"Volcano" Because something burns inside of me.
I would rather have been a terrible storm, a great wave to crush a coastline, a rampaging tornado, or a furious volcano.
I'm sure it was because of volcano activity, people saw fire emerging from the earth and so always had a vague idea that beneath the surface, it was hot. The Phlegraean fields, Vesuvius, Etna etc.
btw does the characterisation of christian hell being hot and underground predate modern knowledge about earth's core and magma layers? was it because people dug deep enough to notice it was hotter? did people directly attribute the eruption of volcanos to something exiting from inside the earth and therefore hell? i haven't read dante's inferno feel like that might have some answers.