3-D Natural Electromagnetic Field Source Geo-Electromagnetic Response Study

Correlation analysis and imaging properties research for 3-D magnetotelluric numerical simulation results of complex subsurface medium is applied, the results of which are helpful for multi-dimensional magnetotelluric data processing, the selection of inversion objective function, and information interpretation. Different apparent resistivity and phase definition on the base of different kinds of rotation invariants were used together with correlation analysis and imaging research, meanwhile we have selected 6 response values on the base of different rotation invariants, which are Re_det(Z), Im_det(Z), det(Z), detRe(Z), detlm(Z), and phase. In all, by a lot of synthetic model field model simulation experiments, we derived that the correlation and imaging analysis between responses based on different rotation invariants and subsurface electrical property structure are feasible, on some scales correlation curves are connected essentially with subsurface electrical property structure, even in the cases of shallow depth existed 3-D anomaly and 3-D depth structure; Re_det(Z)-based apparent resistivity definition is closer to the phase change than other definitions from viewpoint of correlation curve; Sudden changes accompanying with keyhole exists around the site keyhole occurs; And high-contrast imaging convert in a very narrow period range. Naturally some questions existed, for example the physical principle of keyhole,noise influence, and so on.