大华北新构造运动和地震活动“成片迁移”的成因探讨

基于板块间的作用及有关物理参数,分别组构了大华北第Ⅲ（1484-1739年）、第Ⅳ（1815年至今）地震活动期的动力边界和厚度非均匀的“薄板”模型,采用有限元法,并根据地壳屈曲的研究,作了屈曲变形计算.所得屈曲图象与大华北新生代隆起、凹陷分布的基本特征一致,也与近30年来大华北垂直形变速率的分布特怔吻合.不同期高变形梯度区不同,7级以上地震均分布在这种区内.由此得出了新构造运动和地震“成片迁移”的力学机制.

THE CAUSE OF NEW TECTONIC MOVEMENT AND MIGRATION OF EARTHQUAKES IN GROUPS IN AND AROUND NORTH CHINA

On the basis of the interaction between the plates and of the physical parameters, we have construeted the dynamic boundary and non-homogenous thin plates models for the Third （1484-1739） and the Fourth （1815-） seismically active periods in and around north China. Using the finite element method and the research of crustal buckling, we have made the computation of buckling deformation. The results show that the buckling deformation is in accord with the basic 'character of distribution'of rise-sinking regions in Mesozoic era and with the character of vertical deformation in over thirty years in and around north China. The regions of high de-formatipn gradient are different in every period, and earthquakes of M≥7.0 were distributed in these regions. Using these results, ,we have discussed a mechanical mechanism for the new tectonic movement and the migration of earthquakes in groups in and around north China. This paper also presented a method to relate modern tectonic movement to the seismicity.