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'''Co-promotion''' is a [[marketing]] practice where a [[company]] in addition to its own, uses another company's [[sales force]] to promote the same [[brand]] or range of brands. The term is frequently confused with [[Co-marketing]].
[[Image:VEIfigure.jpg|thumb|270px|VEI and ejecta volume correlation]]
The '''Volcanic Explosivity Index''' (VEI) was devised by [[Chris Newhall]] of the [[U.S. Geological Survey]] and [[Steve Self (geologist)|Steve Self]] at the [[University of Hawaii]] in [[1982]] to provide a relative measure of the explosiveness of [[volcano|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 and ranges from 0, for non-explosive eruptions (less than 10<sup>4</sup> cubic metres of [[tephra]] ejected) to 8, for mega-colossal explosive eruptions that can eject 10<sup>12</sup> cubic metres of [[tephra]] and have a cloud column height of over 25 km. Each interval on the scale represents a ten-fold increase in observed eruption criteria.
== See also ==
Note that [[Volcanic ash|ash]], [[volcanic bomb]]s, and [[ignimbrite]] are all treated alike — this is due to taking into account of 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. But one weakness is that the VEI does not take into account the magnitude of power output of an eruption. However, this is extremely difficult to detect with prehistoric or unobserved eruptions.
[[Marketing co-operation]]
==Classification==
{| class="wikitable"
!VEI
!Classification
!Description
!Plume
!Ejecta volume
!Frequency
!Example
!Occurrences †
|-
! 0
|[[Hawaiian Eruption|Hawaiian]] || non-explosive || < 100 m || > 1000 m³ || daily || [[Kilauea]] || -
|-
! 1
| Hawaiian/[[Strombolian Eruption|Strombolian]] || gentle || 100-1000 m || > 10,000 m³ || daily || [[Stromboli]] || -
|-
! 2
| Strombolian/Vulcanian || explosive || 1-5 km || > 1,000,000 m³ || weekly || [[Galeras]] ([[1993]])|| 3477†
|-
! 3
| [[Vulcanian Eruption|Vulcanian]]/Pelean || severe || 3-15 km || > 10,000,000 m³ || yearly || [[Nevado del Ruiz]] ([[1985]])|| 868
|-
! 4
| Pelean/Plinian|| cataclysmic || 10-25 km || > 0.1 km³ || ≥ 10 yrs || [[Galunggung]] ([[1982]])|| 278
|-
! 5
| [[Plinian Eruption|Plinian]] || paroxysmal || > 25 km || > 1 km³ || ≥ 50 yrs || [[Mount St. Helens|St. Helens]] ([[1980]])|| 84
|-
! 6
| Plinian/Ultra-Plinian || colossal|| > 25 km || > 10 km³ || ≥ 100 yrs || [[Mt Pinatubo]] ([[1883]])|| 39
|-
! 7
| Plinian/Ultra-Plinian || super-colossal || > 25 km || > 100 km³ || ≥ 1000 yrs || [[Mount Tambora|Tambora]] ([[1815]])|| 4
|-
! 8
| Plinian/Ultra-Plinian || mega-colossal || > 25 km || > 1,000 km³ || ≥ 10,000 yrs || [[Lake Toba|Toba]] (73,000 [[Before present|BP]])|| -
|-
! 9
| Plinian/Ultra-Plinian || super-mega-colossal || > 25 km || > 10,000 km<sup>3</sup> || ≥ 100,000 years || ? || -
|-
! 10
| Plinian/Ultra-Plinian || hyper-mega-colossal || > 25 km || > 100,000 km<sup>3</sup> || ≥ 1,000,000 years || [[Deccan Traps]] (64,000,000 [[Before present|BP]]) || -
|-
! 11
