Development and application of 2D magnetotelluric inversion in complex domain

The magnetotelluric method is widely used in the investigation of the geo-electric structure of the earth. The field data are traditionally inverted to reveal the subsurface structure solved using regularised iterative inversion techniques. These interpretation schemes effect matrix computations in real domain due to operational simplicity. The speed of convergence of these techniques is controlled by the calculation type and the size of the program or more specifically, size of the matrices used. A common problem encountered when dealing with real matrices in 2D regularised inversion is their huge size. To partly overcome this problem, a new inversion strategy using complex singular value decomposition techniques has been successfully developed.;The use of analytical partial derivatives and a variety of problem regularization measures ensure that the scheme is stable and rapidly convergent. In this method, instead of using the Cagniard apparent resistivity and phase, the frequency normalised impedance is adopted as the interpretative data functions for improved model resolution. Sample applications to several synthetic and to field data from Parnaiba Basin in Brazil proved successful and are presented in this thesis. It is also found that the complex form of the data-space and parameter-space eigenvectors contain information on parameter resolution. Suggestions are made for further studies especially of methods of improving parameter resolution in 2D inversion.