Billy Mitchell is a
pyroclastic shield
In volcanology, a pyroclastic shield or 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 basalti ...
in the central part of the island of
Bougainville, just north-east of the
Bagana Volcano
Bagana is an active volcanic cone located in the centre of the island of Bougainville, Papua New Guinea, the largest island of the Solomon group. It is the most active volcano in the country, occupying a remote portion of central Bougainville ...
in
Papua New Guinea. It is a small
pyroclastic shield
In volcanology, a pyroclastic shield or 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 basalti ...
truncated by a 2 km wide
caldera
A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...
filled by a
crater lake.
It is named after
Billy Mitchell, a 20th-century
United States Army general who is regarded as the father of the
United States Air Force.
The last two major eruptions were in 1580 AD ± 20 years and about 1030 AD. They were among the largest
Holocene eruptions in Papua New Guinea. Both were
explosive eruption
In volcanology, an explosive eruption is a volcanic eruption of the most violent type. A notable example is the 1980 eruption of Mount St. Helens. Such eruptions result when sufficient gas has dissolved under pressure within a viscous magma such ...
s with a
Volcanic Explosivity Index of at least 5. The 1580 AD ± 20 years eruption produced
pyroclastic flows and probably formed its
caldera
A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...
. The
ignimbrite deposit from that eruption, which had a VEI of 6, extends from the caldera to the coast, and its volume is around .
[
]
Caldera lake
Billy Mitchell caldera lake is about 1,013 m above sea level, has total surface area , and the maximum depth approximately 88.3 m. The only fish species in the lake is the eel Anguilla megastoma.
Billy Mitchell lake drains into the Tekan River.Billy Mitchell volcano
VolcanoDiscovery
See also
*
List of volcanoes in Papua New Guinea
*
Mount Billy Mitchell (Chugach Mountains)
*
Timeline of volcanism on Earth
References
External links
Photo of the Billy Mitchell Crater Lake*
Mountains of Papua New Guinea
Volcanoes of Bougainville Island
Lakes of Papua New Guinea
Pyroclastic shields
Volcanic crater lakes
VEI-6 volcanoes
16th-century volcanic events
Shield volcanoes of Papua New Guinea
{{Bougainville-geo-stub