| Plinian/Ultra-Plinian || ultra-mega-colossal || > 25 km || > 1,000,000 km<sup>3</sup> || ≥ 10,000,000 years || [[Siberian Traps]] (251 million years [[Before present|BP]])|| -
|}
''† Count of eruptions in the last 10,000 years based on 1994 figures maintained by the Global Volcanism Program of the [[Smithsonian Institution]]''
==List of eruptions==
{{listdev}}
[[Category:Marketing techniques]]
{| class="wikitable"
!VEI
!Name
!Year
|-
!rowspan=2|0
| [[Mauna Loa]] || [[1984]]
|-
| [[Piton de la Fournaise]] || [[2004]]
|-
!rowspan=2|1
| [[Kilauea]] || [[1983]] - present
|-
| [[Nyiragongo]] || [[2002]]
|-
!rowspan=5|2
| [[Mount Hood]] || [[1865]]-[[1866]]
|-
| [[Kilauea]] || [[1924]]
|-
| [[Tristan da Cunha]] || [[1961]]
|-
| [[Whakaari/White Island]] || [[2001]]
|-
| [[Mount Usu]] || [[2000]]-[[2001]]
|-
!rowspan=5|3
| [[Mount Vesuvius]] || [[1913]]-[[1944]]
|-
| [[Surtsey]] || [[1963]]-[[1967]]
|-
| [[Eldfell]] || [[1973]]
|-
| [[Nevado del Ruiz]] || [[1985]]
|-
| [[Mount Etna]] || [[2002]]-[[2003]]
|-
!rowspan=5|4
| [[Mount Pelée]] || 1902
|-
| [[Parícutin]] || [[1943]]-[[1952]]
|-
| [[Hekla]] || [[1947]]
|-
| [[Galunggung]] || [[1982]]
|-
| [[Mount Spurr]] || [[1992]]
|-
!rowspan=5|5
| [[Mount Vesuvius]] ([[Pompeii]] eruption) || [[79]]
|-
| [[Mount Agung]] || [[1963]]
|-
| [[Mount St. Helens]] ([[1980 Mount St. Helens eruption|1980 eruption]]) || [[1980]]
|-
| [[El Chichón]] || [[1982]]
|-
| [[Mount Hudson]] || [[1991]]
|-
!rowspan=10|6
| [[Mount Etna]] <!-- VEI 6+ --> || 8000 [[before present|BP]]?
|-
| [[Mount Vesuvius]] ([[Avellino eruption]]) <!-- VEI 6+ --> || [[1660s BC|1660 BC]] ± 43 years
|-
| [[Santorini]] ([[Minoan eruption]]) <!-- 30-60 cubic km = VEI 6.5 --> || [[1620s BC]] or [[1520s BC]]
|-
| [[Ilopango (volcano)|Ilopango]] || [[450]] ± 30 years
|-
| [[Baekdu Mountain]] ([[Chonji|Tianchi]] eruption) <!-- 90 cubic km == VEI 6.9 --> || [[1000]]
|-
| [[Kuwae]] || [[1452]] or 1453
|-
| [[Laki]] <!-- 20 cubic km == VEI 6.3 --> || [[1783]]
|-
| [[Krakatoa]] <!-- 30 cubic km == VEI 6.5 --> || [[1883]]
|-
| [[Novarupta]] ([[1912 Novarupta eruption|1912 eruption]]) <!-- 30 cubic km == VEI 6.5 --> || [[1912]]
|-
| [[Mount Pinatubo]] <!-- 10 cubic km = VEI 6.0 --> || [[1991]]
|-
!rowspan=7|7
| [[Yellowstone Caldera|Yellowstone]] ([[Mesa Falls Tuff|Mesa Falls eruption]]) <!-- 700 cubic km = VEI 7+ --> || 1,300,000 [[Before Present|BP]]
|-
| [[Long Valley Caldera]] <!-- 550 cubic km = VEI 7.75 --> || 760,000 [[Before Present|BP]]
|-
| [[Kurile Lake|Kurile]] <!-- VEI 7 --> || [[6440 BC]] ± 25 years
|-
| [[Crater Lake National Park|Crater Lake Oregon]] ([[Mount Mazama|Mount Mazama eruption]]) <!-- 104 cubic km = VEI 7.0 --> || [[4860 BC]]
|-
| [[Kikai Caldera|Kikai]] ([[Akahoya eruption]]) <!-- 150 cubic km = VEI 7.0 --> || [[4350 BC]]
|-
| [[Lake Taupo|Taupo]] <!-- 100-120 cubic km = VEI 7.0 --> || [[181]]
|-
| [[Mount Tambora]] <!-- 100-150 cubic km = VEI 7.0 --> || [[1815]]
|-
!rowspan=5|8
| [[La Garita Caldera]] <!-- 5,000 cubic km = VEI 8.6 --> || 27 million years [[Before Present|BP]]
|-
