Fig. 3

Oblique aerial photographs of the crater and lahar deposits taken after the September 2014 eruption. a View of the entire area of the Nigorisawa River through which the syneruptive-spouted type lahar flowed. b One wall of the Jigokudani crater. The red arrows indicate a gutter of water. c The new crater, which formed on the western flank of Mount Ontake. The yellow arrow indicates hot water that overflowed from the crater. The red arrow indicates the tongue-shaped lahar deposit. d Deposit from the pyroclastic density current that flowed down the south side of the volcano. Running water eroded deposits in the vicinity of the Shirakawa River (red arrow), although the running water was clear. In the Akagawa River, a syneruptive-spouted type lahar was deposited at the bottom of the gorge. e View of the confluence of the Akagawa and Shirakawa Rivers. The syneruptive-spouted type lahar overflowed to the location indicated by the red arrow (site C). Muddy water flowed downstream (yellow arrow). Reworked deposits of the pyroclastic density current were not present at a check dam (blue arrow) of the Shirakawa River. f View of the confluence of the Nigorigawa and Denjogawa Rivers. The red arrow indicates site D. The syneruptive-spouted type lahar had not arrived at site D by the time this photograph was captured, although a lahar did arrive at this location later because of heavy rain