault of the 1668 Tancheng earthquake(M=8(1/2))and then make a new understanding on its fracture mechanism. The 1668 seismic fault,as longas 130 km,was formed in middle of the Tanlu fault zone between Tuling,Juxian county,andYaoshang, Tancheng county.It consists of five secondary rupture segments with different modesof movement.The middle segments are dominated by strike-slipping, while the two ends bythrusting. The seismic fault was first ruptured at the centre,where the fault was strong shearing；Then the fracture propagated in two directions. The M=8(1/2) main shock was generated bythe initial rupture and during fracture propagating the aftershocks occurred.The fracture mechanism of the paleoearthquake events during the Holocene was the same.

Key words: Tancheng, Seismic fault, Fracture mechanism, Kinematic feather

摘要： 根据近年来野外考察所获新资料,总结了1668年郯城8(1/2)级地震断层的几何学、运动学特征,并对地震断层的破裂机制提出了新见解。1668年郯城8(1/2)级地震断层北起莒县土岭南至郯城窑上,全长130km,由5条运动性质不同的断层段组成。中部以走滑运动为主,两端部以逆冲性质为主。断裂首先在强走滑的中部产生破裂点,并向南北两个方向传播,造成了主震及强余震序列的发生。全新世以来多次主地震事件有着相同的破裂机制。

关键词: 郯城, 地震断层, 运动学特征, 破裂机制