A supervolcano is a volcano capable of producing a volcanic eruption with an ejecta volume greater than 1,000 cubic kilometers (240 cubic miles). This is thousands of times larger than most historic volcanic eruptions.^[1] Supervolcanoes can occur when magma in the Earth rises into the crust from a hotspot but is unable to break through the crust. Pressure builds in a large and growing magma pool until the crust is unable to contain the pressure. They can also form at convergent plate boundaries (for example, Toba) and continental hotspot locations (for example, Yellowstone).

The Discovery Channel highlighted six known supervolcanoes:^[2]

• Yellowstone,
• Long Valley, and
• Valles Caldera in the United States;
• Lake Toba, North Sumatra, Indonesia;
• Taupo Volcano, North Island, New Zealand; and
• Aira Caldera, Kagoshima Prefecture, Kyūshū, Japan.

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[link]

The term "supervolcano" was originally used in the BBC popular science television program Horizon in 2000 to refer to eruptions of this type.^[3][4] That program introduced the subject of large-scale volcanic eruptions to the general public.

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 geothermal conditions. Since 2003, however, the term has been used by professionals when presenting to the public. The term megacaldera is sometimes used for calderas with supervolcano characteristics, 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 eruption that have been identified as supervolcanoes: large igneous provinces and massive eruptions.

Large igneous provinces[link]

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 do release massive amounts of gases. The Réunion hotspot produced the Deccan Traps about 65 million years ago, coincident with the Cretaceous–Paleogene extinction event. The scientific consensus is that an astrobleme 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 Ma 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[link]

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)^[5] its geology and volcanic succession have recently been re-analysed in the light of new discoveries.^[6] There is an accompanying 1:25000 solid geology map.

By way of comparison, the 1980 Mount St. Helens eruption was at the lower end of VEI-5 with 1.2 km³, and both Mount Pinatubo in 1991 and Krakatoa in 1883 were VEI-6 with 10 km³ (2.4 cu mi) and 25 km³ (6.0 cu mi) DRE, respectively.

Known super eruptions[link]

Location of Yellowstone Hotspot in Millions of Years Ago

Estimates of the volume of ejected material are given in parentheses.

VEI 8[link]

VEI 8 eruptions have happened in the following locations.

• Lake Taupo, Taupo Volcanic Zone, North Island, New Zealand—Oruanui eruption ~26,500 years ago (~1,170 km³)
• Lake Toba, Sumatra, Indonesia—~74,000 years ago (~2,800 km³)
• Whakamaru, Taupo Volcanic Zone, North Island, New Zealand—Whakamaru Ignimbrite/Mount Curl Tephra ~254,000 years ago (1,200–2,000 km³)^[7]
• Yellowstone Caldera, Lava Creek Tuff, Wyoming, United States, Yellowstone hotspot—640,000 years ago (1,000 km³)^[8]
• Island Park Caldera, Huckleberry Ridge Tuff, Idaho/Wyoming, United States, Yellowstone hotspot—2.1 million years ago (2,500 km³)^[8]
• Cerro Galan, Catamarca Province, Argentina—2.5 million years ago (1,050 km³)
• Atana Ignimbrite, Pacana Caldera, northern Chile—4 million years ago (2,500 km³)^[9]
• Heise volcanic field, Kilgore Tuff, Idaho, United States, Yellowstone hotspot—4.5 million years ago (1,800 km³).^[10]
• Heise volcanic field, Blacktail Tuff, Idaho, United States, Yellowstone hotspot—6.6 million years ago (1,500 km³).^[10]
• La Garita Caldera, Colorado, United States—Source of the enormous eruption of the Fish Canyon Tuff ~27.8 million years ago (~5,000 km³)

The Lake Toba eruption plunged the Earth into a volcanic winter, which was claimed to have eradicated 60%^{[11][12][13][14]} of the human population, though humans managed to survive even in the vicinity of the volcano^[15] and the theory is disputed.

