What is the Volcanic Explosivity Index?

The VEI is a logarithmic scale from 0 to 8 that measures the relative explosiveness of volcanic eruptions. Each step up the scale represents roughly a tenfold increase in erupted material.

What is the most destructive VEI ever recorded?

The largest eruptions in recorded human history reached VEI 7, including the 1815 Tambora eruption. VEI 8 "supervolcano" events (such as Yellowstone and Toba) are known from the geologic record but have not occurred in historical times.

How is VEI different from the Richter scale?

The Richter (and moment-magnitude) scale measures seismic energy released by earthquakes. VEI measures the volume of tephra (ash and rock fragments) ejected by a volcanic eruption — they describe completely different physical phenomena.

Is a VEI 5 eruption ten times bigger than VEI 4?

Roughly, yes. VEI is a logarithmic scale, so each step represents about a tenfold increase in erupted volume. A VEI 5 eruption ejects around ten times more material than a VEI 4.

How often do VEI 8 eruptions happen?

VEI 8 eruptions occur on average once every 50,000–100,000 years. The last known VEI 8 event was the Toba supervolcano eruption approximately 74,000 years ago.

Volcanic Explosivity Index

Look up each VEI level (0–8), see what it means, and find real historical eruptions at that level.

Select a VEI Level

Erupted Volume Comparison (log scale)

Historical Eruptions at This Level

Summary

The Volcanic Explosivity Index (VEI) is a logarithmic scale from 0 to 8 used by geologists to compare the relative explosiveness of volcanic eruptions. Each step represents roughly a tenfold increase in the volume of ejected material (tephra). This reference tool lets you explore every level of the scale, see typical column heights and erupted volumes, and browse well-known historical eruptions assigned to each level.

How it works

Select a VEI level (0–8) from the scale bar or the level cards below.
The detail panel shows column height, erupted volume, and frequency for that level.
Scroll through real historical eruptions recorded at that level.
Use the comparison view to see all levels side-by-side on a logarithmic bar chart.

Use cases

Understand how geologists classify volcanic eruptions.
Research specific eruptions for geology coursework or presentations.
Compare the relative power of famous eruptions like Krakatoa and Mount St. Helens.
Learn why the VEI scale is logarithmic and what that means in practice.
Quickly look up the erupted volume or plume height for a given VEI level.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu