Geophysical Prospecting zyxwvuts 37,209-221, 1989 zyxwv MATRIX METHOD FOR THE TRANSFORMATION OF RESISTIVITY SOUNDING DATA OF ONE ELECTRODE CONFIGURATION TO THAT OF ANOTHER C 0 NFI GUR ATION' SRI NIWAS and M. ISRAIL2 ABSTRACT SRI NIWAS and ISRAIL, M. 1989. Matrix method for the transformation of resistivity sounding data of one electrode configuration to that of another configuration. Geophysical Prospecting Matrix equations are derived to transform the resistivity sounding data obtained in one type of a four-electrode array to the corresponding resistivity sounding data that would be obtained using a different four-electrode array. These expressions are based primarily on recent work in which we have established a linear relation between the apparent resistivity and the kernel function by using a powerful exponential approximation for the kernel func- tion. It is shown that the resistivity sounding data of two different four-electrode arrays have a linear relation through an essentially non-singular matrix operator and, as such, one is derivable from the other for a one-dimensional model and it can also be extended to two- dimensions. Some numerical examples considering synthetic data are presented which demonstrates the efficiency of the method in such transformations. Two published field examples are also considered for transformation giving a reliable interpretation. 37,209-221. INTRODUCTION At present one-dimensional (1D) resistivity computations for geoelectrical data intepretation are performed using digital linear filters (Koefoed zyx 1979). These are developed separately for three aspects of the computations: (1) estimation of the apparent resistivity function from the resistivity transform function; (2) estimation of the resistivity transform function from the apparent resistivity function; and (3) transformation of the apparent resistivity functions of one electrode configuration to that of another configuration. Received October 1987, revision accepted July 1988. Department of Earth Sciences, University of Roorkee, Roorkee 247 667, India. 209