SYMMETRY PROPERTIES OF THE SURFACE IMPEDANCE TENSOR FOR STRUCTURES WITH A VERTICAL PLANE OF SYMMETRY

Abstract

For sites located in a vertical plane of reflection symmetry, the elements of the magnetotelluric impedance tensor Z satisfy a specific symmetry relationship in addition to the well‐known vanishing of the skew S: The diagonal tensor elements [Formula: see text] and [Formula: see text] both have the same argument α, invariant under rotation, as the sum [Formula: see text] of the off‐diagonal elements. Furthermore, it is shown that Z tensors exist which obviously do not satisfy the requirements of reflection symmetry, even though they yield S ≡ 0. The new condition adds a stringent requirement for consideration when one tries to assess from field data whether a structure does, or does not, possess a vertical plane of reflection symmetry; the condition should prove valuable especially because the solution of the inversion problem, which leads from Z(ω) to the conductivity structure σ(r), is generally not unique.