The sensitivity analysis of different induced polarization models used in magnetotelluric method

Abstract

The magnetotelluric signal is a comprehensive response composed of electromagnetic induction and induced polarization (“IP effect”). The extracting of the IP response from MT signal is not only beneficial for improving the accuracy of MT exploration, but also the acquired IP effect can provide us with unique information about underground structure. There are many models proposed through laboratory measurements by some researchers to approximately describe the IP effect, and yet which model is comparatively proper and effective for the use in MT method is still unknown. Besides, due to the weakness of the induced polarization effect, it is a tough question when separating one from another in practical exploration. The main objective of this paper is to choose an IP model that is best suited for the manipulation in MT forward and inversion by calculating and analyzing the sensitivity and integrated sensitivity of apparent resistivity to the different IP model parameters. The analysis of these results offers some useful suggestions when selecting the IP model in MT method, and meanwhile the application range of IP method is expanded.