11. The Interpretation Model

Excerpt

Interpretation of the magnetotelluric and magnetovariational data starts with constructing an interpretation model. It is composed on the basis of a priory geological and geophysical information and plausible hypotheses. And great consideration is given to the analysis of magnetotelluric and magnetovariational response functions and their rough tentative inversions. Summing up different evidences (lithologic, petrophysical, tectonic, geodynamic, seismic, geothermic, geoelectric), we create reasonable qualitative image of the medium under consideration and constrain a model class, within which the solution of the inverse problem is sought for. The interpretation model should take into account the aim and the area of the search, that is, designate the target objects, which we are going to find, and characterize (at least presumably) the host medium, in which these objects are to be found. Just at this stage of interpretation we form the correctness set (a set of geophysically meaningful solutions) and transform the ill-posed unstable inverse problem into a conditionally well-posed stable one. Just at this stage of interpretation we compose an optimal grid for the inversion of field data, choose the normal background and starting values of resistivities (conductivities), suggest the strategy of solution of the inverse problem. …