The use of invariant impedances in magnetotelluric interpretation

Abstract

It is suggested that the use of ‘invariant’ impedances may avoid the possible erroneous interpretation of magnetotelluric data which can occur when 1‐D modelling of the E‐polarization response is carried out. The possibility of erroneous interpretation occurs in the vicinity of near‐surface 3‐D conductivity anomalies. The suggestion is tested on a numerical 3‐D model first published by Wannamaker et al. (1984). A correct interpretation of the conductivity structure is obtained. However, over a shallow highly‐conducting anomaly it is not possible to resolve deep structure. Copyright © 1988, Wiley Blackwell. All rights reserved