Fig. 3

Detailed configuration of the survey line and geological structure. The blue line represents the survey line along which the VPs and receivers were deployed. The green dashed and red dotted lines are the CMP lines set for processing the deep and shallow sections, respectively. The geological map and locations of lava domes reported by Hoshizumi et al. (2003) are also plotted. The hatched pattern indicates a geological feature as shown below the map. The triangles represent cones formed in the younger stage of Unzen activity. The red and yellow triangles show locations of the lava domes formed during the latest 1990–1995 eruption and during a past eruption, respectively. The black and white arrows denote the location of the vibration points for shot records in Fig. 5. The green rectangle denotes the area shown in Fig. 7.