I’m trying to wrap my head around something that appears far more complex than I first thought. I don’t understand the explosive elements and chemistry that drives ash production and the heat to create the eruption column. I’m aware of how molten metal behaves in a foundry crucible with flux and degassing required. So I understand how magmas can have a tremendous amount of dissolved elements that can release like CO2 from a shaken soda bottle being opened. I can picture this kind of pyroclastic flow easily; the “shaken soda bottle” type.
I don’t have a very good grasp of how the ash column can reach enormous heights and then collapse, or how composition impacts this kind of collapse. I just can’t picture in my mind how this type of collapse results in a flow, like some kind of avalanche or pronounced river of material as opposed to more of a micro-regional rain like ash fall event that is very intense and superheated. What is the trigger and how does it overcome any hotter material lower in the column?
Here are some resources to clear up the difference between eruptions and flows and provide more context to answer your question.
Background on explosive eruptions: https://youtu.be/tQzaQd72DJI?si=wmhLU3TjlRuiKvJW
Part 2 (more interesting from my pov): https://youtu.be/umNWZOTHFXo?si=ZfmHJCEnQ_eil87I
Timestamp ~30:10 on the second video (Lesson 10) talks about the origin of pyroclastic flows.
Thanks. I watched both of them. That cleared up the missing pieces.