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The 1980 eruption of Mount St. Helens in Washington, which ripped apart the volcano's summit, was a Plinian eruption of Volcanic Explosivity Index (VEI) 5. [ 3 ] The strongest types of eruptions, with a VEI of 8, are so-called "Ultra-Plinian" eruptions, such as the one at Lake Toba 74 thousand years ago, which put out 2800 times the material ...
Augustine Volcano (Alaska) during its eruptive phase on January 24, 2006. A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. The process that forms volcanoes is called volcanism.
On Earth, volcanoes are most often found where tectonic plates are diverging or converging, and because most of Earth's plate boundaries are underwater, most volcanoes are found underwater. For example, a mid-ocean ridge , such as the Mid-Atlantic Ridge , has volcanoes caused by divergent tectonic plates whereas the Pacific Ring of Fire has ...
5 Indonesia: 1586 [2] 6,000 Santa María: 6 Guatemala: 1902 1902 eruption of Santa María [3] 5,160 Kelud: 4 Indonesia: 1919 [2] 4,011 Mount Galunggung: 5 Indonesia: 1822 [4] 3,360 Mount Vesuvius: 5 Italy: 1631 1631 eruption of Mount Vesuvius: 3,000 Ritter Island: 2 Papua New Guinea: 1888 1888 Ritter Island eruption and tsunami: 2,957 Mount ...
Supervolcano – Volcano that has had an eruption with a volcanic explosivity index (VEI) of 8; Decade Volcanoes – Set of sixteen volcanoes noted for their eruptive history and proximity to densely populated areas; Dispersal index – Indicator of spread of volcanic ejecta; Lists of volcanoes; List of natural disasters by death toll
Twelve volcanoes in the arc are over 10,000 feet (3,000 m) in elevation, and the two highest, Mount Rainier and Mount Shasta, exceed 14,000 feet (4,300 m). By volume, the two largest Cascade volcanoes are the broad shields of Medicine Lake Volcano and Newberry Volcano, which are about 145 and 108 cubic miles (600 and 450 km 3) respectively.
Compositional analysis has been very successful in the grouping of volcanoes by type, [9]: 274 origin of magma, [9]: 274 including matching of volcanoes to a mantle plume of a particular hotspot, mantle plume melting depths, [10] the history of recycled subducted crust, [9]: 302–3 matching of tephra deposits to each other and to volcanoes of ...
Volcanoes are usually mountains (sometimes islands, lakes, plateaus, calderas, seamounts or lava domes) that are formed when magma (liquid rock) wells up from inside the Earth. There are also analogous formations away from the Earth. Many volcanoes are categorized both as volcanoes and other landforms, such as mountains (if qualified).