Editing Eruption column (section)

==Formation==
[[File:Pinatubo91eruption plume.jpg|thumb|upright=1.35|Eruption column over [[Mount Pinatubo]] in the [[Philippines]], 1991]]
Eruption columns form in explosive volcanic activity, when the high concentration of [[Volatile (astrogeology)#Igneous petrology|volatile materials]] in the rising [[magma]] causes it to be disrupted into fine [[volcanic ash]] and coarser [[tephra]]. The ash and tephra are ejected at speeds of several hundred metres per second, and can rise rapidly to heights of several kilometres, lifted by enormous [[convection]] currents.

Eruption columns may be transient, if formed by a discrete explosion, or sustained, if produced by a continuous eruption or closely spaced discrete explosions.