Supervolcano

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For the docudrama, see Supervolcano (documentary)

A supervolcano refers to a volcano that produces the largest and most voluminous kinds of eruption on Earth. The actual explosivity of these eruptions varies, but the sheer volume of extruded magma is enough to radically alter the landscape and severely impact global climate for years, with a cataclysmic effect on life.

The term was originally coined by the producers of the BBC popular science program, Horizon, in 2000 to refer to these types of eruption. That investigation brought the subject more into the public eye, leading to further studies of the possible effects. At first, supervolcano was not a technical term used in volcanology, but more recently, in 2003 and 2004, the term has been used in articles. Though there is no well-defined minimum size for a "supervolcano", there are at least two types of volcanic eruption that have been identified as supervolcanoes: massive eruptions and large igneous provinces.

Contents

1 Large igneous provinces
2 Massive eruptions
3 Known eruptions
4 Media portrayal
5 See also
6 References
7 External links

Large igneous provinces

A large igneous province (LIP) is an extensive region of basalts on a continental scale, resulting from flood basalt eruptions. When created, these regions often occupy several million km² and have volumes on the order of 1 million km³. In most cases, the majority of this is laid down over an extended but geologically sudden period of less than 1 million years.

Massive eruptions

Eruptions with a Volcanic Explosivity Index of 8 (VEI-8) are mega-colossal events that extrude at least 1000 km³ of magma and pyroclastic material. Such an eruption would erase virtually all life within a radius of hundreds of kilometers from the site, and entire continental regions further out can be buried meters deep in ash. VEI-8 eruptions are so powerful that they form circular calderas rather than mountains because the downward collapse of land at the eruption site fills emptied space in the magma chamber beneath. The caldera can remain for millions of years after all volcanic activity at the site has ceased.

Known eruptions

Only one VEI-9 event is known:

La Garita Caldera, Colorado, United States - 27.8 million years ago (18,000 km³)

VEI-8 volcanic events have included eruptions at the following locations (with estimates of the volume of erupted material at the event):

Lake Taupo, North Island, New Zealand - 26,500 years ago (1,170 km³)
Lake Toba, Sumatra, Indonesia - 75,000 years ago (2,800 km³)
Yellowstone Caldera, Wyoming, United States - 2.2 million years ago (2,500 km³) and 640,000 years ago (1,000 km³)
Bruneau-Jarbidge, Idaho, United States - 10-12 million years ago (responsible for the Ashfall Fossil Beds 1,600 km to the east)

The two most recent VEI-8 eruptions were at Lake Taupo, New Zealand and Lake Toba, Sumatra, and occurred around 26,500 and 75,000 years ago. The Lake Toba eruption plunged the Earth into a volcanic winter, eradicating 60% of the human population, and was responsible for the formation of sulfuric acid in the atmosphere and the Millenial Ice Age.

The largest known explosive eruption on Earth occurred at the La Garita Caldera in the San Juan Mountains in southwestern Colorado approximately 28 million years ago. This is known as the Colorado Eruption.

Many other supermassive eruptions have also occurred in the geological past, although these listed below measure at 6-7 on the VEI scale, but they were still even larger than Tambora's eruption in 1815, which was the largest known in recorded history.

Aira Caldera, Kyūshū, Japan - 22,000 years ago (110 km³)
Aso, Kyūshū, Japan - four large explosive eruptions between 300,000 to 80,000 years ago (Total volume 600 km³)
Campi Flegrei, Campania, Italy - 35,000 years ago (80 km³)
Kikai Caldera, Ryūkyū Islands, Japan - 6,300 years ago (150 km³ (bulk volume))
Lake Taupo, North Island, New Zealand - 181 AD (100 km³)
Long Valley Caldera, California, United States - 760,000 years ago (600 km³)
Valle Grande, New Mexico, United States - 1.12 million years ago (~600 km³)

For large igneous province eruptions, see that article.

Media portrayal

A two-part television docudrama entitled Supervolcano was shown on BBC, the Discovery Channel, and other TV networks worldwide. It looked at the events that would take place if the Yellowstone supervolcano (the largest supervolcano on Earth according to the program) erupted. It featured footage of volcano eruptions from around the world and computer-generated imagery depicting the event. According to the program, the eruption would have devastating effect across the globe and would cover virtually all of the United States with at least 1 cm of volcanic ash, causing mass destruction in the nearby vicinity and killing plants and wildlife across the continent. The showings were followed by Supervolcano: The Truth About Yellowstone, a documentary about the evidence behind the movie. The program had originally been scheduled to be aired in early 2005, but it was felt that this would be insensitive so soon after the real-life tragedy of the 2004 Indian Ocean earthquake. The program and its accompanying documentaries were released on DVD region 2 simultaneously with its broadcast. A National Geographic documentary called 'Earth Shocks' showed the destructive impact of the Rapid - 14 day eruption of Lake Toba some 75,000 years ago and caused a phenomenon known as the Millenial Ice Age, an ice age that lasted for 1000 years and wiped out more than 60% of the global population of the time.

References

External links

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