Hydrogeophysics, Electrical resistivity tomography (ERT), Inverse theory, Tomography 1 INTRODUCTIONĮlectrical resistivity tomography (ERT) is a geophysical method where current is injected between pairs of electrodes attached to the surface of the earth while the voltage differences are measured between other electrode pairs. On large finite element meshes, the calculation time of the newly developed approach was also proven to be orders of magnitude faster than the 3-D adjoint method and addressed modelling errors in the 2-D perturbation and adjoint electrode position Jacobian. A new 2.5-D formulation for the electrode position Jacobian is developed and is shown to give accurate numerical solutions when compared to the adjoint method on 3-D models.
Results show fewer resistivity artefacts and suggest that electrode movement and resistivity can be reconstructed at the same time under certain conditions. We apply this to ERT monitoring data from an active slow-moving landslide in the UK. In this work, we demonstrate a joint resistivity and electrode movement reconstruction algorithm within an iterative Gauss–Newton framework. But movement of electrodes or incorrect placement of electrodes with respect to an assumed model can introduce significant resistivity artefacts into the reconstruction. Electrical resistivity tomography (ERT) is increasingly being used to investigate unstable slopes and monitor the hydrogeological processes within.
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