Interpretation of the magnetotelluric impedance tensor: regional induction and local telluric distortion.

Abstract

A method for the interpretation of the magnetotelluric (MT) impedance tensor, the telluric-vector technique, is presented. The phase information of all impedance tensor elements is used to distinguish between local telluric distortion and regional induction. A model incorporating a superposition of the effects of local surface anomalies and a regional 1-D, 2-D or 3-D conductivity distribution is applied. In 2-D regional structures, a complete separation of the contributions of local and regional anomalies is possible if additional information from geomagnetic depth sounding (GDS) is used. A new skewness parameter derived from phases alone is introduced to measure the 3 dimensionality of the regional structure independent of local distortions.-AuthorInst fur Geophys der Univ Gottingen, Postfach 2341, D-3400 Gottingen, FRG.