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Report on Nikko (Japan) — December 1990


Bulletin of the Global Volcanism Network, vol. 15, no. 12 (December 1990)
Managing Editor: Lindsay McClelland.

Nikko (Japan) No water discoloration seen in 1990

Please cite this report as:

Global Volcanism Program, 1990. Report on Nikko (Japan) (McClelland, L., ed.). Bulletin of the Global Volcanism Network, 15:12. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199012-284132



23.078°N, 142.326°E; summit elev. -392 m

All times are local (unless otherwise noted)

No discolorations were observed at . . . Nikko . . . during 1990.

Geological Summary. Nikko submarine volcano is a massive seamount that rises from nearly 3 km depth to within 392 m of the ocean surface near the N end of the Mariana Volcanic Arc. Two large cones at the basaltic-to-andesitic volcano have been constructed on the NW and NE rims of a roughly 3-km-wide, flat-floored submarine caldera, whose rim is prominently displayed on the southern side, but largely buried on the north. A smaller cone is present on the SE caldera floor. The larger NW cone lies within a partially buried crater and displays hydrothermal activity. Discolored water was observed in July 1979, but none has been observed during semi-regular seasonal reconnaissance flights since then. Hydrothermal venting was documented during a NOAA expedition.

Information Contacts: Hydrographic Department, JMSA.