GPS约束下陇西地区断裂带现今滑动速率的非连续接触模拟研究

Research on Current Crustal Deformation in Longxi Area:Under the Constraints of GPS Results by Discontinuous Contact Model

以中国地壳运动观测网络1999、2001、2004和2007年4期GPS观测数据为边界条件,使用非连续接触有限元技术构建陇西块体二维有限元模型,在摩擦系数不确定性分析基础上,计算区内主要断裂带滑动速率。结果表明,现今地壳形变运动状态下陇西块体的北东向运动在海原断裂附近受到鄂尔多斯块体、阿拉善块体阻碍,陇西块体周缘的海原断裂带、老虎山断裂、西秦岭北缘断裂呈现左旋走滑特征,滑动速率为3.5mm/a、2.2mm/a和1.9mm/a,说明在青藏高原推挤作用下以上关键部位正在进行快速的构造应变积累。

Using GPS observation data of the 1999,2001,2004 and 2007 phases of the China crustal movement observation network,interpolation is applied to gain the boundary conditions of a 2-D element discontinuous model,which is used to simulate the slip rates of the fault system in Longxi area and undertake uncertainty analysis over it.The study determines that the NNE direction movement of Longxi block had been hindered by Orods and Alxa blocks.Haiyuan fault,Laohushan fault,and northern Xiqinling fault show a left-hand strike slip characteristic,and the slip rates are about 3.5 mm/a,2.2 mm/a and 1.9 mm/a respectively,which means that the tectonic stress has been accumulating in the key tectonic section rapidly.