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Report on Kaitoku Seamount (Japan) — October 1984

Kaitoku Seamount

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


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.