Volcanic Explosivity Index
The Volcanic Explosivity Index was devised by Chris Newhall of the
U.S. Geological Survey and Steve Self at the
University of Hawaii in 1982 to provide a relative measure of the explosiveness of
volcanic eruptions.
Volume of products, eruption cloud height, and qualitative observations are used to determine the explosivity value. The scale is open-ended and ranges from 0, for non-explosive eruptions to 8, for mega-colossal explosive eruptions that can eject 1012 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.
Encyclopedia
The
Volcanic Explosivity Index was devised by Chris Newhall of the
U.S. Geological Survey and Steve Self at the
University of Hawaii in 1982 to provide a relative measure of the explosiveness of
volcanic eruptions.
Volume of products, eruption cloud height, and qualitative observations are used to determine the explosivity value. The scale is open-ended and ranges from 0, for non-explosive eruptions to 8, for mega-colossal explosive eruptions that can eject 10
12 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.
Note that
ash,
volcanic bombs, and
ignimbrite are all treated alike - this is due to taking into account of the vesicularity of the volcanic products in question and the DRE 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.
Classification
| VEI | Classification | Description | Plume | Ejecta volume | Frequency | Example | Occurrences † |
|---|
| 0 | Hawaiian | non-explosive | < 100 m | > 1000 m³ | daily | Kilauea | - |
|---|
| 1 | Hawaiian/Strombolian | gentle | 100-1000 m | > 10,000 m³ | daily | Stromboli | - |
|---|
| 2 | Strombolian/Vulcanian | explosive | 1-5 km | > 1,000,000 m³ | weekly | Galeras | 3477† |
|---|
| 3 | Vulcanian/Pelean | severe | 3-15 km | > 10,000,000 m³ | yearly | Nevado del Ruiz | 868 |
|---|
| 4 | Pelean/Plinian | cataclysmic | 10-25 km | > 0.1 km³ | = 10 yrs | Galunggung | 278 |
|---|
| 5 | Plinian | paroxysmal | > 25 km | > 1 km³ | = 50 yrs | St. Helens | 84 |
|---|
| 6 | Plinian/Ultra-Plinian | colossal | > 25 km | > 10 km³ | = 100 yrs | Krakatoa | 39 |
|---|
| 7 | Plinian/Ultra-Plinian | super-colossal | > 25 km | > 100 km³ | = 1000 yrs | Tambora | 4 |
|---|
| 8 | Plinian/Ultra-Plinian | mega-colossal | > 25 km | > 1000 km³ | = 10,000 yrs | Toba | - |
|---|
† Count of eruptions in the last 10,000 years based on 1994 figures maintained by the Global Volcanism Program of the Smithsonian InstitutionList of eruptions
Note that there have not been any Holocene 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
Santorini Eruption may have been twice as large as originally thought, placing it behind
Taupo as the second largest eruption in human history.
See also
- Supervolcano
- List of volcanoes
- List of deadliest natural disasters
References
- Christopher G. Newhall and Steve Self
External links
...
website
- , from The Guardian is a British [i] newspaper [i] owned by the Guardian Media Group [i]. ...
- , a 2004 article from the Bulletin of Volcanology
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