I am listening to a song about volcanoes. It is called "Pyroclastic Annihilation" performed by a brutal deth/thrash metal band called "Demolition Hammer". It is from their album "Epidemic of Violence" released in 1992. The song is: https://www.youtube.com/watch?v=S_7qqsVioxo the full lyrics can be found here: https://genius.com/Demolition-hammer-pyroclastic-annihilation-lyrics
I have come across a term I do not understand.
Seas of boiling mud
Subrelluric forces exploding violently
Pyroclastic matter intense velocity
Is the word "Subrelluric" a geological term? If yes what does it mean exactly? What are Subrelluric forces? What do they do amidst a volcanic eruption? I couldn't find anything on the web. Perhaps this is an extremely advance term not usually used in the public world?