Avachinsky (also known as Avacha or Avacha Volcano or Avachinskaya Sopka) (russian: Авачинская сопка, Авача) is an active
stratovolcano
A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and per ...
in
Russia. It is situated on the
Kamchatka Peninsula in the
Russian Far East. Avachinsky lies within sight of
Petropavlovsk-Kamchatsky, the capital of
Kamchatka Krai
Kamchatka Krai ( rus, Камча́тский край, r=Kamchatsky kray, p=kɐmˈtɕatskʲɪj kraj) is a federal subject of Russia (a krai), situated in the Russian Far East, and is administratively part of the Far Eastern Federal District. Its ...
. Together with neighboring
Koryaksky volcano, it has been designated a
Decade Volcano, worthy of particular study in light of its history of explosive eruptions and proximity to populated areas.
Avachinsky's last eruption occurred in 2008. This eruption was tiny compared to the volcano's major
Volcanic Explosivity Index 4 eruption in 1945.
Geological history
Avachinsky lies on the
Pacific Ring of Fire, at a point where the
Pacific Plate
The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At , it is the largest tectonic plate.
The plate first came into existence 190 million years ago, at the triple junction between the Farallon, Phoenix, and Iza ...
is sliding underneath the
Eurasian Plate at a rate of about /year. A wedge of
mantle
A mantle is a piece of clothing, a type of cloak. Several other meanings are derived from that.
Mantle may refer to:
*Mantle (clothing), a cloak-like garment worn mainly by women as fashionable outerwear
**Mantle (vesture), an Eastern Orthodox ve ...
material lying between the
subducting Pacific Plate and the overlying Eurasian Plate is the source of dynamic volcanism over the whole Kamchatka Peninsula.
The volcano is one of the most active volcanoes on the Kamchatka Peninsula, and began erupting in the middle to late
Pleistocene era. It has a horseshoe-shaped
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 ...
, which formed 30-40,000 years ago in a major
landslide
Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, deep-seated grade (slope), slope failures, mudflows, and debris flows. Landslides occur in a variety of ...
which covered an area of south of the volcano, underlying the city of Petropavlovsk-Kamchatsky. Reconstruction of a new cone inside the caldera occurred in two major eruption phases, 18,000 and 7,000 years ago.
[.]
Avachinsky Volcano.jpg, Seen from base camp.
Image:Avachinsky Summit.jpg, Avachinsky Summit.
Image:Koryaksky and Avachinsky volcanoes from the ISS.jpg, Avachinsky (centre, nearest coast) from space.
Image:Avachinsky Volcano, Kamchatka Peninsula.JPG, Astronaut photograph highlighting the summit crater and snow-covered slopes of the Avachinsky.
Recorded history
In his Journal of Captain Cook's Last Voyage,
John Ledyard
John Ledyard (November 1751 – 10 January 1789) was an American explorer and adventurer.
Early life
Ledyard was born in Groton, Connecticut, in November 1751. He was the first child of Abigail Youngs Ledyard and Capt. John Ledyard Jr, son o ...
records the eruption of Avachinsky on June 15, 1779. He refers to
Koryaksky and Avachinsky as Peter and Paul.
Recent activity
Avachinsky has erupted at least 16 times in
recorded history. Eruptions have generally been explosive, and
pyroclastic flows and
lahar
A lahar (, from jv, ꦮ꧀ꦭꦲꦂ) is a violent type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris and water. The material flows down from a volcano, typically along a river valley.
Lahars are extreme ...
s have tended to be directed to the south west by the breached caldera. The most recent large eruption (
VEI=4) occurred in 1945, when about of
magma was ejected. The volcano has since had small eruptions in 1991 and 2001.
The volcano continues to experience frequent
earthquakes, and many
fumaroles exist near the summit. The temperature of gases emitted at these fumaroles has been measured at over . In light of its proximity to Petropavlovsk-Kamchatsky, Avachinsky was designated a
Decade Volcano in 1996 as part of the
United Nations' International Decade for Natural Disaster Reduction, together with the nearby
Koryaksky volcano.
See also
*
List of volcanoes in Russia
References
External links
VolcanoWorld information
{{Decade Volcanoes
Active volcanoes
Decade Volcanoes
Volcanoes of the Kamchatka Peninsula
Mountains of the Kamchatka Peninsula
VEI-4 volcanoes
Calderas of Russia
Stratovolcanoes of Russia
Holocene stratovolcanoes
Holocene Asia
Pleistocene stratovolcanoes
