I built in Maya a thick curved volumetric atmosphere with flashing and randomly animating point lights inside them to allude to lightning. I used the Magellan satellite image of the volcano Sapas Mons to displace an environment, and then added detail in a shader from reference imagery of Hawaiian volcanoes.
I simulated a pair of dynamic volcanic plumes based on notes and feedback from planetary scientist David Grinspoon.
They were surrounded by a series of smoky particle effects and 2D fluids to represent the surfaces of the magma pools. A blobby particle simulation at the center made the pools feel alive.
The effect of these many effects was a pretty dynamic cinematic sequence!