Lonquimay (volcano)

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Lonquimay
Lonquimay Volcano.jpg
Lonquimay's northwest face
Highest point
Elevation 2,865 m (9,400 ft)
Coordinates 38°22′36″S71°35′00″W / 38.37667°S 71.58333°W / -38.37667; -71.58333
Geography
Relief Map of Chile.jpg
Red triangle with thick white border.svg
Lonquimay
Parent range Andes
Geology
Mountain type Stratovolcano
Last eruption 1988 to 1990

Lonquimay Volcano is a stratovolcano of late-Pleistocene to dominantly Holocene age, with the shape of a truncated cone. The cone is largely andesitic, though basaltic and dacitic rocks are present. [1] It is located in the La Araucanía Region of Chile, immediately SE of Tolhuaca volcano. Sierra Nevada and Llaima are their neighbors to the south. The snow-capped volcano lies within the protected area Malalcahuello-Nalcas.

Stratovolcano Tall, conical volcano built up by many layers of hardened lava and other ejecta

A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava, tephra, pumice and ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and periodic intervals of explosive eruptions and effusive eruptions, although some have collapsed summit craters called calderas. The lava flowing from stratovolcanoes typically cools and hardens before spreading far, due to high viscosity. The magma forming this lava is often felsic, having high-to-intermediate levels of silica, with lesser amounts of less-viscous mafic magma. Extensive felsic lava flows are uncommon, but have travelled as far as 15 km (9.3 mi).

The Pleistocene is the geological epoch which lasted from about 2,588,000 to 11,700 years ago, spanning the world's most recent period of repeated glaciations. The end of the Pleistocene corresponds with the end of the last glacial period and also with the end of the Paleolithic age used in archaeology.

Holocene The current geological epoch, covering the last 11,700 years

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 together form the Quaternary period. The Holocene has been identified with the current warm period, known as MIS 1. It is considered by some to be an interglacial period within the Pleistocene Epoch.

Contents

The volcano's last eruption began on December 25, 1988, earning it the nickname "Navidad". [2] The eruption lasted for 13 months before ending in 1990. The Volcanic Explositivy Index was 3, indicating tropospheric injections and catastrophic damage. The eruption was from a flank vent and involved mostly andesite lava, and had been preceded by increased seismicity for three weeks. [3] The volume of the lava flow decreased as time went on and the vent dimensions decreased, though by the end of the eruption the andesite had still built up to a length of 10.2 km. [3]

Volcanic Explosivity Index qualitative scale indicating the explosive intensity of volcanic eruptions

The Volcanic Explosivity Index (VEI) is a relative measure of the explosiveness of volcanic eruptions. It was devised by Chris Newhall of the United States Geological Survey and Stephen Self at the University of Hawaii in 1982.

Troposphere The lowest layer of the atmosphere

The troposphere is the lowest layer of Earth's atmosphere, and is also where nearly all weather conditions take place. It contains approximately 75% of the atmosphere's mass and 99% of the total mass of water vapor and aerosols. The average height of the troposphere is 18 km in the tropics, 17 km in the middle latitudes, and 6 km in the polar regions in winter. The total average height of the troposphere is 13 km.

Andesite An intermediate volcanic rock

Andesite ( or ) 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 rhyolite, and ranges from 57 to 63% silicon dioxide (SiO2) as illustrated in TAS diagrams. The mineral assemblage is typically dominated by plagioclase plus pyroxene or hornblende. Magnetite, zircon, apatite, ilmenite, biotite, and garnet are common accessory minerals. Alkali feldspar may be present in minor amounts. The quartz-feldspar abundances in andesite and other volcanic rocks are illustrated in QAPF diagrams.

There was only a single fatality for the duration of the eruption, but it caused the evacuation of over 2000 people and caused extensive damage to farming and livestock in the surrounding region. [2] [4]

Research that models the internal architecture of the volcano indicate that Lonquimay has reached its maximum height and that any large eruption of lava will likely occur from flank vents and not from the summit. [5]

Lava Molten rock expelled by a volcano during an eruption

Lava is molten rock generated by geothermal energy and expelled through fractures in planetary crust or in an eruption, usually at temperatures from 700 to 1,200 °C. The structures resulting from subsequent solidification and cooling are also sometimes described as lava. The molten rock is formed in the interior of some planets, including Earth, and some of their satellites, though such material located below the crust is referred to by other terms.

Parasitic cone

A parasitic cone is the cone-shaped accumulation of volcanic material not part of the central vent of a volcano. It forms from eruptions from fractures on the flank of the volcano. These fractures occur because the flank of the volcano is unstable. Eventually, the fractures reach the magma chamber and generate eruptions called flank eruptions, which, in turn, produce a parasitic cone.

See also

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Parinacota (volcano) Volcano on the border of Chile and Bolivia

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Volcanology of Chile

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Michoacán–Guanajuato volcanic field mountain in Mexico

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Acamarachi mountain in El Loa Province Chile

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Fueguino is a volcanic field in Chile. The southernmost volcano in the Andes, it lies on Tierra del Fuego's Cook Island and also extends over nearby Londonderry Island. The field is formed by lava domes, pyroclastic cones, and a crater lake.

References

Global Volcanism Program American research program

The Smithsonian Institution's Global Volcanism Program (GVP) documents Earth's volcanoes and their eruptive history over the past 10,000 years. The GVP reports on current eruptions from around the world as well as maintaining a database repository on active volcanoes and their eruptions. In this way, a global context for the planet's active volcanism is presented. Smithsonian reporting on current volcanic activity dates back to 1968, with the Center for Short-Lived Phenomena (CSLP). The GVP is housed in the Department of Mineral Sciences, part of the National Museum of Natural History, on the National Mall in Washington, D.C.

Smithsonian Institution Group of museums and research centers administered by the United States government

The Smithsonian Institution, founded on August 10, 1846 "for the increase and diffusion of knowledge," is a group of museums and research centers administered by the Government of the United States. The institution is named after its founding donor, British scientist James Smithson. Originally organized as the "United States National Museum," that name ceased to exist as an administrative entity in 1967.

  1. "Lonquimay." Global Volcanism Program. Smithsonian Institution
  2. 1 2 "Lonquimay Volcano Eruptions". Volcano Discovery.
  3. 1 2 Sparks (1992). "Morphological, structural, and textural variations in the 1988-1990 andesite lava of Lonquimay volcano, Chile". Cambridge University Geological Magazine.
  4. Naranjo, Jose. "Lonquimay." Global Volcanism Program. Smithsonian Institution National Museum of Natural History
  5. Contreras, María Angélica; Castruccio, Ángelo (2018). El control de las propiedades del sistema magmático en las dimensiones que alcanza un edificio volcánico: Análisis de los volcanes Lascar, Lonquimay y Llaima, Andes de Chile [The control of the properties of the magmatic system in the dimensions reached by a volcanic building: Analysis of the Lascar, Lonquimay and Llaima volcanoes, Andes of Chile]. XV Congreso Geológico Chileno (in Spanish). Concepción, Chile.