Fig. 2

Vertical and horizontal cross-sections of the three‑dimensional (3-D) resistivity structure. a–c Vertical cross-sections of the study area in the N–S direction at EW =  − 250, 0, and 250 m, respectively. d–f Vertical cross-sections of the study area in the E–W direction at NS =  − 250, 0, and 250 m, respectively. The inverted white triangles indicate the audio-frequency magnetotelluric (AMT)/wideband magnetotelluric (WMT) measurement sites located within ± 50 m of each profile. See Fig. 1 for the profile locations and AMT/WMT sites. g–j Horizontal cross-sections of the study area at 1600, 1500, 1400, and 1200 m a.s.l. (above sea level), respectively. The symbols indicating the observation sites are the same as in Fig. 1b. k Spatial visualization of the resistivity structure beneath the active craters