Fig. 1

Maps of the Nakadake and Nakadake first crater, Aso volcano. The right figure shows the location of the Aso volcano in southwest Japan, and the left figure shows the locations of representative post-caldera volcanoes (< 90 ka), except for Nakadake, which formed 150 ka. The dashed black line labeled A2 in the left figure indicates the profile used by Hata et al. (2016) to estimate the cross section of three-dimensional electrical resistivity