导体边缘附近虚感应矢量性质的数值模型研究

NUMERICAL INVESTIGATIONS ON THE BEHAVIOUR OF THE IMAGINARY INDUCTION ARROWS NEAR THE CONDUCTOR-HOST INTERFACE

本文用E极化的二维有限元法和有限差分法研究导体层边缘附近的虚感应矢量.首先,研究有一定埋深的导体——围岩界面处的情况,其中包括虚感应矢量的频率响应.其次,研究了海岸效应的虚感应矢量的频率响应.在海岸效应中不仅考虑了不同海水层厚度的影响,还考虑了海水与陆地的电导率比值大小对虚感应矢量的影响.最后,研究了被动陆缘(passive continental margin)处的海岸效应,检查磁感应矢量的测量是否能揭示海岸下面深部电导率的横向变化(即与岩石层厚度变化有关联的电导率变化).

The finite element method and the finite difference method are used for studying the behaviour of the imaginary induction arrows near the conductor-host interface in the E-polari-zation case. Firstly, we calculate the frequency response of the induction arrows of a buried conductor, model. Secondly, we study the ocean-coast effect (when the buried depth of the conductive layer is zero) by investigating the influence of the thickness of the ocean to the behaviour of the imaginary induction arrows. Furthermore, we carry out research on the influ ence of the sea-land conductivity contrast to the ocean-coast effect. Lastly, we investigate the ocean-coast effect at a passive continental margin in order to examine whether the measurement of the geomagnetic induction arrows can reveal a lateral variation of the deeply embedded conductivity structure, which is related to the changing lithospheric thickness.