Report on Macdonald (Undersea Features) — August 1983
Scientific Event Alert Network Bulletin, vol. 8, no. 8 (August 1983)
Managing Editor: Lindsay McClelland.
Macdonald (Undersea Features) Renewed submarine activity
Please cite this report as:
Global Volcanism Program, 1983. Report on Macdonald (Undersea Features). In: McClelland, L. (ed.), Scientific Event Alert Network Bulletin, 8:8. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198308-333060.
28.98°S, 140.25°W; summit elev. -39 m
All times are local (unless otherwise noted)
In May, the RSP recorded seismicity from renewed eruptive activity at Macdonald. Its eight previous eruptions had begun with explosive events, but the May activity did not, and probably was a continuation of the March eruption. Reconaissance by a Marine National Française vessel did not show a perceptible increase in the volcano's summit altitude since the bathymetric survey of February 1982.
Further Reference. Talandier, J. and Okal, E.A., 1984, New Surveys of Macdonald Seamount Following Volcanoseismic Activity, 1977-1983; Geophysical Research Letters, v. 1, no. 9, p. 813-816.
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, Lab. de Géophysique, Tahiti.