(a)–(e) 8 km depth slices for the resistivity models in Table 1. (a) Resistivities of all the mesh elements within the 10 Ω·m iso-surface in Fig. 10 set to 1 Ω·m. (b) Element resistivities within the 5 Ω·m iso-surface set to 1 Ω·m. (c) Corresponding depth slice through the preferred inversion model. (d) and (e) Element resistivities within the 10 and 20 Ω·m iso-surfaces set to 10 and 20 Ω·m, respectively. (f) Corresponding yx apparent resistivity and impedance-phase curves for these models (different colours) at the locations shown by the white dots in (a)–(e).