Fig. 13

Images of the eruption center and migration of the active crater during the 2015 eruption. Photographs were taken by a time-lapse camera (HSRI) and webcam (JMA). Locations of the cameras are shown in Fig. 2. a Area just before the 2015 eruption (darkened blending of images to erase steam). b First shot of active crater. A large crater (15-9) and intensive fumaroles (15-2, 15-3 and 15-4) are identified. c 15-6 and 15-9 seem to be connecting. d 15-6 crater itself was not observed from observation points; however, intensive steam in the photograph and geomorphological analysis after the eruption infers its existence. e The first shot of 15-5. Although 15-9 appears to be still active, the newly formed 15-5 seems more vigorous. 15-6 seems inactive. f It is evident that 15-5 had formed before 15-9 (c.f. photograph b). g The last shot of active 15-5. h The first shot of 15-1. The activity of 15-5 is not evident. i The first clear photograph taken after the eruption. Locations of extinct craters (15-5, 15-6 and 15-9) are also shown