Integration of magnetotelluric and seismic data analysis for delineating geological structures

Abstract

Integration of interpretation of two magnetotelluric and seismic results can enhance the Earth's image by leveraging their distinct geophysical properties, namely, resistivity and reflectivity, respectively. High similarity between different geophysical results in the collocated magnetotelluric and seismic profiles can highlight key geological features and mitigate non-uniqueness issues. We applied 2D and 3D inversion approaches to the magnetotelluric data. This process produces a range of possible resistivity scenarios that yield model responses closely matching the field data. Prior to the 2D magnetotelluric inversion, strike analysis was employed to generate a collection of datasets, including the original measurements and versions rotated by different strike angles. In contrast, 3D magnetotelluric inversion utilized the original data directly, without the need for the strike analysis. To evaluate the performance of these inversion approaches in 2D MT profiles, we compare their inverted resistivity results from 3D synthetic magnetotelluric data to the known 3D resistivity model. For seismic data analysis, we incorporate seismic textural attributes as energy, entropy and their k-means clusters to delineate layering and fault structures. To research the geology of Olympic Dam, Australia, we used the workflow that integrated the individual inversion of the real magnetotelluric and seismic datasets to provide spatial distribution of the resistivity, seismic layers, and faults. Boundaries of the resistive blocks and conductive zones match well with the 2D seismic horizons and faults interpreted by the seismic attributes, respectively. The consistency of the electromagnetic inversion results with the seismic data highlights the potential of this workflow in successfully detecting layers, major faults, and the deep Moho interface, confirming its effectiveness.