McDonald Islands
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The McDonald Islands are an uninhabited archipelago in the southern Indian Ocean in the vicinity of Heard Island. Together with Heard Island, they make up the Australian external territory of Heard Island and McDonald Islands. The McDonald Islands are the emergent peaks of submarine volcanoes and are Australian external territory. Prior to 1992, there had not been an eruption in the previous 75,000 years.
Morphology
The McDonald Islands comprise three islands: McDonald Island, Flat Island, Needle Island, and Meyer Rock. The islands are mostly composed of phonolitic low-silica pumice, dikes and lava domes, and sit atop a submarine plateau, the Kerguelen Plateau. They are located about 75 km from Heard Island.McDonald Island is the largest of the islands, at around in area. It has been the main focus of volcanic activity in recent times. Prior to 1996, McDonald Island had been a flat green island whose pumice beaches provided a great nesting area for penguin breeding. The island now has two main peaks, Maxwell Hill and Samarang Hill - the highest is Maxwell Hill at.
Flat Island was originally a low-lying island adjacent to McDonald Island. It as since merged with McDonald Island as a result of volcanic activity since the 1980s.
Needle Island is a small, pinnacle rock or outcrop located about 0.2 nautical miles of McDonald Island, just offshore.
Meyer Island is a pinnacle rock that sits about 1 nautical mile northwest of McDonald Island, making it the most distant of these features relative to the main island.
Eruptions
Prior to 1992, no eruptions had taken place at the McDonald Islands volcano for 75,000 years. A series of eruptions began in 1992.1992 eruption
The first recorded eruption from the McDonalds was from a submarine vent in December 1992. The eruption was probably the cause of pumice that washed up on the shore of Heard Island.1996–1997 eruption
Fresh eruptions were reported in December 1996 when a vapour plume was noticed by an aeroplane pilot.The plume was thought to have originated from Heard Island's Big Ben cone. However, on 18 March 1997 the crew of a passing ship heading for Heard Island reported that steam rose vigorously from a fissure on McDonald Island's steep north face; steam also vented from the island's north summit. Steam vented from a rubble-covered slope, indicating that a lava flow or pyroclastic flow had occurred.
On 2 April 1997, the crew of another ship noted that steam continued to vent from the fissure, rising from the summit and flanks of the island. That crew also observed lava flows travelling down gullies; the lava flows covered a significant area of the north part of the island. Sulphur deposits were also discovered and fresh pumice washed up on Heard Island. The eruption is estimated to have ended sometime in January–March 1997.