Pyroclastic fall

Deposit of material ejected from a volcanic eruption

A pyroclastic fall deposit is a uniform deposit of material which has been ejected from a volcanic eruption or plume such as an ash fall or tuff. Pyroclastic fallout deposits are a result of:Ballistic transport of ejecta such as volcanic blocks, volcanic bombs and lapilli from volcanic explosions Deposition of material from convective clouds associated with pyroclastic flows such as coignimbrite falls 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 Ejecta settling from an eruptive plume or eruption column that is displaced laterally by wind currents and is dispersed over great distances

This keyword could refer to multiple things. Here are some suggestions: