The application of impedance phase in long period magnetotelluric sounding

摘要

In the long period magnetotelluric sounding, the effect of random noise on the "dead band" frequency is very great. In this period band the whole apparent resistivity curve fall down, the deviation is relatively large, and is not good for the inversion fitting. In order to solve this problem, the standard approach to remove these effects is to use a magnetic remote reference. In cases where this is unavailable or does not work because noise is correlated at the local and remote sites, it is possible to extract unbiased estimates using an inversion algorithm that predicts the magnitude from the phase. Based on the theory that impedance phase is unaffected by random noise. This paper applied the theory to the post data processing of luqu-Songpan-Zhongjiang profile. Theoretical calculations and practical application results indicate that the distorted apparent resistivity can be recovered by the use of impedance phase.