Treffie
02-11-2009, 10:35 AM
A supervolcano or super volcanic eruption is a volcanic eruption which is substantially larger than any volcano in historic times (generally accepted to be greater than 200 cubic kilometers). This kind of eruption is typically sufficient to cause a long-lasting change to weather (such as the triggering of an ice age) sufficient to threaten the extinction of species, and cover huge areas with lava and ash.
Word origin
The term was originally used in the BBC popular science program Horizon in 2000 to refer to these types of eruptions. That programme introduced the subject of large scale eruptions to the general public.
Volcanologists and geologists do not refer to "super volcanoes" or "megacalderas" in their scientific work, but sometimes do in public presentations. However, they do describe eruptions that rate VEI 7 or 8 as "super eruptions".
Until 2003, supervolcano was not a technical term used in volcanology. 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.
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.
Supervolcanoes were seen on other planets via the Voyager program craft on the moons of Jupiter and Saturn. However, this kind of volcano on earth was not discovered until long after the Voyager had gone on to their interplanetary missions. The outer Solar System volcanoes were mostly cryovolcanoes, not magma volcanoes.
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 kilometres. 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. Research continues into the effect of the outpourings and whether they impacted upon the extinction of the dinosaurs at the end of the Cretaceous.
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 ~40 km long. An estimated 14 km3 of basaltic lava was poured out during the eruption.
The Ontong Java Plateau now has an area of about 2 million km2, and the province was at least 50% larger before the Manihiki and Hikurangi Plateaus broke away.
Massive explosive eruptions
Eruptions with a Volcanic Explosivity Index of 8 (VEI-8) are colossal events that throw out at least 1,000 km3 Dense Rock Equivalent (DRE) of ejecta; VEI-7 events eject at least 100 km3 (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) its geology and volcanic succession has recently been re-analysed in the light of new discoveries. 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 25 km3.
Known super eruptions
VEI 8 eruptions have happened in the following locations.
Lake Taupo, North Island, New Zealand - Oruanui eruption ~26,500 years ago (~1,170 km3)
http://www.geonet.org.nz/images/volcano/our-volcanoes/Lake-Taupo-28761-lge.jpg
Lake Toba, Sumatra, Indonesia - ~75,000 years ago (~2,800 km3)
http://www.wayfaring.info/images/lake_toba_indonesia_aerial.jpg
Whakamaru, North Island, New Zealand - Whakamaru Ignimbrite/Mount Curl Tephra ~254,000 years ago (1,200-2,000 km3)
http://www.climb.co.nz/Places/waikato/whakamaru/Whakamaru1.jpg
Yellowstone Caldera, Wyoming, United States - 640,000 years ago (1,000 km3)
http://blogs.tnr.com/tnr/blogs/environmentandenergy/CalderaRim2.jpg
Island Park Caldera, Idaho/Wyoming, United States - 2.1 million years ago(2,500 km3)
http://www.isu.edu/~vankrobe/henrys_fork/images/04caldera.jpg
Kilgore Tuff, Idaho, United States - 4.5 million years ago (1,800 km3)
Black Tail Creek, Idaho, United States - 6.6 million years ago (1,500 km3)
La Garita Caldera, Colorado, United States - Source of the truly enormous eruption of the Fish Canyon Tuff ~27.8 million years ago (~5,000 km3)
http://sangres.com/cimages/places/creede/creede01.jpg
The Lake Toba eruption plunged the Earth into a volcanic winter, eradicating an estimated 60% of the human population (although humans managed to survive, even in the vicinity of the volcano), and was responsible for the formation of sulfuric acid in the atmosphere.
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 AD, and possibly Baekdu Mountain, around 979 AD.
