ＭＴ法電磁探査における三次元解析技術の検討

Abstract

A quasi-linear inversion method is a new algorithm for the 3D MT inversion that is going to stand the practical use in near future. The performance of this inversion method is quite high to realize the much shorter processing time than the conventional MT inversion method. In this paper, we have tested the quasi-linear inversion method by means of the numerical simulation. We applied the new inversion technique to the synthetic MT responses to the numerical models, and the input models were reconstructed successfully. We also applied the method to the real field data acquired in Minami-Noshiro area in Akita prefecture. The major geological features in this area are N-S trending structures of anticlines, synclines and faults. The 3D inversion results were consistent with the geological information. To visualize the highly complicated 3D structures of this area, the bird's-eye view was presented for the resistivity boundary at the Onnagawa formation top that was determined from the induction logging data. The geological structures of Nakazawa syncline, Sotooka anticline and the structural high of Minami-Noshiro oil field were clearly seen on the bird's-eye view. The major structure of the Noshiro thrust faults was also recognized in the western part of the bird's-eye view.