Supervolcano

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For the 2005 disaster television film, see Supervolcano (film).
 

Map of known supervolcanoes around the world:

A supervolcano is a volcano capable of producing a volcanic eruption with an ejecta mass greater than 1015 kg (1012 t).[1] Supervolcanoes occur when magma in the mantle rises into the crust but is unable to break through it and pressure builds in a large and growing magma pool until the crust is unable to contain the pressure. This can occur at hotspots (for example, Yellowstone Caldera) or at subduction zones (for example, Toba). Another setting for the eruption of very large amounts of volcanic material is in large igneous provinces, which can cover huge areas with lava and volcanic ash, causing long-lasting climate change (such as the triggering of a small ice age or global warming), which can threaten species with extinction. The Oruanui eruption of New Zealand's Taupo Volcano, the world's most recent supereruption, had a Volcanic Explosivity Index of 8.

Terminology[edit]

The origin of the term supervolcano is linked to an early 20th-century scientific debate about the geological history and features of the Three Sisters volcanic region of Oregon in the United States. In 1925, Edwin T. Hodge suggested that a very large volcano, which he named Mount Multnomah, had existed in that region. He believed that several peaks in the Three Sisters area are the remnants left after Mount Multnomah had been largely destroyed by violent volcanic explosions, similar to Mount Mazama.[2] In 1948, the possible existence of Mount Multnomah was ignored by volcanologist Howel Williams in his book The Ancient Volcanoes of Oregon. The book was reviewed in 1949 by another volcanologist, F. M. Byers Jr.[3] In the review, Byers refers to Mount Multnomah as a supervolcano.[4] Although Hodge's suggestion that Mount Multnomah is a supervolcano was rejected long ago, the term supervolcano was popularised by the BBC popular science television program Horizon in 2000 to refer to eruptions that produce extremely large amounts of ejecta.[5][6]

Volcanologists and geologists do not refer to "supervolcanoes" in their scientific work, since this is a blanket term that can be applied to a number of different geological settings. Since about 2000, however, the term has been used by professionals for communicating science to the public. The term megacaldera is sometimes used for caldera supervolcanoes, such as the Blake River Megacaldera Complex in the Abitibi greenstone belt of Ontario and Quebec, Canada. Eruptions that rate VEI 8 are termed super eruptions.[7] 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.[1]

Large igneous provinces[edit]

Main article: Large igneous province

Large igneous provinces (LIP) such as Iceland, the Siberian Traps, Deccan Traps, and the Ontong Java Plateau are extensive regions of basalts on a continental scale resulting from flood 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. The Réunion hotspot produced the Deccan Traps about 66 million years ago, coincident with the Cretaceous–Paleogene extinction event. The scientific consensus is that a meteor impact was the cause of the extinction event, but the volcanic activity may have caused environmental stresses on extant species up to the Cretaceous–Paleogene boundary.[8]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, the Permian–Triassic extinction event, although it is also unknown whether it was completely responsible for the extinction event.

Such outpourings are not explosive, though lava fountains may occur. Many volcanologists consider that Iceland may be a LIP that is currently being formed. The last major outpouring occurred in 1783–84 from the Laki 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.

The Ontong Java Plateau now has an area of about 2,000,000 km2 (770,000 sq mi), and the province was at least 50% larger before the Manihiki and Hikurangi Plateaus broke away.

Massive explosive eruptions[edit]

 
 

Location of Yellowstone hotspot over time (numbers indicate millions of years before the present).

Volcanic eruptions are classified using the Volcanic Explosivity Index, or VEI. It is a logarithmi scale, which means that 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 than cones because the downward withdrawal of magma causes the overlying rock mass to collapse into the empty magma chamber beneath it.

VEI 8 eruptions are colossal events that throw out at least 1,000 km3 (240 cu mi) bulk volume.

 
 

Satellite image of Lake Toba, the site of a VEI 8 eruption ~75,000 years ago.

VEI 7 events eject bulk volume at least 100 km3 (24 cu mi).

VEI 6 eruptions occurred at Krakatoa in 1883 and Mount Pinatubo in 1991. These eruptions ejected ~10 and 25 km3 (2.4 and 6.0 cu mi) bulk volume, respectively. At Krakatoa, the Dutch colonial authorities claimed that the death toll was 36,417, but other estimates consider that the death toll is in excess of 120,000.

