Billy Mitchell (volcano)
Encyclopedia
Billy Mitchell is a volcano
located in the central part of the island of Bougainville
, just northeast of the Bagana Volcano
, in Papua New Guinea
. It is a small, pyroclastic shield
truncated by a 2 km wide caldera
filled by a crater lake
.
The last two major eruptions were more than 400 (in 1580 AD ± 20 years) and 900 years ago. They were among the largest Holocene
eruptions in Papua New Guinea. Both were explosive eruption
s with a Volcanic Explosivity Index
of at least 5. The eruption that occurred in 1580 AD ± 20 years produced pyroclastic flow
s and caused the formation of its caldera
.
The ignimbrite
deposit from that eruption, which had a VEI of 6, extends 22 kilometres (13.7 mi) from the caldera to the coast, and its volume is around 10 cubic kilometres (2.4 cu mi).
The volcano is named for American general Billy Mitchell.
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...
located in the central part of the island of Bougainville
Bougainville Island
Bougainville Island is the main island of the Autonomous Region of Bougainville of Papua New Guinea. This region is also known as Bougainville Province or the North Solomons. The population of the province is 175,160 , which includes the adjacent island of Buka and assorted outlying islands...
, just northeast of the Bagana Volcano
Bagana
Bagana is an active volcano located in the central part of the island of Bougainville, Papua New Guinea, the largest island of the Solomon group. It is the most active volcano in the country. Just northeast of Bagana is the volcano crater lake Billy Mitchell. Bagana is one of 17 post-Miocene...
, in Papua New Guinea
Papua New Guinea
Papua New Guinea , officially the Independent State of Papua New Guinea, is a country in Oceania, occupying the eastern half of the island of New Guinea and numerous offshore islands...
. It is a small, pyroclastic shield
Pyroclastic shield
In volcanology, a pyroclastic shield or terrestrial ignimbrite shield is an uncommon type of shield volcano. Unlike most shield volcanoes, pyroclastic shields are formed mostly of pyroclastic and highly explosive eruptions rather than relatively fluid basaltic lava issuing from vents or fissures on...
truncated by a 2 km wide 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...
filled by a crater lake
Crater lake
A crater lake is a lake that forms in a volcanic crater or caldera, such as a maar; less commonly and with lower association to the term a lake may form in an impact crater caused by a meteorite. Sometimes lakes which form inside calderas are called caldera lakes, but often this distinction is not...
.
The last two major eruptions were more than 400 (in 1580 AD ± 20 years) and 900 years ago. They were among the largest Holocene
Holocene
The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...
eruptions in Papua New Guinea. Both were explosive eruption
Explosive eruption
An explosive eruption is a volcanic term to describe a violent, explosive type of eruption. Mount St. Helens in 1980 was an example. Such an eruption is driven by gas accumulating under great pressure. Driven by hot rising magma, it interacts with ground water until the pressure increases to the...
s with a Volcanic Explosivity Index
Volcanic Explosivity Index
The Volcanic Explosivity Index was devised by Chris Newhall of the U.S. Geological Survey and Stephen Self at the University of Hawaii in 1982 to provide a relative measure of the explosiveness of volcanic eruptions....
of at least 5. The eruption that occurred in 1580 AD ± 20 years produced pyroclastic flow
Pyroclastic flow
A pyroclastic flow is a fast-moving current of superheated gas and rock , which reaches speeds moving away from a volcano of up to 700 km/h . The flows normally hug the ground and travel downhill, or spread laterally under gravity...
s and caused the formation of its 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...
.
The ignimbrite
Ignimbrite
An ignimbrite is the deposit of a pyroclastic density current, or pyroclastic flow, a hot suspension of particles and gases that flows rapidly from a volcano, driven by a greater density than the surrounding atmosphere....
deposit from that eruption, which had a VEI of 6, extends 22 kilometres (13.7 mi) from the caldera to the coast, and its volume is around 10 cubic kilometres (2.4 cu mi).
The volcano is named for American general Billy Mitchell.
See also
- List of volcanoes in Papua New Guinea
- Timetable of major worldwide volcanic eruptionsTimetable of major worldwide volcanic eruptionsThis article is a list of volcanic eruptions of approximately at least magnitude 6 on the Volcanic Explosivity Index or equivalent sulfur dioxide emission around the Quaternary period. Some cooled the global climate; the extent of this effect depends on the amount of sulfur dioxide emitted...