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Report on Minami-Hiyoshi (Japan) — May 1978


Scientific Event Alert Network Bulletin, vol. 3, no. 5 (May 1978)
Managing Editor: David Squires.

Minami-Hiyoshi (Japan) Green discolored water seen on 10 January

Please cite this report as:

Global Volcanism Program, 1978. Report on Minami-Hiyoshi (Japan) (Squires, D., ed.). Scientific Event Alert Network Bulletin, 3:5. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN197805-284131



23.5°N, 141.935°E; summit elev. -107 m

All times are local (unless otherwise noted)

Four areas of pale green discolored water were observed on 10 January. [JMA has added the information that JMSA flight crews on 10 and 24 January saw no discoloration, but it was seen on 26 January and again on both 23 February and 24 March by JMSDF aircraft personnel. As noted in the long tables above under Fukutoku-okanoba, discoloration was not seen on 13 April or on any subsequent flights.]

Geological Summary. Periodic water discoloration and water-spouting have been reported over this submarine volcano since 1975, when detonations and an explosion were also reported. It lies near the SE end of a coalescing chain of youthful seamounts, and is the only historically active vent. The reported depth of the summit of the trachyandesitic volcano has varied between 274 and 30 m. The morphologically youthful seamounts Kita-Hiyoshi and Naka-Hiyoshi lie to the NW, and Ko-Hiyoshi to the SE.

Information Contacts: JMA, Tokyo.