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 ...
Papua New Guinea
Papua New Guinea (abbreviated PNG; , ; tpi, Papua Niugini; ho, Papua Niu Gini), officially the Independent State of Papua New Guinea ( tpi, Independen Stet bilong Papua Niugini; ho, Independen Stet bilong Papua Niu Gini), is a country i ...
. 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
Crater Lake (Klamath language, Klamath: ''Giiwas'') is a volcanic crater lake in south-central Oregon in the western United States. It is the main feature of Crater Lake National Park and is famous for its deep blue color and water clarity. The ...
. It is named after
Billy Mitchell
William Lendrum Mitchell (December 29, 1879 – February 19, 1936) was a United States Army officer who is regarded as the father of the United States Air Force.
Mitchell served in France during World War I and, by the conflict's end, command ...
, a 20th-century
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
Army
An army (from Old French ''armee'', itself derived from the Latin verb ''armāre'', meaning "to arm", and related to the Latin noun ''arma'', meaning "arms" or "weapons"), ground force or land force is a fighting force that fights primarily on ...
general who is regarded as the father of the
United States Air Force
The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Signal ...
.
The last two major eruptions were in 1580 AD ± 20 years and about 1030 AD. They were among the largest
Holocene
The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...
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 ...
pyroclastic flow
A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average speeds of bu ...
s 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
Ignimbrite is a type of volcanic rock, consisting of hardened tuff. Ignimbrites form from the deposits of pyroclastic flows, which are a hot suspension of particles and gases flowing rapidly from a volcano, driven by being denser than the surrou ...
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
List of volcanoes in Papua New Guinea
This is a list of active and extinct volcanoes in Papua New Guinea.
New Guinea
Admiralty Islands
Bougainville
D'Entrecasteaux Islands
New Britain
New Ireland
Offshore islands
References
* Volcanoes of the World
Ext ...
*
Mount Billy Mitchell (Chugach Mountains)
Mount Billy Mitchell is a prominent peak located in the Chugach Mountains, east of Valdez and west of the Copper River in the U.S. state of Alaska. This mountain forms a prominent and easily visible landmark between mile markers 43 and 51 o ...
*
Timeline of volcanism on Earth
This timeline of volcanism on Earth includes a list of major volcanic eruptions of approximately at least magnitude 6 on the Volcanic explosivity index (VEI) or equivalent sulfur dioxide emission during the Quaternary period (from 2.58 Mya to th ...