Report on Nishinoshima (Japan) — 11 August-17 August 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
11 August-17 August 2021
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2021. Report on Nishinoshima (Japan). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 11 August-17 August 2021. Smithsonian Institution and US Geological Survey.
27.247°N, 140.874°E; summit elev. 25 m
All times are local (unless otherwise noted)
JMA reported that ash plumes from Nishinoshima were visible in satellite images on 14 August rising about 1.9 km and drifting N. The Japan Coast Guard conducted an overflight the next day and did not observe eruptive activity or new deposits from the day before. The Tokyo VAAC noted that a period of continuous ash emissions was visible in satellite data on 15 August.
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.