Electromagnetic response of an infinite cable over a layered inhomogeneous earth with exponential variation of conductivity

Abstract

The problem of calculating the electromagnetic (em) field response of an infinite cable over an inhomogeneous earth is formulated for a multi-layer earth model with one of the layers having exponential variation of conductivity with depth. Solutions for the field components are obtained for the three-layer earth models with the intermediate layer possessing above conductivity variation. Computations are performed for the the absolute-amplitude ratio values, for the quasi-static approximations pertaining to geophysical applications. Results showing the effects of variation of transition layer thickness and conductivity contrast between the top and bottom layers are presented as a function of normalised distance (actual distance divided by the skin-depth computed using top layer conductivity). Results depict characteristic em response over inhomogeneous earth models.