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Inversion to Recover Electrode position Displacements on 3D Electrical Resistivity Tomography Monitoring Grids
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, Near Surface Geoscience 2014 - 20th European Meeting of Environmental and Engineering Geophysics, Sep 2014, Volume 2014, p.1 - 5
Abstract
Electrodes installed on active landslides and vulnerable earthworks to monitor changes in resistivity associated with moisture dynamics can be subject to movement. This affects the geoelectrical data and leads to errors in the resulting Electrical Resistivity Tomography (ERT) images. This paper demonstrates the selection of appropriate ERT measurements to provide sensitivity to electrode displacements in both directions on a plane. A combination of linear and equatorial dipole-dipole measurements are considered, which permit use on rectangular grids of any aspect ratio. A Gauss-Newton inversion scheme is developed that allows for the incorporation of constraints based on the magnitude and direction of movement. The effects of the constraints are demonstrated using synthetic data designed to simulate a planned laboratory experiment. In the presence of realistic levels of data noise and uncertainty in the preferred directions of movement, the inversion method is able to recover the displacements of the electrodes with a root-mean-square misfit of less than 1% of the electrode spacing.