Asupervolcano is avolcano that has had aneruption with avolcanic explosivity index (VEI) of 8,[1] the largest recorded value on the index. This means the volume of deposits for such an eruption is greater than 1,000 cubic kilometers (240 cubic miles).[2]
Location of Yellowstone hotspot over time. Numbers indicate millions of years before the present.Satellite image ofLake Toba, the site of a VEI 8 eruption c. 75,000 years agoCross-section throughLong Valley Caldera
Supervolcanoes occur whenmagma in themantle rises into thecrust but is unable to break through it. Pressure builds in a large and growing magma pool until the crust is unable to contain the pressure and ruptures. This can occur athotspots (for example,Yellowstone Caldera) or atsubduction zones (for example,Toba).[3][4]
The term "supervolcano" was first used in a volcanic context in 1949.[6][7][note 1] Its origins lie in an early 20th-century scientific debate about the geological history and features of theThree Sisters volcanic region ofOregon in the United States. In 1925, Edwin T. Hodge suggested that a very large volcano, which he namedMount Multnomah, had existed in that region.[note 2] He believed that severalpeaks in the Three Sisters area were remnants of Mount Multnomah after it had been largely destroyed by violent volcanic explosions, similarly toMount Mazama.[9] In his 1948 bookThe Ancient Volcanoes of Oregon, volcanologistHowel Williams ignored the possible existence of Mount Multnomah, but in 1949 another volcanologist, F. M. Byers Jr., reviewed the book, and in the review, Byers refers to Mount Multnomah as a "supervolcano".[10][11]
More than fifty years after Byers' review was published, the termsupervolcano was popularised by theBBC popular science television programHorizon in 2000, referring to eruptions that produce extremely large amounts ofejecta.[12][13]
Though there is no well-defined minimum explosive size for a "supervolcano", there are at least two types of volcanic eruptions that have been identified as supervolcanoes:large igneous provinces and massive eruptions.[15]
Large igneous provinces, such asIceland, theSiberian Traps,Deccan Traps, and theOntong Java Plateau, are extensive regions ofbasalts on a continental scale resulting fromflood basalt eruptions. When created, these regions often occupy several thousand square kilometres and have volumes on the order of millions of cubic kilometers. In most cases, the lavas are normally laid down over several million years. They release large amounts of gases.
TheRéunion hotspot produced the Deccan Traps about 66 million years ago, coincident with theCretaceous–Paleogene extinction event. The scientific consensus is thatan asteroid impact was the cause of the extinction event, but the volcanic activity may have caused environmental stresses on extant species up to theCretaceous–Paleogene boundary.[16] Some scientists have hypothesised that the volcanism around the Deccan Traps could have been intensified by the Chicxulub impact, which would have been close to theantipodal point of the Traps at that time.[17]
Additionally, the largest flood basalt event (the Siberian Traps) occurred around 250 million years ago and was coincident with the largest mass extinction in history, thePermian–Triassic extinction event, although it is unknown whether it was solely responsible for the extinction event.
Such outpourings are not explosive, thoughlava fountains may occur. Many volcanologists considerIceland to be a large igneous province that is currently being formed. The last major outpouring occurred in 1783–84 from theLaki fissure, which is approximately 40 km (25 mi) long. An estimated 14 km3 (3.4 cu mi) of basaltic lava was poured out during the eruption (VEI 4).
The Ontong Java Plateau has an area of about 2,000,000 km2 (770,000 sq mi), and the province was at least 50% larger before theManihiki andHikurangi Plateaus broke away.
Volcanic eruptions are classified using thevolcanic explosivity index. It is alogarithmic scale, and an increase of one in VEI number is equivalent to a tenfold increase in volume of erupted material. VEI 7 or VEI 8 eruptions are so powerful that they often form circular calderas rather thancones because the downward withdrawal of magma causes the overlying rock mass to collapse into the emptymagma chamber beneath it.
Possibly the largest known supereruption. Existence as a single eruption is controversial, and it could have been a multiple 2,000+ km3 event that spanned less than a million years
The largest of the Indian Peak-Caliente Caldera Complex eruptions, preserved as the Wah Wah Springs Tuff; includes pyroclastic flows more than 500 meters (1,600 ft) thick
Nova featured an episode "Mystery of the Megavolcano" in September 2006 examining such eruptions in the last 100,000 years.[44]
Supervolcano is the title of a British-Canadian television disaster film, first released in 2005. It tells a fictional story of a supereruption at Yellowstone.
In the 2009 disaster film2012, a supereruption of Yellowstone is one of the events that contributes to a global cataclysm.
^The term was first used inConquering the World, a 1925 travelogue by Helen Bridgeman, referring to an Indian Ocean sunset in Indonesia as an upside down "super-volcano".[8]
^Subsequent research proved that each peak of the Three Sisters was formed independently, and that Mount Multnomah never existed.[citation needed]
^supervolcano, n. Oxford English Dictionary, third edition, online version June 2012. Retrieved on 17 August 2012.
^Byers Jr., F. M. (May 1949). "Review ofThe Ancient Volcanoes of Oregon, by H. Williams".The Journal of Geology.57 (3): 325.doi:10.1086/625620.JSTOR30058772.
^Harris, Stephen (1988).Fire Mountains of the West: The Cascade and Mono Lake Volcanoes. Missoula, Mountain Press.
^supervolcano, n. Oxford English Dictionary, third edition, online version June 2012. Retrieved on 17 August 2012.
^Byers Jr., F. M. (May 1949). "Review ofThe Ancient Volcanoes of Oregon, by H. Williams".The Journal of Geology.57 (3): 325.doi:10.1086/625620.JSTOR30058772.
^"Supervolcanoes".bbc.co.uk. BBC. 3 February 2000. Retrieved30 November 2023.
^Keller, G (2014). "Deccan volcanism, the Chicxulub impact, and the end-Cretaceous mass extinction: Coincidence? Cause and effect?".Geological Society of America Special Papers.505:57–89.doi:10.1130/2014.2505(03).ISBN978-0-8137-2505-5.
^Knight, M.D., Walker, G.P.L., Ellwood, B.B., and Diehl, J.F. (1986). "Stratigraphy, paleomagnetism, and magnetic fabric of the Toba Tuffs: Constraints on their sources and eruptive styles".Journal of Geophysical Research.91 (B10):10355–10382.Bibcode:1986JGR....9110355K.doi:10.1029/JB091iB10p10355.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^Ninkovich, D., Sparks, R.S.J., and Ledbetter, M.T. (1978). "The exceptional magnitude and intensity of the Toba eruption, Sumatra: An example of using deep-sea tephra layers as a geological tool".Bulletin Volcanologique.41 (3):286–298.Bibcode:1978BVol...41..286N.doi:10.1007/BF02597228.S2CID128626019.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^Williams, M.A.J. & Royce, K. (1982). "Quaternary geology of the middle son valley, North Central India: Implications for prehistoric archaeology".Palaeogeography, Palaeoclimatology, Palaeoecology.38 (3–4): 139.Bibcode:1982PPP....38..139W.doi:10.1016/0031-0182(82)90001-3.
^Froggatt, P. C.; Nelson, C. S.; Carter, L.; Griggs, G.; Black, K. P. (13 February 1986). "An exceptionally large late Quaternary eruption from New Zealand".Nature.319 (6054):578–582.Bibcode:1986Natur.319..578F.doi:10.1038/319578a0.S2CID4332421.The minimum total volume of tephra is 1,200 km3 but probably nearer 2,000 km3, ...
