1976年唐山地震震时和震后变形的模拟

本文采用三维粘弹性有限元方法拟合唐山地区１９７６-１９８５年观测到的地震震时和震后的水平与垂直地形变，反演华北板块下方深部物质的流变学性质．模型采用多层弹性覆盖层与线性粘弹性层的有限块体，发展断层面上存在着位错运动，并用正交设计法拟合观测数据．模拟计算表明，华北板块下方软流层粘度为７．１×１０^１８Ｐａ·ｓ；上地幔粘度为２．１×１０^１９Ｐａ·ｓ．

THE SIMULATION OF COSEISMIC AND POSTSEISMIC CRUSTAL DEFORMATION DUE TO TANGSHAN EARTHQUAKE IN 1976

In this paper, the observed coseismic and postseismic deformation due to Tangshan earthquake was fitted by inversional computation.Both the horizontal and vertical postseismic deformation fields（1976-1985） after Tangshan earthquake（1976,Ms7.8） are simulated by means of a 3-dimensional finite element method for viscoelastic medium.A model of the deep structure of North China plate with a dislocation on the Tangshan earthquake fault is used. The fault is located in a multilayer elastic medium（lithosphere） lying over a liner viscoelastic layer（asthenosphere）,To direct the inversional computation, the orthogonal design method is applied.From the coseismic and postseismic crustal deformation, the inversional computation suggests an asthenospheric viscosity of 7.1×10¹⁸Pa·s and a viscosity of 2.1×10¹⁹Pa·s for the upper mantle underlying the continental lithosphere.