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Report on Fukutoku-Oka-no-Ba (Japan) — January 1996

Bulletin of the Global Volcanism Network, vol. 21, no. 1 (January 1996)
Managing Editor: Richard Wunderman.

Fukutoku-Oka-no-Ba (Japan) Discolored seawater observed for the second time in three months

Please cite this report as:

Global Volcanism Program, 1996. Report on Fukutoku-Oka-no-Ba (Japan). In: Wunderman, R. (ed.), Bulletin of the Global Volcanism Network, 21:1. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199601-284130.

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Fukutoku-Oka-no-Ba

Japan

24.285°N, 141.481°E; summit elev. -29 m

All times are local (unless otherwise noted)


On 12, 22, and 23 January, an aviator from the Japan Marine Safety Agency (JMSA) reported distinct discoloration of seawater to yellowish green. Similar discoloration was seen during 25-28 November 1995 (BGVN 20:11/12). Prior to that, discolored seawater was last seen at this location in September 1993.

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: Volcanological Division, Seismological and Volcanological Department, Japan Meteorological Agency (JMA), 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100 Japan.