East Australia hotspot
Encyclopedia
Hotspot (geology)
The places known as hotspots or hot spots in geology are volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the mantle elsewhere. They may be on, near to, or far from tectonic plate boundaries. There are two hypotheses to explain them...
that forces magma
Magma
Magma is a mixture of molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in...
up at weak spots in the Indo-Australian Plate
Indo-Australian Plate
The Indo-Australian Plate is a major tectonic plate that includes the continent of Australia and surrounding ocean, and extends northwest to include the Indian subcontinent and adjacent waters...
to form volcano
Volcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...
es in Eastern Australia. There have been no eruptions in Australia during historic times. It does not produce a single chain of volcanoes like the Hawaiian Islands
Hawaiian Islands
The Hawaiian Islands are an archipelago of eight major islands, several atolls, numerous smaller islets, and undersea seamounts in the North Pacific Ocean, extending some 1,500 miles from the island of Hawaii in the south to northernmost Kure Atoll...
. Tweed Volcano
Tweed Volcano
Tweed Volcano was an early Miocene shield volcano in northeastern New South Wales, Australia. In the course of about three million years, Tweed Volcano was formed over the East Australia hotspot when this part of the continent passed over it around 23 million years ago...
in New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
is a large shield volcano
Shield volcano
A shield volcano is a type of volcano usually built almost entirely of fluid lava flows. They are named for their large size and low profile, resembling a warrior's shield. This is caused by the highly fluid lava they erupt, which travels farther than lava erupted from more explosive volcanoes...
that was formed by the hotspot about 23 million years ago and has one of the biggest erosion caldera
Caldera
A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption, such as the one at Yellowstone National Park in the US. They are sometimes confused with volcanic craters...
s in the world. The most recent eruptions were about 5,000 years ago and formed the volcanoes Mount Schank
Mount Schank
Mount Schank is an inactive maar volcano in the south-east of South Australia, near Mount Gambier. It was named by James Grant in 1800 after Admiral John Schank, designer of Grant's ship, the HMS Lady Nelson....
, Mount Gambier
Mount Gambier (volcano)
Mount Gambier 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 Brownes Lake...
and Mount Napier
Mount Napier
Mount Napier in Victoria, Australia, one of the youngest volcanoes in Australia, last erupted about 5,290 BCE. Mount Napier State Park is located 270 kilometres west of Melbourne and 17 km south of Hamilton. The Mount Napier Lava Flow reached nearby Mount Eccles which is 25 km...
in the Newer Volcanics Province
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 with over 400 vents and contains the youngest volcanoes in Australia...
.
Unlike most hotspots, the East Australia hotspot has explosive eruptions, as well as the runny lava flows of the Hawaii hotspot, the Iceland hotspot
Iceland hotspot
The Iceland hotspot is a hotspot which is partly responsible for the high volcanic activity which has formed the island of Iceland.-Description:...
and the Réunion hotspot
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 hotspot is explosive because basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
ic magma
Magma
Magma is a mixture of molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in...
interacts with groundwater in aquifers below the surface producing violent phreatomagmatic eruptions.