The 1980 Mount St. Helens eruption was a VEI 5 eruption, with 1.2 km3 (0.29 cu mi) bulk volume of ejecta.

Known supereruptions[edi

Cross-section through Long Valley Caldera.

VEI 8[edit]

VEI 8 eruptions have happened in the following locations.
Name Zone Location Notes Years ago (approx.) Ejecta bulk volume (approx.) Reference
La Garita Caldera San Juan volcanic field U.S., Colorado Fish Canyon eruption. 27,800,000 5,000 km3  
Lake Toba Lake Toba, North Sumatra Indonesia, Sumatra Produced 2200–4400 tons of H2SO4. 74,000 2,800 km3 [9][10][11][12][13]
Huckleberry Ridge eruption Yellowstone hotspot U.S., Idaho/Wyoming Huckleberry Ridge Tuff 2,100,000 2,500 km3 [14]
Atana Ignimbrite Pacana Caldera Chile, Northern Part of the Altiplano–Puna volcanic complex 4,000,000 2,500 km3 [15]
Whakamaru Taupo Volcanic Zone New Zealand, North Island Whakamaru Ignimbrite/Mount Curl Tephra 340,000 2,000 km3 [16]
Heise Volcanic Field Yellowstone hotspot U.S., Idaho Kilgore Tuff 4,500,000 1,800 km3. [17]
Heise Volcanic Field Yellowstone hotspot U.S., Idaho Blacktail Tuff 6,000,000 1,500 km3. [17]
Cerro Guacha Altiplano-Puna volcanic complex Bolivia Guacha ignimbrite, two smaller eruptions identified 5,700,000 1,300 km3. [18]
Oruanui eruption Taupo Volcanic Zone New Zealand, North Island Taupo Volcano (Lake Taupo) 26,500 1,170 km3  
Cerro Galán Andes Central Volcanic Zone Argentina, Catamarca Province   2,500,000 1,050 km3  
Lava Creek eruption Yellowstone hotspot U.S., Wyoming Lava Creek Tuff 640,000 1,000 km3 [14]

Based on incomplete statistics, at least 60 VEI 8 eruptions have been identified.[1][19]

VEI 7[edit]

VEI 7 eruptions, less colossal but still supermassive, have occurred in historical times. The only ones in the past 2,000 years are Tambora, in 1815,[20] Taupo Volcano's Hatepe eruption, c. 232,[21] Baekdu Mountain, in 946–47,[22] and the eruption of Mount Samalas in 1257.[23]

