TOWARDS HIGH-RESOLUTION IMAGING OF SUBSURFACE POLLUTION: AN INTRODUCTION TO THE MAGNETO-ELECTRICAL RESISTIVITY IMAGING TOOL (MERIT)

In order to obtain unique, high-resolution images of subsurface contaminant movement it is particularly promising to combine data resulting from application of several geophysical monitoring techniques. We propose the Magneto-Electrical Resistivity Imaging Tool (MERIQ as a suitable method that aims to combine traditional electrical resistivity tomography (ERT) and magnetometric resistivity (MMR). MERIT involves simultaneous measurement of both the electric and the magnetic field responses to injection of a low-frequency current into the ground using modern lock-in technology, While the feasibility of ERT imaging of subsurface pollution has been proven beyond doubt, MMR has almost exclusively been used by the mining industry, and suitable data inversion schemes are not readily available. In order to resolve this shortcoming, we present an algorithm that allows reconstruction of the subsurface bulk electrical conductivity distribution from surface magnetic field data. The solution is unique in two dimensions. Forward and inverse modelling experiments involving conceptual and synthetic data are described, proving the usefulness of the proposed framework for the inversion of MMR data.

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