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Report on Supply Reef (United States) — September 1985


Supply Reef

Scientific Event Alert Network Bulletin, vol. 10, no. 9 (September 1985)
Managing Editor: Lindsay McClelland.

Supply Reef (United States) Discolored water but no eruption plume

Please cite this report as:

Global Volcanism Program, 1985. Report on Supply Reef (United States) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 10:9. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198509-284142



Supply Reef

United States

20.13°N, 145.1°E; summit elev. -8 m

All times are local (unless otherwise noted)


On 2 September, a Continental Air Micronesia pilot observed a zone of brown and light green discolored water about 3 km in diameter, centered about 30 km S of Farallon de Pajaros. No eruption plume was seen by the pilot and inspection of satellite images for several days after 2 September revealed no visible plumes. Cloudy weather obscured the area in the days immediately preceding 2 September. No other reports of activity have been received.

The location of the 1985 activity is approximate, but is not inconsistent with the position of the 1969 eruption and the seamount.

Geological Summary. Supply Reef is a conical submarine volcano in the northern Mariana Islands that rises to within 8 m of the surface. The andesitic seamount lies about 10 km NW of the Maug Islands, the emergent summit of a submarine volcano that is joined to Supply Reef by a low saddle at a depth of about 1800 m. Supply Reef was mapped as Quaternary; living corals on the crater rim suggest that it is either dormant or extinct (Corwin, 1971). Several submarine eruptions have been detected by sonar signals originating from points very approximately located at distances of 15-25 km NW.

Information Contacts: N. Banks, CVO, Vancouver, WA; W. Gould, NOAA/NESDIS.