The
Volcanic Explosivity Index 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.