云南地区主要断层运动模型的GPS数据反演

GPS DATA INVERSION OF KINEMATIC MODEL OF MAIN FAULTS IN YUNNAN

利用云南地区 1999～ 2 0 0 1年GPS观测结果 ,采用稳健 贝叶斯最小二乘算法与多断裂位错模型 ,分析研究了云南地区主要断层运动的定量模型。结果表明 :云南地区地壳水平运动明显受断裂活动的影响 ;断裂活动性质与构造地质结果一致 ;红河断裂带活动以北段为最 ,中段次之 ,南段最小 ;小江断裂带活动最强烈 ,其次为澜沧江断裂带、怒江断裂带北段 ,曲江断裂带显示出枢纽断层特征 ;各断层具有每年发生 6级左右地震的能力 ;较大的最大剪应变值主要分布在主要断裂带沿线及其交汇处 ;地震并非发生在最大剪应变值最大处 ,而大多发生在其高梯变带上 。

On the basis of GPS observations in Yunnan between 1999 and 2001, we adopt the robust Bayesian least square estimation and multi fault dislocation model to analyze the quantitative kinematics models of the main faults in Yunnan. The geodetic inversion suggests that: ①The horizontal movement of crust in Yunnan is affected distinctly by faults activity whose characters are consistent with geological results; ②The activity of the north segment of the Red River fault zone is maximum, in the middle segment is moderate, and in the south segment is minimum; ③Among others,the Xiaojiang fault zone has the stronggest activity, the secondary are the Lancang fault zone and the north segment of Nujiang fault zone, the Qujiang fault zone shows the characteristic of hinge fault; ④Each fault could produce an earthquake of \%M\%s=6 more or less per year; ⑤The larger value of maximum shear strain are mostly located along the main active fault zones and their intersections; earthquakes did not occur at the place of maximum shear strain, and mostly take place at the higher gradient zones, especially at its corner.