Report on Kaitoku Seamount (Japan) — October 1984
Scientific Event Alert Network Bulletin, vol. 9, no. 10 (October 1984)
Managing Editor: Lindsay McClelland.
Kaitoku Seamount (Japan) Discolored water after 3 months of quiet
Please cite this report as:
Global Volcanism Program, 1984. Report on Kaitoku Seamount (Japan) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 9:10. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198410-284100
26.1217°N, 141.0955°E; summit elev. -95 m
All times are local (unless otherwise noted)
JMSA reconnaissance revealed few signs of activity since the March eruption. Pumice was observed only around the eruption site; none washed up on shore.
Activity gradually declined. To the crew that overflew the area at noon on 9 April, the water discoloration was barely distinguishable, and no ejecta or plume was seen (table 1). JMSA and JMSDF saw no discolored water or other activity on 10 and 31 July, 1 August, and 6 and 26 September. However, the crew of the MV Emblem reported a 3.5-5-km area of upwelling and water discoloration on 15 October.
|07 Mar 1984||9 x  km of discolored water|
|08 Mar 1984||Floating lapilli; 0.5-3 x 50 km of discolored water|
|09 Mar 1984||Seawater temperature at vent 0.5°C higher than floating lapilli; 9-13 x 30 km of discolored water|
|12 Mar 1984||Floating lapilli; discolored water|
|13 Mar 1984||Seawater near vent 0.5-1°C higher; floating lapilli; vapor plume|
|15 Mar 1984||Floating lapilli|
|16-19 Mar 1984||Floating lapilli; vapor plume|
|22 Mar 1984||Dark plume; luminescence at night|
|23 Mar 1984||Vapor plume; luminescence at night|
|24-25 Mar 1984||Vapor plume|
|26 Mar 1984||Floating lapilli|
|09 Apr 1984||0.3 x 5 km of very weak water discoloration|
|09-10 May 1984||Area of discolored water 0.3 km in diameter|
|15 May 1984||White upwelling and discoloration, 3.5 km in diameter|
|18 May 1984||Milky white discoloration, 0.18 km wide|
|09 Jun 1984||Weak green discoloration, 0.15 x 0.05 km|
Further Reference. Tsuchide, M., Kato, S., Uchida, A., Sato, H., Konishi, N., Osaka, J., and Hirabayashi, J., 1985, Submarine volcanic activity at the Kaitoku seamount in 1984: Rep. Hydrograph. Res., v. 20, p. 47-82.
Geological Summary. Submarine eruption have been observed during March 1984 and August 2022-January 2023 from Kaitoku Seamount (Kaitoku Kaizan), a three-peaked submarine volcano 80 km NNW of Kita-Ioto. The type of activity related to other observations of discolored water or bubbling, including an observation from 1543 CE, is uncertain.
Information Contacts: JMA, Tokyo.