青藏活动地块区运动与变形特征的数值模拟

NUMERICAL SIMULATION OF MOVEMENT AND DEFORMATION OF QINGHAI-TIBET PLATEAU

利用二维有限元模型,以GPS测量的构造运动为约束条件,探讨了青藏活动地块在弹性应变积累过程中的运动与变形状态。模拟结果表明,青藏活动地块区在整体运动过程中,内部变形以大范围的分布为特征,其内部的应变分布和弹性应变能积累速率表明了Ⅱ级活动地块与活动边界带的显著变形差别活动地块内部的应变和弹性应变能积累速率相对较小且分布较均匀;活动边界带上变形相对集中,应变和弹性应变能积累速率相对较高,并呈非均匀分布。这反映了青藏地块区内所含的各Ⅱ级活动地块的运动变形的整体性特征及彼此间的差异性特征,也揭示了活动地块构造通过边界带变形等方式对大陆强震的控制作用。

We use 2-D elastic finite element model to explore the crustal movement and deformation in the process of strain energy accumulating of the Qinghai-Tibet plateau, taking the GPS surveying results from 1999 to 2001 as the constraining conditions. The simulation results show that the strain and energy distribution are different between inside the blocks and in the boundary zones of this plateau. The deformation and energy accumulation within block region are relatively small and their distributions are uniform, while the deformation and energy accumulation in active boundary zones are larger and their distribution are nonuniform relatively. This characteristic reflects the global characteristics of movement and deformation on the whole Qinghai-Tibet plateau and the different characteristics among its sub-blocks. It also illuminates the domination of strong earthquakes under the active block tectonic through the deformation of active boundary zones.