Response of a multilayered earth with layers having exponentially varying resistivities

The resistivity kernel function for calculating the apparent resistivity of a multilayered earth with layers that have exponentially varying resistivities is derived using a recurrence relation. This relation is applicable to general cases in which layers have either constant or exponentially varying resistivities. A FORTRAN subroutine that computes the apparent resistivity of Schlumberger, Wenner, and pole‐to‐pole array soundings for layers of exponentially varying resistivities is presented. Apparent resistivities of some models computed by the new kernel function are compared with those of the same models approximated by a number of constant resistivity layers. Apparent resistivities computed by both methods show excellent agreement.