Report on McDonald Islands (Australia) — 10 August-16 August 2005
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 10 August-16 August 2005
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2005. Report on McDonald Islands (Australia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 10 August-16 August 2005. Smithsonian Institution and US Geological Survey.
53.03°S, 72.6°E; summit elev. 230 m
All times are local (unless otherwise noted)
The Darwin VAAC issued a precautionary advisory on 10 August warning pilots of the possible presence of low-level ash near McDonald Island. The advisory was based on a press release made by the Australian Minister for the Environment and Heritage, the parent agent of the Australian Antarctic Division. The press release discussed a hotspot at McDonald Island that was visible on satellite imagery on 12 July. The Darwin VAAC did not see ash in satellite imagery.
Geologic Background. Historical eruptions have greatly modified the morphology of the McDonald Islands, located on the Kerguelen Plateau about 75 km W of Heard Island. The largest island, McDonald, is composed of a layered phonolitic tuff plateau cut by phonolitic dikes and lava domes. A possible nearby active submarine center was inferred from phonolitic pumice that washed up on Heard Island in 1992. Volcanic plumes were observed in December 1996 and January 1997 from McDonald Island. During March of 1997 the crew of a vessel that sailed near the island noted vigorous steaming from a vent on the N side of the island along with possible pyroclastic deposits and lava flows. A satellite image taken in November 2001 showed the island to have more than doubled in area since previous reported observations in November 2000. The high point of the island group had shifted to the McDonald's N end, which had merged with Flat Island.