川滇菱形块体主要边界运动模型的GPS数据反演分析

GPS INVERSION OF KINEMATIC MODEL OF THE MAIN BOUNDARIES OF THE RHOMBUS BLOCK IN SICHUAN AND YUNNAN

利用川滇地区 1 991— 1 999年的高精度GPS观测处理结果 ,采用稳健 -贝叶斯最小二乘算法与多断裂位错模型 ,分析研究了川滇菱形块体主要边界运动的定量模型 .反演分析表明 :川西鲜水河断裂带和安宁河断裂带的左旋走滑运动速率约 30mm a ,倾滑运动 (逆断层 )速率分别约 9— 1 1mm a ;滇西红河断裂带、程海断裂带、鹤庆-洱源断裂带的走滑运动 (分别为右旋、左旋、左旋 )速率分别约 1 0、1 1、1 3mm a,倾滑运动 (正断层 )速率分别约 1 6、2 4、1 6mm a;如将其视为弹性应力应变积累 ,则各断层每年有相当于 6级左右的地震能量积累 .依据上述反演结果 ,模拟了区域主要断层运动引起的水平位移、应变速率场图像 。

Based on GPS observation between 1991 and 1999 in Sichuan and Yunnan, we apply the robust Baye's least squares estimation and multi fault dislocation models to analyze the kinematic models of the main boundaries of the rhombus block in Sichuan and Yunnan. The geodetic inversion suggests that the left lateral strike slip rates of the Xianshuihe fault zone and the Anninghe fault zone in Sichuan are about 30 mm/a with overthrust faulting at rates of roughly 9 and 11 mm/a, respectively; in Yunnan, the right lateral strike slip rate of the Red River (Honghe) fault zone is 10 mm/a with a normal faulting of 16 mm/a; and the left lateral strike slip rates of the Chenghai fault zone and the Heqing-Eryuan fault zone are about 11 and 13 mm/a with the normal faulting at rates of about 24 and 16 mm/a, respectively. If all displacements along these faults were accommodated by elastic stress and strain, the accumulated seismic energy each fault would be sufficient to produce a moderate earthquake with M S～6 each year. According to above results, the horizontal displacement and strain field caused by the main fault movement have simulated and showed the interactions among boundary faults.