COHERENCE FUNCTIONS FOR MAGNETOTELLURIC ANALYSIS

Abstract

A multiinput linear system approach is used to study the magnetotelluric phenomena in the presence of lateral conductivity inhomogeneities in the earth. The three types of coherence functions (ordinary, multiple, and partial) are defined, and their use in magnetotelluric data analysis is illustrated with a field example. Partial coherence functions are used to determine the principal axes in the case of two‐dimensional type inhomogeneities, and as measures of three‐dimensionality in the case of non‐two‐dimensional type structures. The results obtained using coherence functions are compared with those obtained with the conventional tensor impedance method.