Report on Fukutoku-Oka-no-Ba (Japan) — June 1986
Scientific Event Alert Network Bulletin, vol. 11, no. 6 (June 1986)
Managing Editor: Lindsay McClelland.
Fukutoku-Oka-no-Ba (Japan) Discolored sea water
Please cite this report as:
Global Volcanism Program, 1986. Report on Fukutoku-Oka-no-Ba (Japan) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 11:6. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198606-284130.
24.285°N, 141.481°E; summit elev. -29 m
All times are local (unless otherwise noted)
Airplane pilots have observed discolored water at the volcano during all overflights after the temporary island was eroded below sea level in late March. No eruptive activity was reported. The length of the zone of discolored sea water was 0.3 km on 16 April, 2 km on 19 May, and 25 km on 18 June.
Geologic Background. Fukutoku-Oka-no-ba is a submarine volcano located 5 km NE of the pyramidal island of Minami-Ioto. Water discoloration is frequently observed from the volcano, and several ephemeral islands have formed in the 20th century. The first of these formed Shin-Ioto ("New Sulfur Island") in 1904, and the most recent island was formed in 1986. The volcano is part of an elongated edifice with two major topographic highs trending NNW-SSE, and is a trachyandesitic volcano geochemically similar to Ioto.
Information Contacts: JMA; JMSA.