Fig. 4.

Maps showing the temporal change of the summit crater of Shinmoe-dake and the surrounding area. A: Before the 2011 eruption. The southern vents in the summit crater were used in the January 19 event. Distribution of vents including fissure vents of phreatic eruption in 1959 are after Geshi et al. (2010). B: On the morning of 28 January 2011. Within the crater, the open explosion vent (west side), the growing lava dome and the vent (east side) from which volcanic ash was continuously emitting. C: In the summer of 2012. The center of concentric pressure-ridges is emission point of lava, which locates near the center of the crater before the 2011 eruption. The surface of the lava dome, which grew during 28–31 January 2011, was broken by successive vulcanian events after 1 February 2011 and thickly covered by blocks and ash derived from the dome.