| [[Yellowstone Caldera|Yellowstone]] ([[Huckleberry Ridge Tuff|Huckleberry Ridge eruption]]) <!-- 2400 cubic km = VEI 8.4 --> || 2,200,000 [[Before Present|BP]]
|-
| [[Yellowstone Caldera|Yellowstone]] ([[Lava Creek Tuff|Lava Creek eruption]]) <!-- 1000 cubic km = VEI 8.0 --> || 640,000 [[Before Present|BP]]
|-
| [[Lake Toba|Toba]] <!-- 2800 cubic km = VEI 8.45 --> || 73,000 [[Before Present|BP]]
|-
| [[Lake Taupo|Taupo]] ([[Oruanui eruption]]) <!-- 1170 cubic km = VEI 8.1 --> || 26,500 [[Before Present|BP]]
|-
!rowspan=2|10
| [[Columbia River Basalt Group]] || 16.5 million years [[before present|BP]]
|-
| [[Deccan Traps]] || 64 million years [[before present|BP]]
|-
!rowspan=1|11
| [[Siberian Traps]] || 251 million years [[before present|BP]]
|}
Note that there have not been any [[Holocene]] (within the last 10,000 years) eruptions with a VEI of 8. Lake Taupo's [[Oruanui eruption]] is probably the most recent, occurring 26,500 years ago. There is a new theory that the [[Minoan eruption]] of [[Santorini]] may have been twice as large as originally thought, placing it behind [[Lake Taupo|Taupo]]'s 181 eruption and [[Mount Tambora]] as the third largest eruption in recorded history.<ref>McCoy, F. W. and Dunn, S., 2002, Modelling the Climatic Effects fo the LBA Eruption of Thera: New Calculations of Tephra Volumes May Suggest a Significantly Larger Eruption than Previously Reported [abst.]; Proceedings of the Chapman Conference on Volcanism and the Earth’s Atmosphere, Am. Geophysical Union, Santorini, Greece: 21-22.</ref>
==See also==
*[[Supervolcano]]
*[[List of volcanoes]]
*[[List of deadliest natural disasters]]
==Footnotes==
<references/>
==References==
* Christopher G. Newhall and Steve Self (''[[Journal of Geophysical Research]]'', v. 87, p. 1231–1238, [[1982]])
*{{cite journal
| author = Ben G. Mason
| coauthors = David M. Pyle, and Clive Oppenheimer
| year = 2004
| title = The size and frequency of the largest explosive eruptions on Earth
| journal = Bulletin of Volcanology
| volume = 66
| issue = 8
| pages = 735-748
| doi = 10.1007/s00445-004-0355-9
| format = PDF
| accessdate = 2006-07-14
}}
==External links==
* [http://volcanoes.usgs.gov/Products/Pglossary/vei.html VEI glossary entry] from a [[United States Geological Survey|USGS]] website
* [http://talk.workunlimited.co.uk/life/feature/story/0,13026,1294868,00.html How to measure the size of a volcanic eruption], from ''[[The Guardian]]''
* [http://springerlink.metapress.com/openurl.asp?genre=article&id=doi:10.1007/s00445-004-0355-9 The size and frequency of the largest explosive eruptions on Earth], a 2004 article from the ''[[Bulletin of Volcanology]]''
* [http://www.volcano.si.edu/world/largeeruptions.cfm List of Large Holocene Eruptions (VEI > 4) from the Smithsonian Global Volcanism Program]
[[Category:Volcanology]]
[[Category:Scales]]
[[de:Vulkanexplosivitätsindex]]
[[fa:نمایه شدت فوران آتشفشان]]
[[fr:Indice d'explosivité volcanique]]
[[it:VEI]]
[[nl:Vulkanische Explosiviteits Index]]
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