Magnetotelluric Modelling: Towards a 4-D Inversion

Abstract

Recent work has shown the utility of magnetotellurics (MT) in monitoring dynamic processes, however current MT inversion schemes are not optimised for time-variant resistivity models. In this study we investigate if we can improve inversion results by introducing a time axis into the model space, creating time-lapse (4-D) models. We outline an inversion methodology which is altered from the existing Occam inversion to accommodate temporal changes. Our inversion incorporates only one spatial dimension, however the method is extensible to 2-D and 3-D spatial models. We assess the effectiveness of our method compared to existing time-invariant inversion by comparing inversions of synthetic MT data with the two techniques. Motivated by methods in other geoelectrical techniques, we also compare regularisation schemes and assess their suitability for use with MT data. Based on the results of the study, our work aims to help establish an inversion scheme for MT monitoring data.