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A supervolcano is any volcano capable of producing a volcanic eruption with an ejecta volume greater than 1,000 km3 (240 cu mi). This is thousands of times larger than normal volcanic eruptions.[1] 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).

Although there are only a handful of Quaternary supervolcanoes, supervolcanic eruptions typically cover huge areas with lava and volcanic ash and cause a long-lasting change to weather (such as the triggering of a small ice age) sufficient to 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, 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 volcano scientist, 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 conditions. Since 2000, however, the term has been used by professionals when presenting 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".[citation needed][7]

Though there is no well-defined minimum explosive size for a "supervolcano", there are at least two types of volcanic eruption that have been identified as supervolcanoes: large igneous provinces and massive eruptions.[citation needed]

Large igneous provinces

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.[citation needed] 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 fire 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

Volcanic eruptions are classified using the Volcanic Explosivity Index, or VEI.
VEI – 8 eruptions are colossal events that throw out at least 1,000 km3 (240 cu mi) Dense Rock Equivalent (DRE) of ejecta.

VEI – 7 events eject at least 100 cubic kilometres (24 cu mi) DRE.

VEI – 7 or 8 eruptions are so powerful that they often form circular calderas rather than cones because the downward withdrawal of magma causes the overlying mass to collapse and fill the void magma chamber beneath.

One of the classic calderas is at Glen Coe in the Grampian Mountains of Scotland. First described by Clough et al. (1909)[8] its geology and volcanic succession have recently been re-analysed in the light of new discoveries.[9] There is an accompanying 1:25000 solid geology map.

By way of comparison, the 1980 Mount St. Helens eruption was a VEI-5 with 1.2 km3 of ejecta.

Both Mount Pinatubo in 1991 and Krakatoa in 1883 were VEI-6 with 10 and 25 km3 (2.4 and 6.0 cu mi) DRE, respectively. The death toll recorded by the Dutch authorities in 1883 was 36,417, although some sources put the estimate at more than 120,000 deaths.

Known supereruptions


Cross-section through Long Valley Caldera

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

VEI 9

The Eruptions at the Paraná and Etendeka traps during the Cretaceous period when taken together are well over 15,000 km³, and may have been a single event that was the largest explosion during the Phanerozoic Eon.

VEI 8

VEI 8 eruptions have happened in the following locations.
Name Zone Location Notes Years ago (approx.) Ejecta volume (approx.) Reference
La Garita Caldera USA, Colorado Source of the Fish Canyon Tuff, may have been a VEI 9. 27,800,000 5,000 km³
Lake Toba Lake Toba Indonesia / Sumatra The disputed[10] Toba catastrophe theory (if true, could have eradicated 60% of human population) 74,000 2,800 km³ [10][11][12][13][14]
Huckleberry Ridge eruption Yellowstone Hotspot USA, Idaho / Wyoming Huckleberry Ridge Tuff 2,100,000 2,500 km³ [15]
Atana Ignimbrite Pacana Caldera Chile, Northern 4,000,000 2,500 km³ [16]
Whakamaru Taupo Volcanic Zone, New Zealand, North Island Whakamaru Ignimbrite/Mount Curl Tephra 254,000 2,000 km³ [17]
Heise Volcanic Field Yellowstone Hotspot USA, Idaho Kilgore Tuff 4,500,000 1,800 km³. [18]
Heise Volcanic Field Yellowstone Hotspot USA, Idaho Blacktail Tuff 6,000,000 1,500 km³. [18]
Lake Taupo Taupo Volcanic Zone New Zealand, North Island Oruanui eruption 26,500 1,170 km³
Cerro Galan Argentina, Catamarca Province 2,500,000 1,050 km³
Lava Creek eruption Yellowstone Hotspot USA, Wyoming Lava Creek Tuff 640,000 1,000 km³ [15]

VEI 7

VEI-7 volcanic events, less colossal but still supermassive, have occurred in the geological past. The only ones in historic times are Tambora, in 1815, Lake Taupo, Hatepe, around AD 180,[19] and possibly Baekdu Mountain, AD 969 ± 20 years[20] and the Minoan eruption of Santorini.

VEI 7 eruptions have happened in the following locations.
Name Zone Location Event / notes Years Ago (Approx.) Ejecta Volume (Approx.)
Mount Tambora Sumbawa Island, West Nusa Tenggara Indonesia This eruption took place in 1815. The following year, 1816, became known as the Year Without a Summer. 199 160 km³
Mysterious 1809 Mega-eruption Colombia South America This eruption took place in December 1808. The following years, 1810-1811, affected the climate with severe global cooling. It was surprisingly unnoticed until the 1990s. 206 80 km³
Baekdu Mountain China / North Korea AD 969 Baekdu Mountain. Ejecta ±19 1,030 96 km³
Lake Taupo Taupo Volcanic Zone New Zealand, North Island Hatepe eruption AD 181 1,800 120 km³
[19]
Thera South Aegean Volcanic Arc Santorini, Greece Minoan eruption ca. 1610 BC 3,600 60 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
[21][22]
Kurile Lake Kamchatka Peninsula Russia Kurile Lake
6,440 BC		 10,500 .
Aira Caldera Japan, Kyūshū Aira Caldera 22,000 110 km³
Rotoiti Ignimbrite Taupo Volcanic Zone New Zealand, North Island Rotoiti Ignimbrite 50,000 240 km³
[23]
Campi Flegrei Italy, Naples 39,280 500 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
[24]
Mamaku Ignimbrite Taupo Volcanic Zone New Zealand, North Island Rotorua Caldera 240,000 280 km³
[25]
Matahina Ignimbrite Taupo Volcanic Zone New Zealand, North Island Haroharo Caldera 280,000 120 km³
[26]
Long Valley Caldera Bishop Tuff USA, California 760,000 600 km³
Valles Caldera USA, New Mexico Two eruptions at 1.15 and 1.47 million years ago 1,150,000
[27]		 600 km³
[27]
Mangakino Taupo Volcanic Zone New Zealand, North Island Three eruptions from 0.97 to 1.23 million years ago 970,000 300 km³
[28]
Henry's Fork Caldera Yellowstone Hotspot
Mesa Falls Tuff		 USA, Idaho Yellowstone Hotspot 1,300,000 280 km³
[15]
Karymshina Kamchatka Russia 1,780,000
[29]		 .
Pastos Grandes Ignimbrite Pastos Grandes Caldera Bolivia 2,900,000 820 km³
[30]
Heise volcanic field Yellowstone Hotspot
Walcott Tuff		 USA, Idaho Yellowstone Hotspot 6,400,000 750 km³
[18]
Bruneau-Jarbidge Yellowstone Hotspot USA, Idaho Yellowstone Hotspot
Responsible for the Ashfall Fossil Beds 1,600 km to the east[31]		 12,000,000 250 km³
Bennett Lake Volcanic Complex Skukum Group Canada, British Columbia/Yukon 50,000,000 850 km³
[32]

Ongoing studies

Media portrayal


Satellite image of San Salvador City and Lake Ilopango caldera aka (Dark Age Volcano) in the valley of the hammocks, site of a VEI 6-8 eruption, said to be ground zero for the infamous extreme weather events of 535–536 when a dark veil settled on the world. El Salvador, Central America.

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

Volcano, lake, and caldera locations in the Taupo Volcanic Zone
  • In 2004, Naked Science TV show aired supervolcano on National Geographic Channel.
  • Nova featured an episode "Mystery of the Megavolcano" in September 2006 examining such eruptions in the last 100,000 years.[36]
  • 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 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. The last volume Supervolcano: Maelstrom is scheduled for 2014.