- Volume of material erupted (also called ejecta or tephra)
- Height of the eruptive column
- Qualitative descriptions (i.e., "effusive", "explosive", "paroxysmal")
- Classification (Hawaiian, Strombolian, Vulcanian, Plinian, Ultraplinian)
- Duration in hours
- The most explosive type of activity observed
- Tropospheric (up to ~10 km) and stratospheric (~10-50 km) injection of material (i.e., did the eruption column reach these atmospheric levels?
Ready, Steady, Blow! Volcano Betting Erupts! (Paddy Power website)
Newhall, C. and Self, S., 1982, The Volcanic Explosivity Index (VEI): An Estimate of Explosive Magnitude for Historical Volcanism. Journal of Geophysical Research, v. 87, no. C2, p. 1231-1238.