利用反演方法确定新疆伽师地震的定位

PRECISE LOCATING OF JIASHI, XINJIANG EARTHQUAKE BY USING INVERSION METHOD

运用一种广义反演方法 ,在任意垂向非均匀介质中 ,根据近震P ,S波到时来确定地震事件空间位置的概率分布 ,应用此方法对新疆伽师地区临时数字地震台网的资料进行了定位处理 ,发现所定位的地震在平面图上呈明显的NNW向和NNE向线性分布 ,其中NNW向趋势略为明显。同时讨论了伽师地震的深部构造背景 ,对伽师地区天然地震的定位结果显示了地震与断裂的密切关联 ,该震群的形成与震源区附近的隐伏断裂有关 ,这可能是塔里木盆地北缘的地壳剧烈变形及现今构造运动所造成的结果 。

Jiashi region, Xinjiang is a strong earthquake area in western China. In recent years, several great earthquake swarms have occurred in this region, causing tremendous hazards. In order to get an insight into the relation between the deep structures and the generation of great earthquake swarm in this region, a generalized inversion technique for determining probability distributions of spatial locations of earthquake events through the travel times of P and S waves in random and vertically inhomogeneous medium, is used in this paper. Seismic data recorded by temporal digital seismic network deposed in this region were located using this method. The located earthquakes show linear distribution in north-northwest and north-northeast directions, among which the former is more distinct than the later. Based on the obtained results, the deep structural background of seismic activities in Jiashi region is discussed. The results indicate also the close relation between the earthquake and fault structures in Jiashi region. It is clear that the generation of earthquake swarm might be related to the buried fault in the vicinity of seismic source area, and might be the result of violent crustal deformation on the northern margin of Tarim basin and the present tectonic movement. These complicated structural framework and peculiar environmental conditions might be responsible for the development and generation of the strong earthquake swarm in Jiashi region.