VEI 7[link]

Cross-section through Long Valley Caldera

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 180 CE,^[16] and possibly Baekdu Mountain, 969 CE (± 20 years).^[17]

• Tambora, Sumbawa Island, West Nusa Tenggara, Indonesia—1815 (160 km³), the following year, 1816, became known as the "Year Without a Summer"
• Baekdu Mountain, China/North Korea—~969 CE (96±19 km³)
• Lake Taupo, Taupo Volcanic Zone, North Island, New Zealand—Hatepe eruption ~181 CE (120 km³)^[16]
• Kikai Caldera, Ryukyu Islands, Japan—~6,300 years ago (~4,300 BCE) (150 km³)
• Macauley Island, Kermadec Islands, New Zealand—~6,300 years ago (~4,300 BCE) (100 km³)^[18][19]
• Kurile Lake, Kamchatka Peninsula, Russia -~8440 years ago (~6440 BCE) Kurile Lake
• Aira Caldera, Kyūshū, Japan—~22,000 years ago (~110 km³)
• Rotoiti Ignimbrite, Taupo Volcanic Zone, North Island, New Zealand—~50,000 years ago (~240 km³)^[20]
• Campi Flegrei, Naples, Italy—39,280 ± 110 years ago (500 km³)
• Aso, Kyūshū, Japan—four large explosive eruptions between 300,000 to 80,000 years ago (last one >600 km³)
• Reporoa Caldera, Taupo Volcanic Zone, North Island, New Zealand—230,000 years ago (~100 km³)^[21]
• Mamaku Ignimbrite, Rotorua Caldera, Taupo Volcanic Zone, North Island, New Zealand—240,000 years ago (>280 km³)^[22]
• Matahina Ignimbrite, Haroharo Caldera, Taupo Volcanic Zone, North Island, New Zealand—280,000 years ago (~120 km³)^[23]
• Long Valley Caldera, Bishop Tuff, California, United States—~760,000 years ago (600 km³)
• Valles Caldera, New Mexico, United States—~1.15 million years ago (~600 km³)^[24]
• Mangakino, Taupo Volcanic Zone, North Island, New Zealand—three eruptions from 0.97 to 1.23 million years ago (each > 300 km³)^[25]
• Henry's Fork Caldera, Mesa Falls Tuff, Idaho, United States, Yellowstone hotspot—1.3 million years ago (280 km³)^[8]
• Karymshina, Kamchatka, Russia—1.78±0.02 million years ago^[26]
• Pastos Grandes Ignimbrite, Pastos Grandes Caldera—2.9 million years ago (>820 km³)^[27]
• Heise volcanic field, Walcott Tuff, Idaho, United States, Yellowstone hotspot—6.4 million years ago (750 km³).^[10]
• Bruneau-Jarbidge, Idaho, United States, Yellowstone hotspot—~10–12 million years ago (>250 km³) (responsible for the Ashfall Fossil Beds ~1,600 km to the east^[28])
• Bennett Lake Volcanic Complex, British Columbia/Yukon, Canada—~50 million years ago (850 km³)^[29]

Ongoing studies[link]

• A Campanian ignimbrite super-eruption around 40,000 years ago has been hypothesised as having contributed to the demise of the Neanderthal, based on evidence from Mezmaiskaya cave in the Caucasus Mountains of southern Russia.^[30]

Media Portrayal[link]

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 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.^[31]

• 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".

• In the episode "Humanity" of 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 eruption of a massive supervolcano inside Yellowstone National Park, a result of the Earth's core heating up. This made the entirety of Southern USA uninhabitable.

See also[link]

Volcanoes portal

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

References[link]

Further reading[link]

• Mason, Ben G.; Pyle, David M.; Oppenheimer, Clive (2004). "The size and frequency of the largest explosive eruptions on Earth". Bulletin of Volcanology 66 (8): 735–748. Bibcode 2004BVol...66..735M. DOI:10.1007/s00445-004-0355-9. 
• Timmreck, C.; Graf, H.-F. (2006). "The initial dispersal and radiative forcing of a Northern Hemisphere mid-latitude super volcano: a model study". Atmospheric Chemistry and Physics 6: 35–49. DOI:10.5194/acp-6-35-2006. http://www.atmos-chem-phys.net/6/35/2006/acp-6-35-2006.html. 

External links[link]

• 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?
• Discovery Channel's site on "Supervolcano"
• Scientific American's The Secrets of Supervolcanoes
• Supervolcano at the Internet Movie Database