The solution of the one-dimensional inverse problem for induction soundings by an efficient linearization technique

A non-parametric method, the efficient linearization technique (ELT), is proposed for the inversion of induction soundings for a spherical Earth model with a radial conductivity distribution. The method is based on the fact that when linearizing the operator of the direct problem, the quantitative estimate of its non-linear term is taken into account, which makes the solution search procedure stable. At each iteration stage, the conductivity function correction is sought in the region where linearization is admissible. ELT makes it possible to evaluate the resolving power of the data and also the confidence interval for the conductivity function. Model examples illustrate the features of this method. The results of interpretation of magnetotelluric data are compared with nearby drill hole resistivity logs. A model of the conductivity distribution in the mantle based on global magnetovariational data available up to 1986, is constructed. This model is consistent with modern knowledge of physical processes occurring in the interior of the Earth.