The Volcanic Explosivity Index (VEI): Comparing Eruptions

Volcanic Explosivity Index VEI 0 to 8 with examples Kilauea, Etna, Mt St Helens, Pinatubo, Tambora and Yellowstone, each level about 10 times more material

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Volcanoes are big, so eruptions are big. But how big? And how would you compare one eruption with another? Well, like the Richter Scale for earthquakes, there’s a scale for eruptions. It’s called the Volcanic Explosivity Index.

What Is the Volcanic Explosivity Index?

The Volcanic Explosivity Index (VEI) ranges from 0 to 8. It covers everything from a shoot of ash with a trickle of lava (Effusive), for example, Hawaii’s Kīlauea volcano, to the mega-colossal explosions in the distant past from the Yellowstone caldera, the largest supervolcano in North America.

Volcanoes erupt in different ways, and the index uses several measures, such as the volume of ash (tephra) ejected and the height and scale of the plume and ash clouds. And some eruptions are sudden, while others go on for years.

Because of this difficulty in classification, one division I like is red volcanoes and grey volcanoes. A red volcano is an effusive eruption with lava and often a lava lake, like Hawaii’s Kīlauea. A classic grey volcano eruption is Mt St Helens that created an ash cloud rising to around 15 miles above the summit.

Like the Richter scale, the Volcanic Explosivity Index is a logarithmic scale. This means that, after the first levels, each level ejects roughly ten times more material than the previous(!)—hence the sketch not being to scale.

Volcanic Explosivity Index and Example Eruptions

Here’s the scale with associated adjectives, approximate sizes of the eruption column, and some example eruptions you may have heard of:

0 · Effusive or Non-explosive
100m, Kīlauea (Hawaii, current)

1 · Gentle/Mild
100m–1 km

2 · Explosive
1–5 km, Mt Etna (Italy, 2006 and many others)

3 · Severe
3–15 km

4 · Cataclysmic
10–25 km, Eyjafjallajökull (Iceland, 2010)

5 · Paroxysmal
20–35 km, Mt St Helens (USA, 1980)

6 · Colossal
>30 km, Pinatubo (Philippines, 1991), Krakatoa (1883)

7 · Super-colossal
>40 km, Tambora (Indonesia, 1815)

8 · Mega-colossal
> 50km (uncertain, though massive), Yellowstone (USA, several times...)

On a personal note, some of my favourite places in the UK are the museums in South Kensington, London. The Earth galleries in the Natural History Museum are always fascinating and inspiring. I learned about the volcanic explosivity index there and had been meaning to sketch it for at least ten years.

The descriptive adjectives for each level vary slightly across the sources I’ve seen. In particular, levels 4 and 5 are sometimes 4 Catastrophic and 5 Cataclysmic. But I liked the labels the Natural History Museum uses, including Paroxysmal.

Learn more about the VEI

The USGS (United States Geological Survey) have a helpful article on the VEI from geophysicist Michael Poland.

And you can read the original 1982 paper that proposes the scale from volcanologists Chris Newhall and Steve Self: The Volcanic Explosivity Index (VEI): An Estimate of Explosive Magnitude for Historical Volcanism (archived pdf), Journal of Geophysical Research

Related Ideas to the Volcanic Explosivity Index

Some more scales:

More volcanoes:

Published 15 Feb 2026

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Transverse dunes typically have a shallower up slope in the direction the wind arrives from and a steeper slip slope on the sheltered side. I learned that the shallower upface is called the stoss side, and the steeper slipface is called the lee face. Linear Dunes When wind blows from two directions, dunes can be pulled into long, linear ridges, forming longitudinal dunes or linear dunes. The ridges align with the average direction of the wind. Some ridges can run for a hundred miles. In contrast to transverse dunes, wind from both directions creates slip faces on both sides, often forming sharp edges along the dune ridges. This leads to the more poetic name of seif dunes, meaning sword in Arabic. Barchan Dunes When the prevailing wind is from one direction and sand is less plentiful, crescent-shaped barchan dunes form. They have characteristic horns extending in the direction the wind blows. 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It’s fascinating to observe both at a tiny scale on the beach and flying over a vast desert. Transverse dunes typically have a shallower up slope in the direction the wind arrives from and a steeper slip slope on the sheltered side. I learned that the shallower upface is called the stoss side, and the steeper slipface is called the lee face. Linear Dunes When wind blows from two directions, dunes can be pulled into long, linear ridges, forming longitudinal dunes or linear dunes. The ridges align with the average direction of the wind. Some ridges can run for a hundred miles. In contrast to transverse dunes, wind from both directions creates slip faces on both sides, often forming sharp edges along the dune ridges. This leads to the more poetic name of seif dunes, meaning sword in Arabic. Barchan Dunes When the prevailing wind is from one direction and sand is less plentiful, crescent-shaped barchan dunes form. They have characteristic horns extending in the direction the wind blows. Sands are always shifting, and barchan dunes can move relatively quickly along the desert floor compared to other large dunes. Star Dunes When winds blow from many directions, sand can get blown into dunes that grow vertically in a star or pyramid shape. Remarkably, they can reach up to 500m tall. In some areas, star dunes form along longitudinal ridges. Other Dune Types The interactions of sand and wind are endlessly complex, and other types of dunes exist. These include: Dome dunes, without prominent ridges, as you might imagine Parabolic dunes, which look like barchan but face the opposite way. Look out for these near the coast. Reversing dunes, which have a sort of mini-dune facing the opposite way at the top of the ridge. Draas: mega-dunes sometimes made up of other dune forms. Related Ideas to Common Dune Types Also see: The 3 Tallest Mountains Tectonic Plate Interaction Boundaries Settlement Patterns Shapes of Valleys One hump or two hump camel? Topography - Bathymetry Rain Shadow Types of Surf Break Strand line Point Nemo — the remotest place in the oceans

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