Yantarni Volcano
Encyclopedia
Yantarni Volcano is an andesitic
stratovolcano
in the U.S. state
of Alaska
. It is located on the Alaska Peninsula
, in the Aleutian Range
. It is between Mount Aniakchak
and Chiginadak volcanoes. The volcano was not discovered until 1979 due to its remote location, lack of documented historic activity and its rather modest summit elevation. The mountain was named after nearby Yantarni Bay which in turn was named by Russian explorers after the abundance of yantar
in the area.
time with extrusion of andesitic lava
flows, perhaps from multiple vents. By the late Pleistocene, central-vent volcanism had initiated construction of a small stratovolcano. .
, between 2 and 3.5 ka, during the only Holocene event.
The eruption was similar to that of Mount St. Helens
. and was followed by the emplacement of 1 cu km of pyroclastic flow
s related to growth of the summit lava dome
. It had a VEI=5
Andesite
Andesite is an extrusive igneous, volcanic rock, of intermediate composition, with aphanitic to porphyritic texture. In a general sense, it is the intermediate type between basalt and dacite. The mineral assemblage is typically dominated by plagioclase plus pyroxene and/or hornblende. Magnetite,...
stratovolcano
Stratovolcano
A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions...
in the U.S. state
U.S. state
A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...
of Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
. It is located on the Alaska Peninsula
Alaska Peninsula
The Alaska Peninsula is a peninsula extending about to the southwest from the mainland of Alaska and ending in the Aleutian Islands. The peninsula separates the Pacific Ocean from Bristol Bay, an arm of the Bering Sea....
, in the Aleutian Range
Aleutian Range
The Aleutian Range is a major mountain range of southwest Alaska, extending from Chakachamna Lake to Unimak Island, at the tip of the Alaska Peninsula. It includes all of the mountains of the Peninsula. It is especially notable for its large number of active volcanoes, which are also part of the...
. It is between Mount Aniakchak
Mount Aniakchak
Mount Aniakchak is a 3,700 year old volcanic caldera located in the Aleutian Range of Alaska, United States. The area around the volcano is the Aniakchak National Monument and Preserve, maintained by the National Park Service...
and Chiginadak volcanoes. The volcano was not discovered until 1979 due to its remote location, lack of documented historic activity and its rather modest summit elevation. The mountain was named after nearby Yantarni Bay which in turn was named by Russian explorers after the abundance of yantar
Amber
Amber is fossilized tree resin , which has been appreciated for its color and natural beauty since Neolithic times. Amber is used as an ingredient in perfumes, as a healing agent in folk medicine, and as jewelry. There are five classes of amber, defined on the basis of their chemical constituents...
in the area.
Geology
The current cycle of eruptive activity began in middle PleistocenePleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
time with extrusion of andesitic lava
Lava
Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...
flows, perhaps from multiple vents. By the late Pleistocene, central-vent volcanism had initiated construction of a small stratovolcano. .
800 BCE ± 500 years eruption
The cone was breached sometime in the late HoloceneHolocene
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"...
, between 2 and 3.5 ka, during the only Holocene event.
The eruption was similar to that of Mount St. Helens
1980 eruption of Mount St. Helens
The 1980 eruption of Mount St. Helens, a stratovolcano located in Washington state, in the United States, was a major volcanic eruption. The eruption was the only significant one to occur in the contiguous 48 U.S. states since the 1915 eruption of Lassen Peak in California...
. and was followed by the emplacement of 1 cu km of 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 related to growth of the summit lava dome
Lava dome
|250px|thumb|right|Image of the [[rhyolitic]] lava dome of [[Chaitén Volcano]] during its 2008–2009 eruption.In volcanology, a lava dome is a roughly circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano...
. It had a VEI=5
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....