East Australia hotspot

The East Australia hotspot is a volcanic hotspot that forces magma up at weak spots in the Indo-Australian Plate to form volcanoes in Eastern Australia. It does not produce a single chain of volcanoes like the Hawaiian Islands.[1] Unlike most hotspots, the East Australia hotspot has explosive eruptions, as well as the runny lava flows of the Hawaii hotspot, the Iceland hotspot and the Réunion hotspot. The hotspot is explosive because basaltic magma interacts with groundwater in aquifers below the surface producing violent phreatomagmatic eruptions.

Tweed Volcano in New South Wales is a large shield volcano that was formed by the hotspot about 23 million years ago and has one of the biggest erosion calderas in the world.

A number of the volcanoes in the province have erupted since Aboriginal settlement (46,000 BP). The most recent eruptions were about 5,600 years ago, and memories of them survive in Aboriginal folklore. These eruptions formed the volcanoes Mount Schank and Mount Gambier in the Newer Volcanics Province. There have been no eruptions on the Australian mainland since European settlement.

Hotspots
The East Australia hotspot is marked 30 on map.
Mtschank
View inside the crater of Mount Schank from the rim

See also

References

  1. ^ "Volcanoes of Australia". Volcano World, Department of Geosciences at Oregon State University. Retrieved 24 January 2010.

External links

Australia

Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. It is the largest country in Oceania and the world's sixth-largest country by total area. The neighbouring countries are Papua New Guinea, Indonesia, and East Timor to the north; the Solomon Islands and Vanuatu to the north-east; and New Zealand to the south-east. The population of 26 million is highly urbanised and heavily concentrated on the eastern seaboard. Australia's capital is Canberra, and its largest city is Sydney. The country's other major metropolitan areas are Melbourne, Brisbane, Perth, and Adelaide.

Indigenous Australians inhabited the continent for about 65,000 years prior to European discovery with the arrival of Dutch explorers in the early 17th century, who named it New Holland. In 1770, Australia's eastern half was claimed by Great Britain and initially settled through penal transportation to the colony of New South Wales from 26 January 1788, a date which became Australia's national day. The population grew steadily in subsequent decades, and by the time of an 1850s gold rush, most of the continent had been explored and an additional five self-governing crown colonies established. On 1 January 1901, the six colonies federated, forming the Commonwealth of Australia. Australia has since maintained a stable liberal democratic political system that functions as a federal parliamentary constitutional monarchy, comprising six states and ten territories.

Being the oldest, flattest and driest inhabited continent, with the least fertile soils, Australia has a landmass of 7,617,930 square kilometres (2,941,300 sq mi). A megadiverse country, its size gives it a wide variety of landscapes, with deserts in the centre, tropical rainforests in the north-east and mountain ranges in the south-east. Its population density, 2.8 inhabitants per square kilometre, remains among the lowest in the world. Australia generates its income from various sources including mining-related exports, telecommunications, banking, and manufacturing.Australia is a highly developed country, with the world's 14th-largest economy. It has a high-income economy, with the world's tenth-highest per capita income. It is a regional power and has the world's 13th-highest military expenditure. Australia has the world's eighth-largest immigrant population, with immigrants accounting for 29% of the population. Having the third-highest human development index and the eighth-highest ranked democracy globally, the country ranks highly in quality of life, health, education, economic freedom, civil liberties and political rights, with all its major cities faring well in global comparative livability surveys. Australia is a member of the United Nations, G20, Commonwealth of Nations, ANZUS, Organisation for Economic Co-operation and Development (OECD), World Trade Organization, Asia-Pacific Economic Cooperation, Pacific Islands Forum, and the ASEAN Plus Six mechanism.

Byron Bay, New South Wales

Byron Bay is a beachside town located in the far-northeastern corner of the state of New South Wales, Australia. It is located 772 kilometres (480 mi) north of Sydney and 165 kilometres (103 mi) south of Brisbane. Cape Byron, a headland adjacent to the town, is the easternmost point of mainland Australia. At the 2016 census, the town had a permanent population of 9,246. It is the largest town of Byron Shire, though not the shire's administrative centre (which is Mullumbimby).

