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Report on Macdonald (Undersea Features) — May 1987

Scientific Event Alert Network Bulletin, vol. 12, no. 5 (May 1987)
Managing Editor: Lindsay McClelland.

Macdonald (Undersea Features) Acoustic waves from moderate eruption

Please cite this report as:

Global Volcanism Program, 1987. Report on Macdonald (Undersea Features). In: McClelland, L. (ed.), Scientific Event Alert Network Bulletin, 12:5. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198705-333060.

Volcano Profile |  Complete Bulletin


Macdonald

Undersea Features

28.98°S, 140.25°W; summit elev. -39 m

All times are local (unless otherwise noted)


An eruption was detected by acoustic waves (T-phase) received by RSP stations on 4 June. Explosions began around [0400] and were followed by a continuous noise of variable level with some episodes of stronger intensity. The eruption ended ~4 hours later [but see 12:09]. This eruption was the 15th recorded since 1977 and one of the shortest of the moderate-intensity eruptions.

Geologic Background. Discovered by the detection of teleseismic waves in 1967, Macdonald seamount (also known as Tamarii seamount) rises from a depth of about 1800 m to within 27 m of the sea surface at the eastern end of the Austral Islands. The alkali-basaltic submarine volcano marks the site of a hotspot that was the source of the Austral-Cook island chain. The summit of the seamount, named after volcanologist Gordon Macdonald, consists of a flat plateau about 100 x 150 m wide with an average depth of about 40 m. The summit plateau is capped with spatter cones that form steep-sided pinnacles. Most eruptions have been seismically detected, but in 1987 and 1989 pumice emission was observed from research vessels. Pumice rafts observed in the South Pacific in 1928 and 1936 may also have originated here.

Information Contacts: J. Talandier, LDG Tahiti.