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Volcanic Explosivity Index

An index published in 1982 by Christopher Newhall and Stephen Self, for rating the explosivity of volcanic eruptions.¹ Acronym, VEI.

1. Christopher G. Newhall and Stephen Self.
The volcanic explosivity index (VEI): An estimate of explosive magnitude for historical volcanism.
Journal of Geophysical Research, volume 87 number C2, pages 1231-1238 (20 February 1982).

Criteria¹	Volcanic Explosivity Index
Criteria¹	0	1	2	3	4	5	6	7	8
Description	non-explosive	small	moderate	moderate to large	large	very large
Volume of ejecta (cubic meters)	<10⁴	10⁴– 10⁶	10⁶– 10⁷	10⁷– 10⁸	10⁸– 10⁹	10⁹– 10¹⁰	10¹⁰– 10¹¹	10¹¹– 10¹²	>10¹²
Tsuya class²	I	II-III	IV	V	VI	VII	VIII	IX
Column height (kilometers)³	<0.1	0.1-1	1-5	3-15	10-25	>25
Qualitative description	gentle, effusive		explosive		cataclysmic, paroxysmal, colossal
Qualitative description				severe, violent, terrific
Classifications		Strombolian			Plinian
Classifications	Hawaiian		Vulcanian			Ultraplinian
Duration of continuous blast (hours)	<1				>12
			1-6
				6-12
CAVW maximum explosivity⁴	lava flows	explosion or nuée ardente
		phreatic
	dome or mudflow
Tropospheric injection	negligible	minor	moderate	substantial
Stratospheric injection	none	none	none	possible	definite	significant

After Newhall and Self.

notes on criteria

1. Criteria are listed in decreasing order of reliability.

2. Tsuya classification (based on volume of ejecta), assuming pyroclastic flows. The scale is defined in:

H. Tsuya.
Geological and petrological studies of volcano Fuji, 5.
Tokyo Daigaku Jishin Kenkyusho Iho, volume 33, pages 3-382 (1955).

3. For VEI's 0 – 2, measured from the crater rim; for VEI's 3 – 8, measured from sea level.

4. Most explosive activity indicated for the eruption in the Catalog of Active Volcanoes of the World.

Some examples of VEI ratings

Volcano	Date of Eruption	VEI
Kilauea, Hawaii, U.S.	almost continuous	0
Nyiragongo, Dem. Rep. of Congo	began 17 January 2002	1
Soufriere Hills, Montserrat	began 18 July 1995	3
Eyjafyallajökull, Iceland	2010	4
Mt. St. Helens U.S.	18 May 1980	5
Mt. St Helens, U.S.	1540 ± 70	5
Krakatau, Indonesia	26 Aug 1883	6
Tambora, Indonesia	5 April 1815	7
Samalas, Indonesia	1257	7
Yellowstone, U.S.	1.3 million years ago, 2.8 × 10¹¹	7
Yellowstone, U.S.	630,000 years ago, 1 × 10¹²	8
Yellowstone, U.S.	2 million years ago, 2.5 × 10¹²	8

Note: Because of the open-ended nature of the scale, for the Yellowstone eruptions we have provided the volume of ejecta in cubic meters as estimated by the U.S. Geological Survey.

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