Tambora, West Nusa Tenggara, Indonesia - 1815 (160 km3)
http://www.scarborough.k12.me.us/wis/teachers/dtewhey/webquest/nature/images/tambora1.jpg
Baekdu Mountain, China/North Korea - ~969 AD (96±19 km3)
http://www.korealove.de/korealove/wp-content/uploads/2007/10/baitou_mountain_tianchi.jpg
Lake Taupo, North Island, New Zealand - Hatepe eruption ~181 C.E. (120 km3)
Kikai Caldera, Ryukyu Islands, Japan - ~6,300 years ago (~ 4,300 BC) (150 km3)
http://wpcontent.answers.com/wikipedia/commons/thumb/1/14/Santorini_Landsat.jpg/300px-Santorini_Landsat.jpg
Campi Flegrei, Naples, Italy - ~12,000 years ago (~ 10,000 BC) (Could be as much as 300 km3)
http://www.larivistadelmare.it/img/Campi%20flegrei%20plastico.jpg
Aira Caldera, Kyūshū, Japan - ~22,000 years ago (~ 20,000 BC) (~110 km3)
http://upload.wikimedia.org/wikipedia/commons/thumb/a/ac/Sakura-jima_from_space.jpg/250px-Sakura-jima_from_space.jpg
Reporoa caldera, New Zealand - 230,000 years ago (~100 km3)
http://www.tboeckel.de/EFSF/efsf_wv/newzealand_07/3c.jpg
Aso, Kyūshū, Japan - four large explosive eruptions between 300,000 to 80,000 years ago (last one > 600 km3)
http://volcano.oregonstate.edu/vwdocs/volc_images/north_asia/ML16.jpg
Long Valley Caldera, California, United States - ~760,000 years ago (600 km3)
http://www.visitusa.com/california/images/mammoth-mountain/long-valley-caldera.jpg
Valles Caldera, New Mexico, United States - ~1.12 million years ago (~600 km3)
http://pro.corbis.com/images/IH205128.jpg?size=67&uid=%7BB7CAAC2B-B65C-4328-8480-778EFD4DEA72%7D
Mangakino, North Island, New Zealand - three eruptions from 0.97 to 1.23 million years ago (each > 300 km3)
Henry's Fork Caldera, Idaho, United States - 1.3 million years ago (280 km3)
Walcott Tuff, Idaho, United States - 6.4 million years ago (750 km3)
Bennett Lake Volcanic Complex, British Columbia/Yukon, Canada - ~50 million years ago (850 km3)
http://www.cricyt.edu.ar/iai/images/poster4.jpg
Bruneau-Jarbidge, Idaho, United States - ~10-12 million years ago (>250 km3) (responsible for the Ashfall Fossil Beds ~1,600 km to the east)
http://www.americanwhitewater.org/photos/archive/medium/944.jpg
Word origin
The term was originally used in the BBC popular science program Horizon in 2000 to refer to these types of eruptions. That programme introduced the subject of large scale eruptions to the general public.
Volcanologists and geologists do not refer to "super volcanoes" or "megacalderas" in their scientific work, but sometimes do in public presentations. However, they do describe eruptions that rate VEI 7 or 8 as "super eruptions".
Until 2003, supervolcano was not a technical term used in volcanology. 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.
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.
Supervolcanoes were seen on other planets via the Voyager program craft on the moons of Jupiter and Saturn. However, this kind of volcano on earth was not discovered until long after the Voyager had gone on to their interplanetary missions. The outer Solar System volcanoes were mostly cryovolcanoes, not magma volcanoes.
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 kilometres. 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. Research continues into the effect of the outpourings and whether they impacted upon the extinction of the dinosaurs at the end of the Cretaceous.
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 ~40 km long. An estimated 14 km3 of basaltic lava was poured out during the eruption.
The Ontong Java Plateau now has an area of about 2 million km2, and the province was at least 50% larger before the Manihiki and Hikurangi Plateaus broke away.
Massive explosive eruptions
Eruptions with a Volcanic Explosivity Index of 8 (VEI-8) are colossal events that throw out at least 1,000 km3 Dense Rock Equivalent (DRE) of ejecta; VEI-7 events eject at least 100 km3 (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) its geology and volcanic succession has recently been re-analysed in the light of new discoveries. 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 25 km3.
Known super eruptions
VEI 8 eruptions have happened in the following locations.