The local Arakwal Aboriginal people's name for the area is Cavvanbah, meaning "meeting place". Lieutenant James Cook named Cape Byron after Royal Navy officer John Byron, circumnavigator of the world and grandfather of the poet Lord Byron.

Glass House Mountains

The Glass House Mountains are a cluster of thirteen hills that rise abruptly from the coastal plain on the Sunshine Coast, Queensland, Australia. The highest hill is Mount Beerwah at 556 metres above sea level, but the most identifiable of all the hills is Mount Tibrogargan which from certain angles bears a resemblance to a face staring east towards the ocean. The Glass House Mountains are located near Beerburrum State Forest and Steve Irwin Way. From Brisbane, the mountains can be reached by following the Bruce Highway north and taking the Glass House Mountains tourist drive turn-off onto Steve Irwin Way. The trip is about one hour from Brisbane. The Volcanic peaks of the Glass House Mountains rise dramatically from the surrounding Sunshine Coast landscape. They were formed by intrusive plugs, remnants of volcanic activity that occurred 26-27 million years ago. Molten rock filled small vents or intruded as bodies beneath the surface and solidified into land rocks. Millions of years of erosion have removed the surrounding exteriors of volcanic cores and softer sandstone rock.

Whilst the traditional names for the hills themselves are very old, the term 'Glasshouse Mountains' was given more recently by explorer Lieutenant James Cook on 17 May 1770. The peaks reminded him of the glass furnaces in his home county of Yorkshire. Matthew Flinders explored the area and climbed Mount Beerburrum after sailing along Pumicestone Passage in 1799. The Glass House Mountains National Landscape was added to the Australian National Heritage List on 3 August 2006. In the land between the peaks, pineapple and poultry farming, as well as commercial forestry and quarrying are the main land uses.In 2009 as part of the Q150 celebrations, the Glass House Mountains was announced as one of the Q150 Icons of Queensland for its role as a "Natural attraction".

Hotspot (geology)

In geology, the places known as hotspots or hot spots are volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the surrounding mantle. Their position on the Earth's surface is independent of tectonic plate boundaries. There are two hypotheses that attempt to explain their origins. One suggests that hotspots are due to mantle plumes that rise as thermal diapirs from the core–mantle boundary. The other hypothesis is that lithospheric extension permits the passive rising of melt from shallow depths. This hypothesis considers the term "hotspot" to be a misnomer, asserting that the mantle source beneath them is, in fact, not anomalously hot at all. Well-known examples include the Hawaii, Iceland and Yellowstone hotspots.

Mount Gambier (volcano)

Mount Gambier (also known as Ereng Balam, meaning eagle hawk) is a maar complex in South Australia associated with the Newer Volcanics Province. It contains four lake-filled maars called Blue Lake, Valley Lake, Leg of Mutton Lake, and Browns Lake. Both Brown and Leg of Mutton lakes are dry in recent years, due to the lowering of the water table.

It is one of Australia's youngest volcanoes, but estimates of the age have ranged from over 28,000 to less than 4,300.

The most recent estimate, based on radiocarbon dating of plant fibers in the main crater (Blue Lake) suggests an eruption a little before 6000 years ago.

It is believed to be dormant rather than extinct.

Mount Gambier is thought to have formed by a mantle plume centre called the East Australia hotspot which may currently lie offshore.The mountain was sighted by Lieutenant James Grant on 3 December 1800 from the survey brig HMS Lady Nelson and named for Lord James Gambier, Admiral of the Fleet.This area is part of the UNESCO-endorsed Kanawinka Geopark.

Of the original four lakes found within the maars, only two remain. The Leg of Mutton Lake (named for the outline of its shoreline) became permanently dry in the 1990s. Browns Lake suffered a similar fate during the late 1980s. Both these lakes were quite shallow; their demise is attributed to the lowering of the water table as a result of many years of land drainage to secure farmland.

