2001年昆仑山口西Ms8．1地震前背景形变场的模拟研究

THE SIMULATION OF BACKGROUND CRUSTAL DEFORMATION FIELD OF THE M_S 8.1 KUNLUN EARTHQUAKE OF 2001

文中以东昆仑断裂带周围分布的27个GPS站点的地壳运动速率矢量为约束,利用半无限弹性空间三维断裂位错模型,反演了东昆仑断裂、柴达木盆地北缘断裂、玛尼-玉树断裂和玛尔盖茶卡断裂带在2001年昆仑山口西MS8.1地震之前的运动速率,并认为这些断裂带以反演出的运动速率错动所形成的形变场可以作为震前的背景地壳形变场。基于这一具有构造意义的背景速度场资料,计算了区域地壳应变率场和地震矩累积率场。结果表明,昆仑山口西地震前,东昆仑断裂的东西大滩段和玛尼-玉树断裂西段为该区域2个最显著的地震矩累积率高值区,其中东昆仑断裂的东西大滩段高值区为后来的昆仑山口西MS8.1地震的发震段。

Using the GPS velocity data of 27 stations around the East Kunlun Fault as restraints,we first inversed the slip rates of the eastern Kunlun Fault,the northern margin fault of Qaidam Basin,the Mani-Yushu Fault and the Maergaichaka Fault before the Ms 8.1 west Kunlun Mountains Pass earthquake with 3-D elastic half-space dislocation model. The deformation field calculated from these faults＇ slip movement can be considered as the background deformation field before the Ms 8. 1 Kunlun earthquake. Based on the tectonically meaningful data of the background deformation field,we calculated the strain field and seismic moment accumulation rate field. The results show that there are two obvi- ous regions of high moment accumulation rates,one is just in the Xidatan-Dongdatan segment of East Kunlun Fault where the Ms 8. 1 earthquake happened in 2001.