郯庐断裂带中段(沂沭断裂带)电性结构研究与孕震环境

穿过郯庐断裂带中段（沂沭断裂带，36°N）所做的大地电磁测深（MT）剖面长约150km.使用Robust技术和远参考道大地电磁方法处理观测数据.通过分析视电阻率、阻抗相位、Swift二维偏离度和区域走向，定性确定测区的电性结构.二维反演解释中选择非线性共轭梯度（NLCG）方法，使用TE、TM两种模式资料联合反演，沿剖面的二维电性结构显示：自西向东，鲁西隆起、郯庐断裂带、胶莱坳陷及鲁东隆起4个电性区块分别对应，鲁东和鲁西隆起区为高阻，郯庐断裂带电性结构复杂，高、低阻相间，胶莱坳陷为低阻（高导）区.沿MT剖面附近曾发生3个地震，其震源区处在电性变化剧烈部位，并在震源区附近存在高导体.

Analysis of electric structure of the central Tan-Lu fault zone (Yi-Shu fault zone, 36°N ) and seismogenic condition

Magnetotelluric(MT) data along about 150km profile has been collected along the profile across the central Tan-Lu fault zone(Yi-Shu fault zone,36°N ).The observational data of this survey are processed by using the Robust method and remote reference technique. Apparent resistivity, impedance phase curves, Skewness and regional strike were anylysed. By means of the NLCG method,2D inversion modeling is performed with the data of two modes TE and TM. The 2D electrical structure along the profile is obtained. The target area can be divided into four electrical conductivity blocks, which separately correspond to the Lu-Xi uplift, Tan-Lu fault zone, Jiao-Lai depression, and Lu-Dong uplift. There is high resistivity in the uplift area of Lu-Xi and Lu-Dong and low resistivity in the depression of Jiao-Lai. The development and occurrence the earthquakes are closely related to the deep electric structure. The earthquake focus area of three earthquakes around the MT profile are significantly heterogeneous, and the high conductivity layer existed near the hypocenter region.