Editing Eruption column (section)

===Column collapse===
[[File:MtStHelens Mushroom Cloud.jpg|thumb|The eruption column produced by the [[1980 eruption of Mount St. Helens]] as seen from the village of [[Toledo, Washington]], which is {{convert|35|mi|km|abbr=on|order=flip}} away. The cloud was roughly {{convert|40|mi|km|abbr=on|order=flip}} wide and {{convert|15|mi|km ft|abbr=on|order=flip}} high.]]
Eruption columns may become so laden with dense material that they are too heavy to be supported by convection currents. This can suddenly happen if, for example, the rate at which magma is erupted increases to a point where insufficient air is entrained to support it, or if the magma density suddenly increases as denser magma from lower regions in a [[Igneous differentiation|stratified]] [[magma chamber]] is tapped.

If it does happen, then material reaching the bottom of the convective thrust region can no longer be adequately supported by convection and will fall under [[gravity]], forming a [[pyroclastic flow]] or [[pyroclastic surge|surge]] which can travel down the slopes of a [[volcano]] at speeds of over {{convert|100-200|kph|mph|abbr=on}}. Column collapse is one of the most common and dangerous volcanic hazards in column-creating eruptions.