基于GPS和水准资料的西秦岭北缘断裂现今闭锁程度分析

利用2009~2015年GPS速度场和1975~2011年垂直速度场数据，采用TDEFNODE负位错模型对西秦岭北缘断裂各段的闭锁程度、滑动亏损速率进行反演，结合GPS跨断层速度剖面和现今小震分布特征，对西秦岭北缘断裂各段的断裂活动性及地震危险性进行分析。结果表明，西秦岭北缘断裂以左旋走滑运动为主，兼有部分逆冲挤压，断裂各段的滑动速率都低于第四纪以来的滑动速率。其中天水-宝鸡段滑动速率较低，小震分布少，断裂正处于高应变积累阶段，具有高闭锁系数和滑动亏损速率，易于应变能的快速积累，具有发生中强地震的背景条件；锅麻滩段虽然滑动速率较大，但闭锁程度和滑动亏损速率高，小震分布较少，也存在较高的地震危险性；漳县段和鸳凤段滑动速率较大，断裂应力积累相对较弱，闭锁程度和滑动亏损速率均较低，小震分布多，地震危险性较低。

Analysis of the North Margin of West Qinling Fault Locking Based on GPS and Leveling Data

Using the GPS velocity field of 2009-2015, the vertical velocity field of 1975-2011, and the negative dislocation model of TDEFNODE, we invert for fault locking and fault slip deficit of the north margin of west Qinling fault. Using the GPS velocity profiles and distribution characteristics of small earthquakes, this paper analyzes the fault activity and seismic risk along different segments of the north margin of west Qinling fault. The results show that the characteristic of the whole fault is left strike slip with compression, the slip rate of each segment is lower than that of the quaternary period, the slip rate of Tianshui-Baoji segment is low, the faults have the lowest activity, the earthquake distribution of the fault is few, the faults have high locking fraction and high slip deficit rate, and they have the background conditions for the occurrence of moderately strong earthquakes. Although the slip rate of the Guomatan segment is high, the fault has high locking fraction and high slip deficit rate, earthquakes are fewer, and the seismic risk is high. The slip rate of the Zhangxian and Yuanfeng segments are higher, the faults have the highest activity, the earthquake distribution of fault is greater, they have low locking fraction and low slip deficit rate, and the seismic risk is low.