The city of Mount Gambier partially surrounds the maar complex.

Mount Schank

Mount Schank is a 100 m (330 ft) high volcanic cone in the southeast corner of South Australia, near Mount Gambier. It was sighted by James Grant on 3 December 1800 and named after Admiral John Schank, designer of Grant's ship, HMS Lady Nelson.Mount Schank is part of the Newer Volcanics Province, which is the youngest volcanic field in Australia. Mount Schank erupted about 5,000 years ago, around the same time as Mount Gambier. It is a very basic ash cone and the base of the crater does not extend below the water table, so there is no crater lake as with those at Mount Gambier. There are two small subsidiary craters adjacent to the main cone and some lava flows resulting from the eruption. The northern crater is circular, 300 m (980 ft) in diameter and 100 m (330 ft) deep, the older southern crater is 200 m (660 ft) in diameter and partially overlapped by the larger crater.The local Aboriginal Bunganditj people witnessed Mount Schank's eruptions over time. Their creation story about the local volcanic landscape was recorded by a local woman, Christina Smith, in 1880. It tells the tale of Craitbul, a giant, who was looking for a place to live with his wife and two sons. They camped at Mount Muirhead and Mount Schank, but were scared away from both these camps by a moaning bird spirit. They fled to Mount Gambier, leaving their camp ovens (the volcanoes) burning. After some time, water came and filled their ovens, putting them out and driving the spirit away. They continued to live in a cave on the side of Mount Gambier.The site is accessible from the Riddoch Highway about 20 km (12 mi) south of Mount Gambier; there is a small carpark and picnic table, and steps have been placed to facilitate the short but very steep walk to the rim of the crater. It is a fairly simple walk to traverse the rim, though the exposed situation can be treacherous in gusty weather.

Murray Island, Queensland

Murray Island, also called Mer in the native Meriam language, is a small island of volcanic origin, the most easterly inhabited island of the Torres Strait Islands archipelago, just north of the Great Barrier Reef. The island is populated by the Melanesian Meriam people, which has a population of around 485 as of 2006 census. The Murray Group comprises three islands: Murray Island (Mer), Dauar Island (Dauar) and Waier Island (Waier).

There are eight tribes on Mer: Komet, Zagareb, Meuram, Magaram, Geuram, Peibri, Meriam-Samsep, Piadram/Dauer. The organisation of the island is based on the traditional laws of boundary and ownership.

Newer Volcanics Province

The Newer Volcanics Province is a complex of volcanic centres formed by the East Australia hotspot across south-eastern Australia. It has an area of 6,000 square miles (15,000 square km) with over 400 vents and contains the youngest volcanoes in Australia. The youngest eruptions in the volcanic field took place at Mount Schank and Mount Gambier about 5000 years ago, when explosive activity formed several maars and associated lava flows.Volcanoes within the province include:

Mount Schank

Mount Napier

Mount Gambier (including Blue Lake)

Tower Hill

Mount Elephant

Mount Eccles

Mount Leura

Mount Noorat

Mount Buninyong

Lake Bullen Merri

Lake Purrumbete

Red Rock

Tweed Volcano

Tweed Volcano is a partially eroded Early Miocene shield volcano located in northeastern New South Wales, which formed when this region of Australia passed over the East Australia hotspot around 23 million years ago. Mount Warning, Lamington Plateau and the Border Ranges between New South Wales and Queensland are among the remnants of this volcano that was originally over 100 kilometres (62 mi) in diameter and nearly twice the height of Mount Warning today, at 1,156 metres (3,793 ft). Despite its size, Tweed Volcano was not a supervolcano; other shield volcanoes - such as on Hawaii - are much larger. In the 23 million years since the volcano was active, erosion has been extensive, forming a large erosion caldera around the volcanic plug of Mount Warning. Its erosion caldera is the largest in the Southern Hemisphere.

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