Report on Nishinoshima (Japan) — 25 February-3 March 2015
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 25 February-3 March 2015
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2015. Report on Nishinoshima (Japan). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 25 February-3 March 2015. Smithsonian Institution and US Geological Survey.
27.247°N, 140.874°E; summit elev. 25 m
All times are local (unless otherwise noted)
According to news articles, the eruption at Nishinoshima continued at least through 27 February. The Japan Coast Guard noted that the island had grown to about 2.46 square kilometers and the active cone was about 100 m tall. Explosions occurred several times per minute and ash-and-gas plumes rose 1.2 km. Steam plumes rose from areas where lava flows contacted sea water.
Geologic Background. The small island of Nishinoshima was enlarged when several new islands coalesced during an eruption in 1973-74. Another eruption that began offshore in 2013 completely covered the previous exposed surface and enlarged the island again. Water discoloration has been observed on several occasions since. The island is the summit of a massive submarine volcano that has prominent satellitic peaks to the S, W, and NE. The summit of the southern cone rises to within 214 m of the sea surface 9 km SSE.