Report on Nishinoshima (Japan) — 19 July-25 July 2017
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
19 July-25 July 2017
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2017. Report on Nishinoshima (Japan). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 19 July-25 July 2017. Smithsonian Institution and US Geological Survey.
27.247°N, 140.874°E; summit elev. 25 m
All times are local (unless otherwise noted)
The Japan Coast Guard reported that visual observations of Nishinoshima from an aircraft during the afternoon of 11 July confirmed that the eruption was ongoing. Emissions from the center of the cone were grayish white and tephra was ejected. The lava flow on the W flank continued to enter the ocean. Based on a pilot observation the Tokyo VAAC reported that on 18 July an ash plume rose to 3 km (10,000 ft) a.s.l.
Geological Summary. 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.