VEI 7 eruptions have happened in the following locations.
Name Zone Location Event / notes Years ago prior to 1950 (Approx.) Ejecta volume (Approx.)
Mount Tambora Sumbawa Island, West Nusa Tenggara Indonesia This eruption took place in 1815. 1816 became known as the Year Without a Summer. 135 120 km3
Lake Maninjau Lake Maninjau, West Sumatra Indonesia   52,000 220–250 km³
Mount Rinjani Lombok Island, West Nusa Tenggara Indonesia Possible trigger of the Little Ice Age. 703 >10 km3
Baekdu Mountain Control by Baikal Rift Zone China/North Korea One of the largest volcanic eruptions in the past 2000 years. Millennium Eruption. 1,004 100–120 km3
Taupo Volcano (Lake Taupo) Taupo Volcanic Zone New Zealand, North Island Hatepe eruption AD 232 1,718 120 km3
[21]
Kikai Caldera   Japan, Ryukyu Islands Kikai Caldera
4,300 BC
6,300 150 km3
Macauley Island Kermadec Islands New Zealand Macauley Island 8,300 to 6,300 years ago 6,300 100 km3
[24][25]
Kurile Lake Kamchatka Peninsula Russia Kurile Lake
6,440 BC
10,500 140–170 km3
[26]
Aira Caldera   Japan, Kyūshū Aira Caldera 22,000 450 km3
Rotoiti Ignimbrite Taupo Volcanic Zone New Zealand, North Island Rotoiti Ignimbrite 50,000 240 km3
[27]
Campanian Ignimbrite eruption Campi Flegrei (Phlegraean Fields) Italy, Naples   39,280 300 km3*
Mount Aso   Japan, Kyūshū Four large explosive eruptions between 300,000 and 80,000 years ago. 300,000 600 km3
Reporoa Caldera Taupo Volcanic Zone New Zealand, North Island   230,000 100 km3
[28]
Mamaku Ignimbrite Taupo Volcanic Zone New Zealand, North Island Rotorua Caldera 240,000 280 km3
[29]
Matahina Ignimbrite Taupo Volcanic Zone New Zealand, North Island Haroharo Caldera 280,000 120 km3
[30]
Long Valley Caldera Bishop Tuff U.S., California   760,000 600 km3
Valles Caldera Jemez volcanic field U.S., New Mexico Two eruptions at 1.25 and 1.61 million years ago 1,250,000
[31]
600 km3
[32]
Mangakino Taupo Volcanic Zone New Zealand, North Island Three eruptions from 0.97 to 1.23 million years ago 970,000 300 km3
[33]
Henry's Fork Caldera Yellowstone hotspot
Mesa Falls Tuff
U.S., Idaho Yellowstone hotspot 1,300,000 280 km3
[14]
Karymshina Kamchatka Russia   1,780,000
[34]
>1000 km3
[35]
Pastos Grandes Ignimbrite Pastos Grandes Caldera Bolivia   2,900,000 820 km3
[36]
Heise volcanic field Yellowstone hotspot
Walcott Tuff
U.S., Idaho Yellowstone hotspot 6,400,000 750 km3
[17]
Bruneau-Jarbidge caldera Yellowstone hotspot U.S., Idaho Yellowstone hotspot
Responsible for the Ashfall Fossil Beds 1,600 km to the east[37]
6,710,000[38] 950 km3
[39]
Cerro Panizos Altiplano-Puna volcanic complex Argentina, Bolivia   12,000,000 250 km3
Bennett Lake Volcanic Complex Skukum Group Canada, British Columbia/Yukon   50,000,000 850 km3
[40]

* means DRE (dense rock equivalent).

Media portrayal[edit]

  • In 2004, Naked Science TV show aired supervolcano on National Geographic Channel.
  • In 2005, a two-part television disaster film called Supervolcano aired on BBC One, the Discovery Channel, and other television networks worldwide.
  • Nova featured an episode Mystery of the Megavolcano in September 2006 examining such eruptions in the last 100,000 years.[41]
  • In 2006, the Sci Fi Channel aired the documentary Countdown to Doomsday which featured a segment called "Supervolcano". The same year, ABC News aired the documentary Last Days on Earth, which featured a segment called "Supervolcano".
  • Also in 2006, the Syfy Channel series Stargate Atlantis episode entitled "Inferno" featured a supervolcano as the major plot device. Dr. Rodney McKay, one of the main characters, uses Yellowstone National Park to describe what a supervolcano is.
  • In the episode "Humanity" of the television drama Young Justice, the team must relieve the pressure of the Yellowstone Caldera supervolcano caused by Red Volcano before an eruption with the potential for mass extinction takes place.
  • In 2009, the apocalypse-themed film 2012 featured the super-eruption of the massive Yellowstone Caldera, a result of the Earth's core heating up. This made most of the United States uninhabitable.
  • In 2010, the SyFy series Warehouse 13 featured an episode entitled Reset in which a supervolcano, specifically the Yellowstone Caldera, plays an important role.
  • In December 2011, author Harry Turtledove published Supervolcano: Eruption, the first of a planned four-novel series about events leading up to and following a fictional eruption of the Yellowstone Caldera. The second book in the series, Supervolcano: All Fall Down, was published in December 2012. The third book Supervolcano: Things Fall Apart, was published in December 2013.
  • At the end of Terry Pratchett and Stephen Baxter's novel Long War the Yellowstone Caldera erupts. The aftermath is featured in the next volume, Long Mars.
  • The Siberian Traps and Lake Toba were featured in Animal Planet's prehistoric documentary Animal Armageddon (each in one episode), where speculation of the lifeforms they afflicted were brought to life.