Ash dispersion models

VAFTAD: Volcanic Ash Forecast Transport And Dispersion by NOAA Air Resources Laboratory (ARL).

CANERM: Canadian Emergency Response Model by the Canadian Meteorological Centre (CMC).

PUFF: A Langrangian trajectory volcanic ash tracking model.  Paper JGR article describing PUFF.

Useful volcanic hazards web sites

USGS Hazards Program

GVP Smithsonian Institution