Supervolcano

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

A supervolcano is any volcano capable of producing a volcanic eruption with an ejecta mass greater than 10¹⁵ kg. Supervolcanoes can occur when magma in the mantle rises into the crust from a hotspot but is unable to break through the crust, and pressure builds in a large and growing magma pool until the crust is unable to contain the pressure (this is the case for the Yellowstone Caldera). They can also form at convergent plate boundaries (for example, Toba). Large igneous provinces 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.

Terminology

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. 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. In the review, Byers refers to Mount Multnomah as a supervolcano. 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.

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". 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.

Large igneous provinces

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. 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

Main article: World's largest eruptions

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 logarithmic 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 9 Despite some claims, there are no explosive eruptions known to volcanologists that are confirmed to have attained a VEI of 9. To do so, the eruption would have to release the Dense Rock Equivalent (DRE) of at least 10,000 km³ (2,400 cu mi) of ejecta. There are no known deposits of this volume that can be attributed to any single eruption.

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

Cross-section through Long Valley Caldera.

VEI 9

The eight eruptions at the Paraná and Etendeka traps during the Cretaceous period when taken together were well over 15,000 km³, and may have been a single event that was the largest explosion during the Phanerozoic Eon, but there have been no confirmed VEI 9 eruptions.

VEI 8

This list is incomplete; you can help by expanding it.

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	US, Colorado	Fish Canyon eruption.	27,800,000	5,000 km³
Lake Toba	Lake Toba	Indonesia, Sumatra	Produced 2200-4400 tons of H2SO4.	74,000	2,800 km³
Huckleberry Ridge eruption	Yellowstone hotspot	US, Idaho/Wyoming	Huckleberry Ridge Tuff	2,100,000	2,500 km³
Atana Ignimbrite	Pacana Caldera	Chile, Northern	Part of the Altiplano–Puna volcanic complex	4,000,000	2,500 km³
Whakamaru	Taupo Volcanic Zone	New Zealand, North Island	Whakamaru Ignimbrite/Mount Curl Tephra	340,000	2,000 km³
Heise Volcanic Field	Yellowstone hotspot	US, Idaho	Kilgore Tuff	4,500,000	1,800 km³.
Heise Volcanic Field	Yellowstone hotspot	US, Idaho	Blacktail Tuff	6,000,000	1,500 km³.
Cerro Guacha	Altiplano-Puna volcanic complex	Bolivia	Guacha ignimbrite, two smaller eruptions identified	5,700,000	1,300 km³.
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	US, Wyoming	Lava Creek Tuff	640,000	1,000 km³

Based on incomplete statistics, at least 60 VEI 8 eruptions have been identified.

VEI 7

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, Taupo Volcano's Hatepe eruption, c. 232, Baekdu Mountain, in 946–47, and the eruption of Mount Samalas in 1257.

This list is incomplete; you can help by expanding it.

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
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
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
Kurile Lake	Kamchatka Peninsula	Russia	Kurile Lake 6,440 BC	10,500	140–170 km³
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
Campi Flegrei		Italy, Naples		39,000	84 km³*
Mount Aso		Japan, Kyūshū	Four large explosive eruptions between 300,000 to 80,000 years ago.	300,000	600 km³
Reporoa Caldera	Taupo Volcanic Zone	New Zealand, North Island		230,000	100 km³
Mamaku Ignimbrite	Taupo Volcanic Zone	New Zealand, North Island	Rotorua Caldera	240,000	280 km³
Matahina Ignimbrite	Taupo Volcanic Zone	New Zealand, North Island	Haroharo Caldera	280,000	120 km³
Long Valley Caldera	Bishop Tuff	USA, California		760,000	600 km³
Valles Caldera	Jemez volcanic field	USA, New Mexico	Two eruptions at 1.15 and 1.47 million years ago	1,150,000	600 km³
Mangakino	Taupo Volcanic Zone	New Zealand, North Island	Three eruptions from 0.97 to 1.23 million years ago	970,000	300 km³
Henry's Fork Caldera	Yellowstone hotspot Mesa Falls Tuff	USA, Idaho	Yellowstone hotspot	1,300,000	280 km³
Karymshina	Kamchatka	Russia		1,780,000	>1000 km³
Pastos Grandes Ignimbrite	Pastos Grandes Caldera	Bolivia		2,900,000	820 km³
Heise volcanic field	Yellowstone hotspot Walcott Tuff	USA, Idaho	Yellowstone hotspot	6,400,000	750 km³
Bruneau-Jarbidge caldera	Yellowstone hotspot	USA, Idaho	Yellowstone hotspot Responsible for the Ashfall Fossil Beds 1,600 km to the east	6,710,000	950 km³
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

* means DRE (dense rock equivalent).

Media portrayal

Satellite image of San Salvador, El Salvador and the Lake Ilopango caldera (also known as the Dark Age volcano) in the Valley of the Hammocks, site of a VEI 6-8 eruption and said to be ground zero for the extreme weather events of 535–536, when a dark veil settled on the world.

Volcano, lake, and caldera locations in the Taupo Volcanic Zone

• In 2004, Naked Science TV show aired supervolcano on National Geographic Channel.
• In 2005, a two-part television docudrama 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.
• 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 will be featured in the next volume, Long Mars.
• The Siberian Traps and Lake Toba made an appearance in Animal Planet's prehistoric documentary Animal Armageddon (each in one episode), where speculation of the lifeforms they afflicted were brought to life.

See also

• Risks to civilization, humans, and planet Earth
• Toba catastrophe theory
• Timetable of major worldwide volcanic eruptions
• Volcanic winter

External links

• Overview and Transcript of the original BBC program
• Yellowstone Supervolcano and Map of Supervolcanoes Around The World
• USGS Fact Sheet – Steam Explosions, Earthquakes, and Volcanic Eruptions – What's in Yellowstone's Future?
• Scientific American's The Secrets of Supervolcanoes
• Supervolcano eruption mystery solved, BBC Science, 6 January 2014