A schema for the direct interpretation of electrical resistivity soundings

Abstract

A direct method for interpreting resistivity soundings acquired with any common electrode array has been developed. It is based on field resistivity transforms which are determined by the convolution of a linear filter with field apparent resistivity data. For a horizontally stratified earth model, the top layer is resolved in terms of its thickness and resistivity by means of two-layer curve matching and is then stripped off. Successive two-layer curve matching is applied to reduced field transforms until the whole section is uncovered. The quality of the interpretation is checked by computing model transforms by recursion for comparison with field transform data. Although designed for manual use the procedure can be semi-automated. Because the mechanics of the method highlight some important concepts in electrical geophysics the method has an educational role but it also has a place in the field situation whenever computers are unavailable.