从同震和震后形变分析1668年M8.5级郯城地震对周边地震活动性的影响

以山东郯城1668年大地震为例，以前人地表地质调查结果为约束，利用弹性位错理论初步获取了该地震的同震破裂模型；在此基础上，基于粘弹性分层模型分析了该地震的同震和震后形变，同时以主震断层为接收断层计算了库仑应力分布，进一步讨论了地幔不同粘滞性系数对地表形变和库仑应力变化的影响。计算结果显示，该地震是一个右旋走滑为主兼有一定逆冲性质的地震，其同震位移巨大，能量释放较彻底；同震破裂造成震中郯城县西北、东北和南部部分断层库仑应力增加，而震后形变使得这些断层库仑应力进一步增加，在单县、宿迁和日照等地，地震后350 a库仑应力变化量达到+1bar-+1MPa量级；地幔粘滞性系数不同，形变量和库仑应力变化达到稳定的时间不同，但最终趋于稳定的数值基本一致。

THE EFFECT OF 1668 TANCHENG M8.5 EARTHQUAKE ON THE SEISMIC ACTIVITY OF THE VICINITY FROM COSEISMIC AND POSTSEISMIC DEFORMATION

The Tanlu fault zone is an important active fault zone in east China. Many great earthquakes have occurred along it. The 1668 M8.5 Tancheng earthquake is the largest recorded event. With the constraint of surface rupture, we get a coseismic rupture model based on the elastic dislocation theory. In addition, we calculate the coseismic, postseismic deformation and Coulomb stress change of this earthquake with a viscoelastic multilayered model. The results show that the rupture fault of the earthquake is adextral strike-slip fault, which has slight thrust. The coseismic displacement of this event is very large. The accumulated energy is released thoroughly. The coseismic rupture of the 1668 Tancheng earthquake increased the Coulomb stress on the northwest, northeast and southeast faults of Tanlu fault zone. The Coulomb stress increases further due to the postseismic deformation. After 350 years of the Tancheng earthquake, the Coulomb stress changes in Shanxian, Suqian and Rizhaoget to +1bar-+1MPa. When the mantle is imposed different viscosities, the duration time which the deformation and Coulomb changes become stable will be different. However, the stable values of them are generally same.