Fig. 2

Apparent resistivity and phase maps for the observed data (Obs.) and calculated responses (Cal.) from the best-fit resistivity model (Figs. 4, 5) for four frequencies (1.17, 6.9, 18.8 and 115 Hz). The responses shown here were calculated from the sum of the squared elements’ invariant impedances. See the text for more details. The dotted line indicates the caldera rim, and the shaded region marks the surface extent of Lake Ashinoko