Heard Island and McDonald Islands - Geography

Geography

Heard Island, by far the largest of the group, is a 368-square-kilometre (142 sq mi) bleak and mountainous island located at 53°06′00″S 73°31′00″E / 53.1°S 73.5166667°E / -53.1; 73.5166667. Its mountains are covered in glaciers (the island is 80% covered with ice) and dominated by Mawson Peak, a 2,745-metre (9,006 ft) high complex volcano which forms part of the Big Ben massif. A July 2000 satellite image from the University of Hawaii's Institute of Geophysics and Planetology (HIGP) Thermal Alert Team, University of Hawai'i showed an active 2-kilometre (1.2 mi) long (and 50–90 metres/164–295 feet wide) lava flow trending south-west from the summit of Big Ben.

Mawson Peak is one of only 2 active volcanoes in Australian territory, the other being McDonald Island. It is also one of the highest Australian mountains (higher than Mount Kosciuszko); surpassed only by peaks in the Antarctic territory. A long thin sand and gravel spit named "Elephant Spit" extends from the eastern end of the island. There is a small group of islets and rocks about 10 kilometres (6 mi) north of Heard Island, consisting of Shag Islet, Sail Rock, Morgan Island and Black Rock. They total about 1.1 square kilometres (0.4 sq mi) in area.

The McDonald Islands are located 44 kilometres (27 mi) to the west of Heard Island at 53°02′20″S 72°36′04″E / 53.03889°S 72.60111°E / -53.03889; 72.60111. The islands are small and rocky. In 1980 they consisted of McDonald Island (186 metres (610 ft) high), Flat Island (55 metres (180 ft) high) and Meyer Rock (170 metres (560 ft) high). They totalled approximately 2.5 square kilometres (1.0 sq mi) in area, where McDonald Island was 1.13 square kilometres (0.4 sq mi) large. Like Heard Island, they were surface exposures of the Kerguelen Plateau.

The volcano on McDonald Island, after being dormant for 75,000 years, became active in 1992 and has erupted several times since. A satellite image taken in 2004 showed that recent volcanic activity had joined McDonald Island and Flat Island into one island and generally doubled the land size of the resultant island. As a result of volcanic activity between November 2000 and the end of 2001 the area of McDonald Island increased to 2.45 square kilometres (0.9 sq mi) and the highest summit now was at least 230 metres (750 ft) high. However, the volcanic activity destroyed nearly all the vegetation on the island. The most recent eruption is thought to have been on 10 August 2005. Currently there is on-going regeneration of vegetation.

Heard Island and the McDonald Islands have no ports or harbours; ships must anchor offshore. The coastline is 101.9 kilometres (63.3 mi), and a 12-nautical-mile (22 km; 14 mi) territorial sea and 200-nautical-mile (370 km; 230 mi) exclusive fishing zone are claimed.

The antipode to the central Mawson Peak of Heard Island is located less than 70 kilometres (43 mi) west by south of Prince Albert, Saskatchewan, Canada.