A comparison of the stability of stationary and non-stationary magnetotelluric analysis methods

Abstract

A Magnetotelluric (MT) sounding was carried out at a site in south‐east Queensland, in the Clarence‐Moreton Basin. The synoptic recordings were taken over a period of four months at sampling frequencies from 500 Hz to 5 × 10‐5 Hz. The resulting data was analysed by the stationary cross‐frequency and the Cone kernel time‐frequency distribution (TFD) methods of MT analysis. The results were compared as apparent resistivities on a daily basis for frequencies above 1 Hz, as well as over all the available data. The TFD MT apparent‐resistivity results were more stable and less noisy on an daily basis than the cross‐frequency results. Similarly the TFD analysis gave less noisy results than the cross‐frequency analysis when all available data was processed. Application of these new non‐stationary analysis techniques to MT processing should decrease the bias error problem of the MT methods and so increase reliability and repeatability of MT soundings.