The East Australia hotspot is a volcanic province in southeast

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. With an area of , Australia is the largest country by ...

which includes the Peak Range in central

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , establishe ...

, the Main Range on the Queensland-

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

border,

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, Laming ...

in New South Wales, and the Newer Volcanics Province (NVP) in

Victoria Victoria most commonly refers to: * Victoria (Australia), a state of the Commonwealth of Australia * Victoria, British Columbia, provincial capital of British Columbia, Canada * Victoria (mythology), Roman goddess of Victory * Victoria, Seychelle ...

and

South Australia South Australia (commonly abbreviated as SA) is a States and territories of Australia, state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest o ...

. 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 Mount Schank is a high dormant volcano 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 ...

and

Mount Gambier Mount Gambier is the second most populated city in South Australia, with an estimated urban population of 33,233 . The city is located on the slopes of Mount Gambier, a volcano in the south east of the state, about south-east of the capital Ad ...

in the NVP. There have been no eruptions on the Australian mainland since European settlement. Unlike most

hotspots Hotspot, Hot Spot or Hot spot may refer to: Places * Hot Spot, Kentucky, a community in the United States Arts, entertainment, and media Fictional entities * Hot Spot (comics), a name for the DC Comics character Isaiah Crockett * Hot Spot (Tra ...

, the East Australia hotspot has explosive eruptions similar to the runny

lava flow Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or un ...

s of the

Hawaii hotspot The Hawaii hotspot is a volcanic hotspot located near the namesake Hawaiian Islands, in the northern Pacific Ocean. One of the best known and intensively studied hotspots in the world, the Hawaii plume is responsible for the creation of the H ...

, the

Iceland hotspot The Iceland hotspot is a hotspot which is partly responsible for the high volcanic activity which has formed the Iceland Plateau and the island of Iceland. Iceland is one of the most active volcanic regions in the world, with eruptions occu ...

and the

Réunion hotspot The Réunion hotspot is a volcanic hotspot which currently lies under the island of Réunion in the Indian Ocean. The Chagos-Laccadive Ridge and the southern part of the Mascarene Plateau are volcanic traces of the Réunion hotspot. The hotsp ...

. The hotspot is thought to be explosive because

basalt Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90 ...

magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natura ...

interacts with groundwater in aquifers below the surface producing violent phreatomagmatic eruptions. The cause of volcanism in the area is uncertain. Theories typically fall into one of two categories: the

mantle plume A mantle plume is a proposed mechanism of convection within the Earth's mantle, hypothesized to explain anomalous volcanism. Because the plume head partially melts on reaching shallow depths, a plume is often invoked as the cause of volcanic hot ...

theory and the

plate theory In continuum mechanics, plate theories are mathematical descriptions of the mechanics of flat plates that draws on the theory of beams. Plates are defined as plane structural elements with a small thickness compared to the planar dimensions. ...

. On the basis of the long duration of volcanic activity, its vast lateral extent,

geochemistry Geochemistry is the science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems such as the Earth's crust and its oceans. The realm of geochemistry extends beyond the Earth, encompassing th ...

of lavas, and

seismic Seismology (; from Ancient Greek σεισμός (''seismós'') meaning "earthquake" and -λογία (''-logía'') meaning "study of") is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other ...

data, it has been proposed that the region is underlain by one or more deep mantle plumes which have forced

up through points of weakness in the

Indo-Australian Plate The Indo-Australian Plate is a major tectonic plate that includes the continent of Australia and the surrounding ocean and extends northwest to include the Indian subcontinent and the adjacent waters. It was formed by the fusion of the Indian an ...

as it has moved northward over the source. The lack of clear age progression across the province and the orientation of the NVP, which is orthogonal to plate motion, are inconsistent with plume models. Furthermore, seismic anomalies terminate at a depth of around 200 km, making the presence of a mantle plume unlikely. Various tectonic causes have been proposed. Some studies have argued that volcanic activity results from a combination of edge-driven convection (small-scale, shallow

mantle convection Mantle convection is the very slow creeping motion of Earth's solid silicate mantle as convection currents carrying heat from the interior to the planet's surface. The Earth's surface lithosphere rides atop the asthenosphere and the two form ...

caused by a change in lithospheric thickness at the continental margin where thick continental

lithosphere A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust and the portion of the upper mantle that behaves elastically on time scales of up to thousands of years ...

meets thinner oceanic lithosphere) and decompression of the crust from normal faulting caused by plate stresses. Another view is that extension from stresses brought about by changes in plate boundary configurations has caused severe lithospheric thinning resulting in decompression melting of the

asthenosphere The asthenosphere () is the mechanically weak and ductile region of the upper mantle of Earth. It lies below the lithosphere, at a depth between ~ below the surface, and extends as deep as . However, the lower boundary of the asthenosphere is ...

. Both of these models invoke shallow processes closely related to the operation of

plate tectonics Plate tectonics (from the la, label= Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of larg ...

and so fall under the plate theory. Other models combine both plume and plate-tectonic processes.

References

External links

Volcanoes & Earthquakes in SE Australia from the University of Western Australia
{{DEFAULTSORT:East Australia Hotspot Hotspots (geology)

See also

References

External links