1. Institute of Geophysical and Geochemical Exploration, CAGS, Langfang 065000, China;
2. Key Laboratory of Electromagnetic Detection Technology of Ministry of Land and Resources, Langfang 065000, China
A simple three-dimensional model, a low-resistivity abnormal body and a high resistance abnormal body located in one-dimensional layered medium were designed in this paper. The authors used the "+" and "*" type observation profiles as the analog form to carry out the comparative experimental study of the effectiveness of MT 1D, 2D, 3D inversion. The authors employed adaptive regularization (ARIA) to perform 1D inversion, and adopted nonlinear conjugate gradient (NLCG) to conduct 2D inversion and REBOCC to carry out 3D inversion. The comparison of the different inversion results below the profile with the original model shows that 1D and 2D inversion can be reflected in the results of real model information, while 3D inversion of REBOCC tends to build a three-dimensional model of macroscopic electrical characteristics. In the 1D inversion results, as for the deep electrical structure, the inversion result shows that the TE polarization mode is better than TM polarization mode, and the combination mode of TE and TM has a medium result between the TE and TM. In the 2D inversion results, usually the TM polarization mode is better than TE polarization mode, and the inversion results of combination mode of TE with TM are almost equal with the TM polarization mode inversion results, or even better. In the 3D REBOCC inversion results, due to the influence of multiple solutions on inversion results, the 3D inversion of REBOCC tends to build a three-dimensional model of macroscopic electrical characteristics.
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