新疆玛纳斯大震区地壳深部的电性结构

ELECTRIC STRUCTURE OF THE CRUST OF THE MANAS EARTHQUAKE AREA IN XINJINAG AUTONOMOUS REGION

对玛纳斯大震区新近观测的大地电磁测深数据进行了处理，得到视电阻率曲线、阻抗相位曲线、二维偏离度、主轴方位角和地磁实感应矢量。然后对所有测点的资料进行了二维自动反演解释。结果表明，沿剖面的地壳浅部可划分为５个区段，沿剖面的深部可划分为３个区段，各区段的接触边界由断层或深断裂带组成。沿测线沉积盖层最大深度达１２ｋｍ左右；测线南段存在壳内低阻体。这些解释结果与地质及其它资料吻合较好。玛纳斯７．７级地震发生在地壳电性结构发生明显变化的接触带附近。

Magnetotelluric data have recently been obtained at 35 sites along a profile of about 93km long and orientated approximately N-S in the Manas earthquake area which lies in northern Tianshan mountains of Xinjiang Autonomous region From these data the apparent resistivities,impedance phases,skewnesses,optimal rotation angles and induction vectors were calculated and analysed The 2 D inversion method RRI was used for the data interpretation The results show that the shallow crust can be divided into 5 sections and the deeper crust into 3 sections according the electric structure The boundaries of different sections are coincidence with faults The maximum sediment basement is about 12 km deep The resistivity distribution near the Manas earthquake focal area is significantly heterogeneous