北天山地区震源机制与构造应力场特征

本文利用新疆测震台网记录的宽频带波形数据, 采用CAP方法反演北天山地区2010—2018年M_S≥3.0地震震源机制解, 进一步结合早期研究区的震源机制数据反演了应力场。 结果表明, 研究区地震破裂类型以逆断型和走滑型为主, 其次为正断型, 过渡型最少; P轴方位大体与北天山地区主要断裂构造的走向垂直, 研究区以中部和西部近NS向以及东部近NNE向的水平挤压作用为主; 分区反演应力场显示研究区北部最大主应力轴σ₁方位由西到东呈NNW—NS—NNE渐变过程, 研究区南部最大主应力轴σ₁方位自西向东先呈NS—NNE变化, 再呈NNW—NS—NNE渐变; 研究区R值普遍较大, R值较小的区域主要位于研究区的西部和东部, 说明研究区东部和西部部分R值较小的地区向东西方向的扩展分量较小, 主要表现为物质的隆升分量。

The Focal Mechanism and Stress Field Inversion in Northern Tianshan Mountain

In this paper, based on the broadband waveform data recorded by Xinjiang Seismic Network, the focal mechanism of M_S≥3.0 earthquake from January 2010 to December 2018 are inverted by CAP method in northern Tianshan mountain. Combined with the focal mechanism data in the early stage, the stress field in the study area is inversed. The results show that the seismic rupture types are mainly thrust type and strike-slip type, followed by normal fault type, and the transition type is the least in the study area. The azimuth of P axis is generally perpendicular to the strike of the main fault structures in northern Tianshan mountain. The western and central region stress field is mainly under action of the level extrusion of NS, and the eastern region stress field is mainly under action of the level extrusion of NNE. The azimuths of the maximum principal compressive stress of the northern region stress field present the gradual process of NNW-NS-NNE from west to east, the azimuths of the maximum principal compressive stress of the southern region stress field present the process of NS-NNE-NNW-NS-NNE from west to east; The R value of the study area is generally large, and the areas with small R value are mainly located in the western and eastern of the study area. It indicates that the expansion component is small in the east and west direction, which is mainly manifested as the uplift component of the material.