Volcanic Explosivity Index

http://www.unc.edu/~rowlett/units/scales/VEI.html

http://volcanoes.usgs.gov/images/pglossary/vei.php

Column Height

http://www.geology.sdsu.edu/how_volcanoes_work/Thumblinks/erupttypes_page.html

http://english.turkcebilgi.com/Eruption+column

http://www.geology.sdsu.edu/how_volcanoes_work/Variability.html

A little bit of everything!!!

http://www.geo.mtu.edu/volcanoes/