The Volcanic Explosivity Index

The volcano explosivity index (VEI) is a scale used to measure the intensity of volcano eruptions.

  It is similar to the Richter and Mercalli scales, which measure the intensity of earthquakes. 

The VEI measures explosivity, volume of ash (tephra), and the height ash reaches into the atmosphere. 

Additionally, it gives a description of the eruption, a name for the eruption, and the total number of those eruptions in human history. 

See below for the VEI chart.

Note that in human history, there have been no VEI 8 eruptions. 

This does not mean that a VEI 8 eruption has not occurred sometime in the geologic past.

Below are pictures of eruptions of volcanoes from around the world, grouped according to their VEI number

Click on numbers for examples.

Criteria VEI
0 0 & 1 2 3 4 5 6 7 8
Description non-explosive small moderate moderate to large large very large huge humongous indescribable
Volume of ejecta
(cubic meters)
<104 104
106
106
107
107
108
108
109
109
1010
1010
1011
1011
1012
>1012
Column height
(kilometers)3
<0.1 0.1-1 1-5 3-15 10-25 >25
Qualitative
description
gentle, effusive explosive cataclysmic, paroxysmal, colossal
      severe, violent, terrific
Classifications   Strombolian   Plinian
Hawaiian Vulcanian Ultraplinian
Duration of
continuous blast (hours)
<1   >12
    1-6        
      6-12      
CAVW maximum explosivity 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 Chris Newhall and Steve Self.