There is a wonderful diverse world of volcanic eruptions! One thing you might not have thought about is how glaciers often form at the top of large cone volcanoes and the way the lava erupting interacts with a large volume of ice can shape the eruption significantly. One of the biggest results are lahars, like muddy, liquidy avalanches but even faster and deadlier.

One of the thing that links all volcanic eruptions and is a good orientation point for comparing between different eruptions and volcanoes is that all magma pretty much comes up from the mantle to the near surface starting at the same chemical composition. If the magma feeds into large underground chambers (batholiths) and is allowed to cool slowly then certain minerals will begin to form and precipitate out like snow that layers up on the bottom of the chamber. What minerals these are depends on how long, how hot, how much pressure, but you can vaguely think of it as a process of distillation where magma progresses from the original “mafic” composition to a “felsic” one as the high temperature mafic minerals crystallize leaving behind the felsic magma mixture.

This is a graph of Viscosity, the more Viscous the Magma the less ability it has to flow like a liquid (and thus the more likely a plug is likely to form inside a volcano). Image