Investigation of 2-D Electrically Anisotropic Structures Employing Magnetotelluric Data

Investigations made in current study illustrate that an application of 2-D isotropic inversion algorithm for magnetotelluric data affected by anisotropy could recover macro-anisotropy reasonably well. First anisotropy effects on common MT interpretation steps, dimensionality analysis and 2-D inversion modeling, are investigated. Two kinds of azimuthally anisotropic features (anisotropic block and anisotropic layer) which generally form a part of 2-D models are considered. The influence of different anisotropy strikes and resistivity contrasts on dimensionality analysis and on the behavior of induction arrows is studied. These investigations evince that, a strike direction close to the anisotropy strike can be chosen by the dimensionality analysis of the data. Then if the data are rotated to this angle, 2-D inversion would recover the anisotropy sensibly by means of macro-anisotropy. This procedure is tested successfully on a field data set where anisotropy had been previously recognized. The results show that the proposed approach reproduces the anisotropy acceptably via macro-anisotropy in the final inversion model.