All resistivity measurements were highly repeatable and reproducible, characterised by an average standard deviation of 0.05 Ωm and a maximum of 0.28 Ωm, and thus all resistivity data were retained for inversion. The data were inverted using the DCIP2D algorithm (Oldenburg and Li, 1994; Li & Oldenburg, 2000) with a default Chi-factor to obtain smoothly varying 2D models of bulk resistivity.