The Volcanic Explosivity Index

The VEI Scale, Level by Level

The single most important thing to understand about VEI is that it is logarithmic. The jump from a VEI 4 to a VEI 5 isn't "a bit bigger" — it's roughly ten times more erupted material. That's why the numbers stay small even for eruptions of wildly different scale. Here's the full scale, with a real example and the number of eruptions our database has recorded at each level.

What the VEI Distribution Actually Looks Like

Every explainer shows you the scale. Almost none show you the data — how eruptions really distribute across it. So we counted. Of the 11,079 eruptions in our database, 8,394 carry a recorded VEI. Here's how they break down:

Two things jump out. First, VEI 2 is by far the most common— 4,020 eruptions, the "explosive but routine" middle of the scale that keeps volcanoes like Etna and Sakurajima in the news without threatening anyone far away. Second, the drop-off past VEI 4 is brutal, and it's the logarithmic scale showing up in real data:

• 754 eruptions reached VEI 4 or higher (cataclysmic — big enough to disrupt aviation across a region).
• 240 reached VEI 5 or higher — the Mount St. Helens 1980 class.
• 59 reached VEI 6 or higher — the Pinatubo / Krakatau class capable of measurable global cooling.
• Only 7 reached VEI 7, and none reached VEI 8 within the dated record.

In other words, for every single VEI 7 super-colossal eruption in the catalogue, there are more than 570 VEI 2s. The really destructive eruptions are rare precisely because the scale climbs so fast.

One volcano owns a startling share of those big eruptions. Count the VEI 4+ eruptions per volcano and Shiveluch in Kamchatka tops the entire database with 43 — more than double the next volcano — and it has been erupting almost daily through 2026.

Famous Eruptions at Each VEI Level

Putting names to numbers makes the scale click. Each of these is graded in our database — the linked ones have a full volcano profile with eruption history.

• VEI 1–2 — Stromboli and Galeras: the everyday explosive eruptions that define a "Strombolian" or "Vulcanian" style (see our guide to eruption types).
• VEI 3 — Nevado del Ruiz 1985: modest in volume, but its lahars killed ~23,000 people — proof that VEI doesn't equal death toll.
• VEI 4 — Eyjafjallajökull 2010: small on the scale, but its ash grounded European aviation for days.
• VEI 5 — Mount St. Helens 1980: the benchmark most Americans picture when they think "eruption."
• VEI 6 — Pinatubo 1991 and Krakatau 1883: big enough to cool the whole planet for a year or two.
• VEI 7 — Tambora 1815: the largest eruption in recorded history, which caused the Year Without a Summer.
• VEI 8 — Toba (~74,000 years ago) and Yellowstone: the supervolcano class, none of which has erupted in human history.

VEI 8: What a Super-Eruption Actually Means

VEI 8 sits alone at the top of the scale — an eruption that ejects more than 1,000 km³ of material, a hundred times bigger than Pinatubo. It's the level people mean when they say "supervolcano." The consequences aren't just local: a VEI 8 injects so much sulfur into the stratosphere that it triggers a volcanic winter — years of global cooling, dimmed skies, and failed harvests.

Here's the reassuring part, and it's in the data above: our database records zero VEI 8 eruptions in the dated record. The most recent, the Toba super-eruption, was around 74,000 years ago; the last full-scale Yellowstone eruption was ~640,000 years ago. The USGS puts the annual probability of a Yellowstone super-eruption at roughly 1 in 730,000. When a headline warns a supervolcano is "overdue," remember that these are the rarest eruptions on Earth — and that VEI 8 has never been witnessed by written history.

VEI vs the Richter Scale — and What VEI Misses

VEI is often called "the Richter scale for volcanoes," and the analogy is fair: both are logarithmic, both compress enormous ranges into small numbers. But they measure completely different things — Richter (and its successor, moment magnitude) measures earthquake energy; VEI measures erupted volume. A volcano can rate a high VEI and produce almost no felt earthquakes, and vice versa.

VEI also has real blind spots worth knowing:

• It ignores effusive eruptions. A massive but gentle lava flow — like Iceland's 1783 Laki fissure, which killed a fifth of the country — rates only VEI 4 because it wasn't explosive.
• It doesn't measure lethality. Nevado del Ruiz (VEI 3) killed far more people than St. Helens (VEI 5). Death toll depends on lahars, location and warning, not raw explosivity.
• It struggles underwater. Deep submarine eruptions are hard to grade because their ejecta is quenched and hidden.

For those reasons, researchers increasingly pair VEI with the magma (or dense-rock) volume and with sulfur output — the metric that actually drives climate impact. VEI is the best single number we have, but it's a starting point, not the whole story.