Volcanic Explosivity Index

VEI and ejecta volume correlation

The Volcanic Explosivity Index (VEI) was devised by Chris Newhall of the U.S. Geological Survey and Steve Self at the University of Hawaiʻi in 1982 to provide a relative measure of the explosiveness of volcanic eruptions.

Volume of products, eruption cloud height, and qualitative observations (using terms ranging from "gentle" to "mega-colossal") are used to determine the explosivity value. The scale is open-ended with the largest volcanoes in history given magnitude 8. A value of 0 is given for non-explosive eruptions (less than 104 cubic metres of tephra ejected) with 8 representing a mega-colossal explosive eruption that can eject 1012 cubic metres of tephra and have a cloud column height of over 25 km (16 mi). Each interval on the scale represents a tenfold increase in observed eruption criteria.

Note that ash, volcanic bombs, and ignimbrite are all treated alike — this is due to taking into account the vesicularity (gas bubbling) of the volcanic products in question and the DRE (Dense-Rock Equivalent) is calculated to give the actual amount of magma erupted. One weakness of the VEI is that it does not take into account the magnitude of power output of an eruption. This, of course, is extremely difficult to detect with prehistoric or unobserved eruptions.

Contents

Classification

Scientists indicate how powerful volcanic eruptions are using the VEI. The VEI stands for Volcanic Explosivity Index. It records how much volcanic material is thrown out, how high the eruption goes, and how long it lasts. The scale goes from 0 to 8. An increase of 1 indicates a 10 times more powerful eruption.

Note that there is a discontinuity in the definition of the VEI between indices 1 and 2. The lower border of the volume of ejecta jumps by a factor of 100 from 10,000 to 1,000,000 m³ while the factor is 10 between all higher indices.

VEI Classification Description Plume Ejecta volume Frequency Example Occurrences *
0 Hawaiian non-explosive < 100 m < 10,000 m³ daily Mauna Loa many
1 Hawaiian/Strombolian gentle 100-1000 m > 10,000 m³ daily Stromboli many
2 Strombolian/Vulcanian explosive 1-5 km > 1,000,000 m³ weekly Galeras (1993) 3477*
3 Vulcanian/Pelean severe 3-15 km > 10,000,000 m³ yearly Koryaksky 868
4 Pelean/Plinian cataclysmic 10-25 km > 0.1 km³ ≥ 10 yrs Soufrière Hills (1995) 278
5 Plinian paroxysmal > 25 km > 1 km³ ≥ 50 yrs St. Helens (1980) 84
6 Plinian/Ultra-Plinian colossal > 25 km > 10 km³ ≥ 100 yrs Mount Pinatubo (1991) 39
7 Plinian/Ultra-Plinian super-colossal > 25 km > 100 km³ ≥ 1000 yrs Tambora (1815) 5 (+2 suspected)
8 Ultra-Plinian mega-colossal > 25 km > 1,000 km³ ≥ 10,000 yrs Toba (73,000 BP) 0

* Count of eruptions in the last 10,000 years based on 1994 figures maintained by the Global Volcanism Program of the Smithsonian Institution

A total of 47 eruptions of VEI–8 magnitude or above, ranging in age from Ordovician to Pleistocene, are identified, of which 42 eruptions are known from the past 36 million years. The most recent one is Lake Taupo's Oruanui eruption, occurring 26,500 years ago, which means that there have not been any Holocene (within the last 10,000 years) eruptions with a VEI of 8.[1]

List of eruptions

VEI Name Year
0 Mauna Loa 1984
Piton de la Fournaise 2004
Hoodoo Mountain 7050 BC?
1 Kilauea 1983 - present
Nyiragongo 2002
Wells Gray-Clearwater volcanic field 1500?
2 Mount Hood 1865-1866
Kilauea 1924
Tristan da Cunha 1961
Whakaari/White Island 2001
Mount Usu 2000-2001
3 Mount Vesuvius 1913-1944
Mount Edziza 950 AD ± 1000 years
Surtsey 1963-1967
Eldfell 1973
Nevado del Ruiz 1985
Mount Etna 2002-2003
Mount Garibaldi 9,300 BP
Nazko Cone 7,200 BP
4 Mount Pelée 1902
Parícutin 1943-1952
Hekla 1947
Galunggung 1982
Mount Spurr 1992
5 Hekla (Hekla 3 eruption) 1021 + 130/-100 BC
Mount Vesuvius (Pompeian eruption) 79
Mount Tarumae 1739
Mount Agung 1963
Mount St. Helens (1980 eruption) 1980
Mount Meager ≈400 BC (2350 BP)
El Chichón 1982
Mount Hudson 1991
Mount Tarawera 1886
6 Morne Diablotins 30,000 BP
Laacher See 12,900 BP?
Nevado de Toluca 10,500 BP
Mount Okmok 8300 BP
Mount Etna 8000 BP?
Mount Veniaminof 1750 BC
Mount Vesuvius (Avellino eruption) 1660 BC ± 43 years
Thera (Minoan eruption) 1620s BC
Mount Aniakchak ≈1645 BC
Mount Okmok 2400 BP
Mount Churchill (White River Ash) ≈750 (1200 BP)
Ilopango 450 ± 30 years
Laki 934
Baekdu Mountain (Tianchi eruption) 969 ± 20 years
Kuwae 1452 or 1453
Huaynaputina 1600
Laki 1783
Krakatoa 1883
Santa María 1902
Novarupta 1912
Mount Pinatubo 1991
7 Bennett Lake Volcanic Complex 50 Ma
Valles (Lower Bandelier eruption) 1.47 Ma
Yellowstone (Mesa Falls eruption) 1.3 Ma
Valles (Upper Bandelier eruption) 1.15 Ma
Long Valley Caldera (Bishop eruption) 759,000 BP
Manijau 280,000 BP
Atitlán (Los Chocoyos eruption) 84,000 BP
Kurile (Golygin eruption) 41,000 BP
Campi Flegrei 37,000 BP
Aira Caldera 22,000 BP
Kurile (Ilinsky eruption) 6440 BC ± 25 years
Crater Lake, Oregon (Mount Mazama eruption) 5677 BC ± 150 years
Kikai (Akahoya eruption) ≈5300 BC
Taupo (Hatepe eruption) 186
Mount Tambora 1815
8 La Garita Caldera 27 Ma
Yellowstone (Huckleberry Ridge eruption) 2.2 Ma
Galán 2.2 Ma
Yellowstone (Lava Creek eruption) 640,000 BP
Toba 73,000 BP
Taupo (Oruanui eruption) 26,500 BP

See also

Footnotes

  1. ↑ 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. doi:10.1007/s00445-004-0355-9. 

References

External links