Lake Taupo, North Island, New Zealand - Oruanui eruption ~26,500 years ago (~1,170 km3)
http://www.geonet.org.nz/images/volcano/our-volcanoes/Lake-Taupo-28761-lge.jpg
Lake Toba, Sumatra, Indonesia - ~75,000 years ago (~2,800 km3)
http://www.wayfaring.info/images/lake_toba_indonesia_aerial.jpg
Whakamaru, North Island, New Zealand - Whakamaru Ignimbrite/Mount Curl Tephra ~254,000 years ago (1,200-2,000 km3)
http://www.climb.co.nz/Places/waikato/whakamaru/Whakamaru1.jpg
Yellowstone Caldera, Wyoming, United States - 640,000 years ago (1,000 km3)
http://blogs.tnr.com/tnr/blogs/environmentandenergy/CalderaRim2.jpg
Island Park Caldera, Idaho/Wyoming, United States - 2.1 million years ago(2,500 km3)
http://www.isu.edu/~vankrobe/henrys_fork/images/04caldera.jpg
Kilgore Tuff, Idaho, United States - 4.5 million years ago (1,800 km3)
Black Tail Creek, Idaho, United States - 6.6 million years ago (1,500 km3)
La Garita Caldera, Colorado, United States - Source of the truly enormous eruption of the Fish Canyon Tuff ~27.8 million years ago (~5,000 km3)
http://sangres.com/cimages/places/creede/creede01.jpg
The Lake Toba eruption plunged the Earth into a volcanic winter, eradicating an estimated 60% of the human population (although humans managed to survive, even in the vicinity of the volcano), and was responsible for the formation of sulfuric acid in the atmosphere.
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 AD, and possibly Baekdu Mountain, around 979 AD.
Tambora, West Nusa Tenggara, Indonesia - 1815 (160 km3)
http://www.scarborough.k12.me.us/wis/teachers/dtewhey/webquest/nature/images/tambora1.jpg
Baekdu Mountain, China/North Korea - ~969 AD (96±19 km3)
http://www.korealove.de/korealove/wp-content/uploads/2007/10/baitou_mountain_tianchi.jpg
Lake Taupo, North Island, New Zealand - Hatepe eruption ~181 C.E. (120 km3)
Kikai Caldera, Ryukyu Islands, Japan - ~6,300 years ago (~ 4,300 BC) (150 km3)
http://wpcontent.answers.com/wikipedia/commons/thumb/1/14/Santorini_Landsat.jpg/300px-Santorini_Landsat.jpg
Campi Flegrei, Naples, Italy - ~12,000 years ago (~ 10,000 BC) (Could be as much as 300 km3)
http://www.larivistadelmare.it/img/Campi%20flegrei%20plastico.jpg
Aira Caldera, Kyūshū, Japan - ~22,000 years ago (~ 20,000 BC) (~110 km3)
http://upload.wikimedia.org/wikipedia/commons/thumb/a/ac/Sakura-jima_from_space.jpg/250px-Sakura-jima_from_space.jpg
Reporoa caldera, New Zealand - 230,000 years ago (~100 km3)
http://www.tboeckel.de/EFSF/efsf_wv/newzealand_07/3c.jpg
Aso, Kyūshū, Japan - four large explosive eruptions between 300,000 to 80,000 years ago (last one > 600 km3)
http://volcano.oregonstate.edu/vwdocs/volc_images/north_asia/ML16.jpg
Long Valley Caldera, California, United States - ~760,000 years ago (600 km3)
http://www.visitusa.com/california/images/mammoth-mountain/long-valley-caldera.jpg
Valles Caldera, New Mexico, United States - ~1.12 million years ago (~600 km3)
http://pro.corbis.com/images/IH205128.jpg?size=67&uid=%7BB7CAAC2B-B65C-4328-8480-778EFD4DEA72%7D
Mangakino, North Island, New Zealand - three eruptions from 0.97 to 1.23 million years ago (each > 300 km3)
Henry's Fork Caldera, Idaho, United States - 1.3 million years ago (280 km3)
Walcott Tuff, Idaho, United States - 6.4 million years ago (750 km3)
Bennett Lake Volcanic Complex, British Columbia/Yukon, Canada - ~50 million years ago (850 km3)
http://www.cricyt.edu.ar/iai/images/poster4.jpg
Bruneau-Jarbidge, Idaho, United States - ~10-12 million years ago (>250 km3) (responsible for the Ashfall Fossil Beds ~1,600 km to the east)
http://www.americanwhitewater.org/photos/archive/medium/944.jpg