Report on Fukutoku-Oka-no-Ba (Japan) — October 1992
Bulletin of the Global Volcanism Network, vol. 17, no. 10 (October 1992)
Managing Editor: Lindsay McClelland.
Fukutoku-Oka-no-Ba (Japan) Pumice ejected by submarine eruption
Please cite this report as:
Global Volcanism Program, 1992. Report on Fukutoku-Oka-no-Ba (Japan) (McClelland, L., ed.). Bulletin of the Global Volcanism Network, 17:10. Smithsonian Institution.
24.285°N, 141.481°E; summit elev. -29 m
All times are local (unless otherwise noted)
A dark plume was observed [in the air above Fukutoku-Okanoba] by fishing crews at about 0800 on 10 November. An overflight by the JMSA from 1315 to 1350 revealed discolored pale-green water in a narrow fan shape to 10 km NNW from the volcano. Brown pumice was seen but no ejections were observed at that time. An overflight on 12 November between 1215 and 1250 revealed that water discoloration was reduced to a zone extending 1 km NW without floating pumice, indicating a decrease in activity. An area of discolored water 2 km long was seen in August but no discoloration was observed during the last overflight before the eruption, on 22 October.
Geological Summary. 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.