Volcanic explosivity index
The index was devised by Chris Newhall of the U.S. Geological Survey and Steve Self at the University of Hawaii in 1982 to provide a relative measure of the explosiveness of eruptions.
Volume of products, eruption cloud height, and qualitative observations (from Gentle to Cataclysmic) are used to determine the explosivity value. The scale is open-ended and ranges from 0, for non-explosive eruptions (less than 104 cubic metres of tephra ejected), to 8, for explosive eruptions larger than any in history (1012 cubic metres of tephra and a cloud column height of over 25 km). Values higher than 8 can be determined if needed.
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | |
|---|---|---|---|---|---|---|---|---|---|
| Total Historic Eruptions | 487 | 623 | 3176 | 733 | 119 | 19 | 5 | 2 | 0 |