大地电磁感应的场源效应

本文对大地电磁感应的场源效应进行了较详细的研究.用线电流为场源,均匀大地和三层结构为构造模型进行了计算,其结果与均匀场源的感应作了对比.场源效应受场源高度、信号周期、电阻率、测点距离等的影响.为了能更深入的了解和控制这影响,本文提出了“阻抗平均法”,该方法对消减场源效应有一定作用,使平面波的解释继续有效.

LINE SOURCE EFFECTS ON MAGNETOTELLURIC RESPONSES

Line source effects on magnetotellurics (MT) is studied in some detail. Models of a uniform earth and of a 3-layer structure with a line current source are used for the studies. The results are calculated and compared with those obtained assuming a uniform inducing field. Source effects vary with field periods, resistivity, source altitude and observation location. An impedance-averaging' technique is also studied in connection with line source effects. This average diminishes source effects and extends the validity of the plane wave interpretation.