基于1999-2007年、2009—2013年两期中国大陆GPS水平速度场数据,使用DEFNODE负位错程序反演计算了汶川地震前后陇西块体周边断层——海原-祁连山断裂、六盘山断裂、庄浪河断裂和西秦岭北缘断裂的断层闭锁程度与滑动亏损动态空间分布,并讨论了汶川地震对块体周边断裂的影响和可能存在的强震危险段。结果表明,汶川地震后西秦岭北缘断裂中西段闭锁程度有所减弱、中东段闭锁程度有所增强,地震可能对其有一定影响;在汶川地震前后,其它断裂的断层闭锁程度没有发生明显改变,地震可能对其影响较弱。目前冷龙岭断裂、金强河断裂、庄浪河断裂、六盘山断裂、西秦岭北缘断裂中西段部分区域的闭锁程度较强,闭锁深度约为20-25km,结合地质尺度的断层地震空区等结果,分析认为上述断裂可能为地震危险段。汶川地震前后陇西块体周边平行断层滑动亏损速率中,除庄浪河断裂为右旋滑动亏损以外,其它断裂均为左旋滑动亏损;陇西块体周边垂直断层滑动亏损速率则均为挤压。
By using GPS horizontal velocity field data during 1999 -2007 and 2009 -2013 periods and the negative dislocation model of DEFNODE, we inverted the dynamic spatial distribution of fault locking and fault slip defi- cit in the faults around the Longxi Block before and after the Wenchuan earthquake, such as Haiyuan-Qilian Mountain Fault, Liupan Mountain Fault, Zhuanglang River Fault, and north fringe fault of west Qinling Moun- tain. Then we discussed the influence of Wenchuan earthquake on the faults and analyzed the seismic potential sections combining with seismic gaps and some other research. The results show that the Wenchuan earthquake possibly has some influence on the north fringe fault of west Qinling Mountain, because its middle-western seg- ment is locked weekly and its middle-eastern segment is locked tightly after the earthquake. The locking of the other faults are almost same before and after the Wenchuan earthquake, which means that the earthquake has little influence on these faults. At present, Lenglongling Fault, Jinqiang River Fault, Zhuanglang River Fault, Liupan Mountain Fault and middle-western segment of the north fringe fault of west Qinling Mountain are locked tightly and their locking depth is about 20 - 25 km. These faults are seismic potential segments considering seismic gaps along the faults in the geological scale. The parallel fault slip deficit in the faults around the Longxi Block are all sinistral strike-slip deficit except that the Zhuanglang River Fault is dextral strike-slip deficit before and after the Wenchuan earthquake, and the vertical fault slip deficit of the faults are all compression deficit.