Pyroclastic fall (original) (raw)

A pyroclastic fall is a uniform deposit of material which has been ejected from a volcanic eruption or plume such as an ash fall or tuff. Pyroclastic air fall deposits are a result of: 1. * Ballistic transport of ejecta such as volcanic blocks, volcanic bombs and lapilli from volcanic explosions 2. * Deposition of material from convective clouds associated with pyroclastic flows such as coignimbrite falls 3. * Ejecta carried in gas streaming from a vent. The material under the action of gravity will settle out from an eruption plume or eruption column 4. * Ejecta settling from an eruptive plume or eruption column that is displaced laterally by wind currents and is dispersed over great distances