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The Antarctica Region
Antarctica, Earth's southernmost continent, is the largest CAVW region in land area and–with no permanent residents–easily the smallest in population. This region also includes the South Sandwich Islands and other island groups adjacent to Antarctica. It is the only region unblemished by a single fatal eruption; more a reflection on its low resident population than on its hazard mitigation efforts.
Although the continent of Antarctica was not discovered until 1840 (by the Wilkes expedition, 12 hours before the French), several nearby island groups now part of region 19 were recognized earlier. The northernmost of these, the South Sandwich Islands or Scotia Arc, was discovered on Captain Cook's 1772-75 voyages, and one of the group–Zavodovsky Island–was issuing a black ash cloud from its summit when discovered by Bellinghausen in 1819. Several other eruptions were reported from these islands in the following years, when fur sealing was at its peak in the region. Sometime between 1825 and 1828, sealers documented an eruption at Deception Island, a natural harbor formed by caldera collapse. And in 1839 an eruption was in progress in the Balleny Islands when they were first discovered by whalers. Two years later, Mount Erebus was erupting when this, the most active volcano in the region, was first sighted.
There followed nearly 60 years of little exploration, although whaling ships continued to work the region through the 19th century. Exploration resumed with a vengeance in 1895, with the next two decades known as the 'heroic age' in Antarctica. Additional exploration between the World Wars, during the 1957-58 International Geophysical Year, and since the signing of the Antarctic Treaty in 1961 has contributed greatly to understanding this vast region, but it is clear that its historical record of volcanism is both short and very incomplete.
The Antarctic plate, largely aseismic and immobile, is broken internally by large rift structures which have produced one of the world's largest alkalic volcanic provinces. The 3200-km-long West Antarctic rift system is comparable in size to the better-known East African rift. Volcanic constructs range from large basaltic shields to small monogenetic vents; the presence of the continental icesheet has resulted in a larger volume of hyaloclastite rocks than perhaps any other subaerial volcanic region. The only subduction-related volcanoes within or adjacent to the Antarctic plate form the South Sandwich and South Shetland Islands.
Despite its large size, Antarctica ranks below all other regions in number of dated eruptions, and only the Pacific and Atlantic Ocean regions have fewer historically active volcanoes. The region has produced no known large Holocene eruptions (VEI ?4 or lava ?1 km3) with the possible exception of a 0.19-0.31 km3 subglacial tephra deposit from the Hudson Mountains estimated to have been erupted about 200 BC from ice thickness data. Antarctica contains one of the few volcanoes with long-term lava lake activity, which has attracted researchers to this 3794-m-high volcano overlooking the McMurdo Antarctic research station. Antarctica's historical record is brief, and nearly half of its known eruptions are from this century. Precise dating of past eruptions is difficult–much of the landscape is ice-covered, travel is daunting, and the wood needed for radiocarbon dating does not grow in this extreme climate–and the region has the highest proportion of volcanoes with uncertain status. Satellite imagery, however, has helped document recent activity that would otherwise go unnoticed. MODIS thermal alerts from NASA's first Earth Observing System (EOS) satellite 'Terra' have detected 21st century explosive and effusive eruptions on the glacier-covered surface of Montagu Island in the South Sandwich Islands. Antarctic ice sheets have proved a valuable resource for detailed dating of ice cores that contain ash and aerosol layers from both Antarctic and distant tropical and sub-tropical volcanoes and provide critical information regarding the impact of volcanism on global climate patterns during the Holocene.
List of Holocene volcanoes in the Antarctica region.