用变形分析方法研究鲜水河断裂带的地震形变

RESEARCH ON EARTHQUAKE DEFORMATION ALONG XIANSHUIHE FAULT ZONE USING METHOD OF DEFORMATION ANALYSIS

提出了一种变形分析和用Ｒｏｂｕｓｔ原理进行位移场变换的方法，并用以计算了鲜水河断裂带的水平形变，给出了比较客观的位移场。按均匀应变模型计算了点和图形的均匀应变和分区应变的加权平均值，结果说明主应变轴方位与破裂线方位相关；在北西走向的主干断裂上，无论是破裂区或闭锁区，主压应变轴方位都是近东西向的。采用样条函数和截断多项式函数拟合跨断裂的点，用非线性动态平差模型求得了地震区的垂直形变模型，结果显示了道孚地震震前的加速形变、震时以震中为中心的下沉和震后的反向回升运动。

A method of deformation analysis is devcloped and the idea on transformation of displacement field is put forward based on the theory of Robust estimation.The horizontal deformation in Xianshuihe fault is computed using the software package developed on basis of the method and an objective displacement field is obtained. Even strain and weighted mean value of regional strain are calculated under even strain model,and the results show that the orientation of main strain axis is relative to that of rupture line,and along the principal fault of NW trend, the main strain axes in both rupture and locked region are all eastwestern orientation. Using spline function and step polynomial function to access the cross fault points and nonlinear dynamic adjustment model to obtain the vertical deformation model in earthquake area,the spatial and temporal veriations of vertical deformation on any point can be made out.And this interprets the coseismic subsiding and the reverse uplifting movement after quake during Daofu earthquake.