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A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. [1] 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 ...
Ollagüe (Spanish pronunciation: [oˈʎaɣwe]) or Ullawi (Aymara: [uˈʎawi]) is a massive andesite stratovolcano in the Andes on the border between Bolivia and Chile, within the Antofagasta Region of Chile and the Potosi Department of Bolivia. Part of the Central Volcanic Zone of the Andes, its highest summit is 5,868 metres (19,252 ft) above ...
Magma rose through the edifice and expelled part of the hydrothermal system, [151] causing initial phreatic eruptions. [152] Tephra rained down around the edifice, [153] with pumice falling 25 kilometres (16 mi) from the volcano. [140] Owing to magma mixing, the pumice deposits have an appearance resembling chocolate and vanilla swirls. [100]
Mount St. Helens. Mount St. Helens (known as Lawetlat'la to the indigenous Cowlitz people, and Loowit or Louwala-Clough to the Klickitat) is an active stratovolcano located in Skamania County, Washington, [1] in the Pacific Northwest region of the United States. It lies 52 miles (83 km) northeast of Portland, Oregon, [2] and 98 miles (158 km ...
Bárðarbunga is a subglacial stratovolcano and central volcano [3] under the ice cap of Vatnajökull glacier in the Vatnajökull National Park in Iceland. It is one of the six volcanic systems under Vatnajökull. [1] The central volcano has a rim that rises to about 2,000 m (6,600 ft) above sea level, [a] making it the second highest mountain ...
Phreatic eruption at the summit of Mount St. Helens, Washington, in the spring of 1980. A phreatic eruption, also called a phreatic explosion, ultravulcanian eruption or steam-blast eruption, [1] occurs when magma heats ground water or surface water. The extreme temperature of the magma (anywhere from 500 to 1,170 °C (930 to 2,100 °F)) causes ...
A magma chamber is a large pool of liquid rock beneath the surface of the Earth. The molten rock, or magma, in such a chamber is less dense than the surrounding country rock, which produces buoyant forces on the magma that tend to drive it upwards. [1] If the magma finds a path to the surface, then the result will be a volcanic eruption ...
Lascar is a stratovolcano in Chile within the Central Volcanic Zone of the Andes, a volcanic arc that spans Peru, Bolivia, Argentina and Chile. It is the most active volcano in the region, with records of eruptions going back to 1848. It is composed of two separate cones with several summit craters.