A method for calculating mise-à-la-masse anomalies in the case of high conductivity contrast by the integral equation technique

Abstract

The present paper describes a method for calculating mise-à-la-masse anomalies based on the assumption that each conducting body of the model is at its own constant potential. The fundamental constraint is that the conductivity of the conducting bodies should be at least one hundred times that of the environment. The problem is formulated by means of Fredholm's integral equation of the 1st kind developed for the potential. The integral equation is solved by the method of subareas, in which the boundary of the conductors is subdivided into subareas so small that the normal component of the current density on them can be taken as constant. In the numerical applications a comparison is made between the mise-à-la-masse anomalies of a truncated long cylinder, omitting the end effects and a complete 3-D model with the same shape. Factors affecting the shape and intensity of the anomalies are also considered with the aid of the long cylinder model.