Two-dimensional Magnetotelluric Regularization Inversion Jointed with TE- and TM-mode Data

The magnetotelluric inverse problem is ill-posed and the inverse results are unstable and non-unique. It means that different geo-electrical model could fit the observed data with the same accuracy. A stable solution of the ill-posed inverse problem can be obtained by utilizing the regularization methods in the objective function. Solving large scale linear equation of inverse problem, the damped Gauss-Newton algorithm was adopted, which can improve local convergence of Gauss-Newton method. On the one hand, inversion of TE-mode data is more sensitive for the low abnormal body and has poor resolution for the high abnormal body. On the other hand, inversion of TM-mode data has better resolution for the high abnormal body. Jointed two-mode data inversion is able to achieve better model and stack quality in considerably fewer iterations. In order to better inversion results, TE- and TM-mode magnetotelluric data are jointed. Through the synthetic model simulation, the inversion results truly reflected the geo-electrical parameters of the model and accurately showed the depth and size of the abnormal body.