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
Kaitoku Seamount
Japan
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.
Table 1. JMSA observations at Kaitoku Seamount, March-June 1984. Courtesy of JMA.
| Date | Observation |
| 07 Mar 1984 | 9 x [28] 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.
