Volcanic explosivity index
The volcanic explosivity index (VEI) is a relative measure of the explosiveness of volcanic eruptions. It was devised by Christopher G. Newhall of the United States Geological Survey and Stephen Self in 1982.
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 eruptions in history given a magnitude of 8. A value of 0 is given for non-explosive eruptions, defined as less than 10,000 m3 (350,000 cu ft) of
Classification
With indices running from 0 to 8, the VEI associated with an eruption is dependent on how much volcanic material is thrown out, to what height, and how long the eruption lasts. The scale is logarithmic from VEI-2 and up; an increase of 1 index indicates an eruption that is 10 times as powerful. As such, 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 one hundred, from 10,000 to 1,000,000 m3 (350,000 to 35,310,000 cu ft), while the factor is ten between all higher indices. In the following table, the frequency of each VEI indicates the approximate frequency of new eruptions of that VEI or higher.
VEI | Ejecta volume (bulk) |
Classification | Description | Plume | Periodicity | Tropospheric injection |
Stratospheric injection[2] |
---|---|---|---|---|---|---|---|
Examples | |||||||
0 | < 104 m3 | Hawaiian | Effusive | < 100 m | constant | negligible | none |
Kīlauea (current), Mawson Peak (current), Dallol (2011), Holuhraun (2014-2015), Fagradalsfjall (2021-2023), Mauna Loa (1975, 1984, 2022) | |||||||
1 | > 104 m3 | Hawaiian / Strombolian | Gentle | 100 m – 1 km | daily | minor | none |
Yakedake (1995), Raoul Island (2006), Havre Seamount (2012), Dieng Volcanic Complex (1964, 1979, 2017), Nyiragongo (1977, 2002, 2021) | |||||||
2 | > 106 m3 | Strombolian / Vulcanian | Explosive | 1–5 km | 2 weeks | moderate | none |
) | |||||||
3 | > 107 m3 | Strombolian / Vulcanian / Peléan / Sub-Plinian | Severe | 3–15 km | 3 months | substantial | possible |
Surtsey (1963-1967), Nevado del Ruiz (1985), Redoubt (1989-1990), Soufrière Hills (1997), Ontake (2014), Fuego (2018), Cumbre Vieja (2021) | |||||||
4 | > 0.1 km3 | Peléan / Plinian / Sub-Plinian | Catastrophic | > 10 km | 18 months | substantial | definite |
Laki (1783), Bandai (1888), Pelée (1902), Lamington (1951), Eyjafjallajökull (2010), Merapi (2010), Taal (2020), Semeru (2021) | |||||||
5 | > 1 km3 | Peléan / Plinian | Cataclysmic | > 10 km | 12 years | substantial | significant |
Vesuvius (79), Fuji (1707), Tarawera (1886), St. Helens (1980), El Chichón (1982), Puyehue (2011), Hunga Tonga–Hunga Haʻapai (2022) | |||||||
6 | > 10 km3 | Plinian / Ultra-Plinian |
Colossal | > 20 km | 50–100 years | substantial | substantial |
Santorini (1620 BC), Lake Ilopango (450), Huaynaputina (1600), Krakatoa (1883), Santa Maria (1902), Novarupta (1912), Pinatubo (1991) | |||||||
7 | > 100 km3 | Ultra-Plinian | Super-colossal | > 20 km | 500–1,000 years | substantial | substantial |
Long Valley (760 kyr), Campi Flegrei (37 kyr), Aira (22 kyr), Mazama (5700 BC), Kikai (4300 BC), Samalas (1257), Tambora (1815) | |||||||
8 | > 1,000 km3 | Ultra-Plinian | Mega-colossal | > 20 km | > 50,000 years[3][4] | vast | vast |
Flat Landing Brook (Ordovician), Wah Wah Springs (30 Mya), La Garita (26.3 Mya), Yellowstone (2.1 Mya, 640 kyr), Toba (74 kyr), Taupō (26.5 kyr) |
There have been at least 10 eruptions of VEI-7 in the last 11,700 years. There are also 58 Plinian eruptions, and 13 caldera-forming eruptions, of large, but unknown magnitudes. By 2010, the Global Volcanism Program of the Smithsonian Institution had cataloged the assignment of a VEI for 7,742 volcanic eruptions that occurred during the Holocene (the last 11,700 years) which account for about 75% of the total known eruptions during the Holocene. Of these 7,742 eruptions, about 49% have a VEI of 2 or lower, and 90% have a VEI of 3 or lower.[7]
Limitations
Under the VEI, ash, lava, lava bombs, and ignimbrite are all treated alike. Density and vesicularity (gas bubbling) of the volcanic products in question is not taken into account. In contrast, the DRE (dense-rock equivalent) is sometimes calculated to give the actual amount of magma erupted. Another weakness of the VEI is that it does not take into account the power output of an eruption, which makes the VEI extremely difficult to determine with prehistoric or unobserved eruptions.
Although VEI is quite suitable for classifying the explosive magnitude of eruptions, the index is not as significant as sulfur dioxide emissions in quantifying their atmospheric and climatic impact.[8]
Lists of notable eruptions
- Timeline of volcanism on Earth (mostly VEI-6, within 2 kya)
- List of volcanic eruptions 1500–1999
- List of volcanic eruptions in the 21st century
- List of volcanic eruptions by death toll
- List of large Holocene volcanic eruptions (VEI-5–7)
- List of large volcanic eruptions (VEI-5–8, within 450+ Mya)
- List of largest volcanic eruptions (VEI-7–8, mostly within 500 Mya)
See also
- Supervolcano – Volcano that has erupted 1000 cubic km of lava in a single eruption
- Decade Volcanoes – Set of sixteen volcanoes noted for their eruptive history and proximity to densely populated areas
- Dispersal index – Indicator of spread of volcanic ejecta
- Lists of volcanoes
- List of natural disasters by death toll
References
- ^
Newhall, Christopher G.; Self, Stephen (1982). "The Volcanic Explosivity Index (VEI): An Estimate of Explosive Magnitude for Historical Volcanism" (PDF). doi:10.1029/JC087iC02p01231. Archived from the original(PDF) on December 13, 2013.
- ^ "Volcanic Explosivity Index (VEI)". Global Volcanism Program. Smithsonian National Museum of Natural History. Archived from the original on November 10, 2011. Retrieved August 21, 2014.
- ^ ISBN 978-1-4443-3260-5.
- ^ Rothery, David A. (2010), Volcanoes, Earthquakes and Tsunamis, Teach Yourself
- ^ a b
Mason, Ben G.; Pyle, David M.; Oppenheimer, Clive (2004). "The size and frequency of the largest explosive eruptions on Earth". S2CID 129680497.
- .
- ^
Siebert, L.; Simkin, T.; Kimberly, P. (2010). Volcanoes of the World (3rd ed.). ISBN 978-0-520-26877-7.
- S2CID 53005926.
External links
- VEI glossary entry from a USGS website
- How to measure the size of a volcanic eruption, from The Guardian
- The size and frequency of the largest explosive eruptions on Earth, a 2004 article from the Bulletin of Volcanology
- List of Large Holocene Eruptions (VEI > 4) from the Smithsonian Global Volcanism Program Archived 2012-01-17 at the Wayback Machine