For pre-historic eruptions, this scale is calculated based upon the dispersal of the volcanic products- i.e how far and wide they are scattered. Volcanic eruptions that have very tall columns will spread tephra far and wide.
created by Lorrie Lava, lava@pele.bigu.edu
Volcanic Studies, Big University
last modified: April 1, 1995
URL: http://www.bigu.edu/web/height.html