Volcanic Explosivity Index

The Volcanic Explosivity Index (VEI) 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 volcanic 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.

VEI	0	1	2	3	4	5	6	7	8
Total Historic Eruptions	487	623	3176	733	119	19	5	2	0