Geology. Of or relating to a sudden, violent, geological action; catastrophic, cataclysmic; spec. relating to or designating a volcanic eruption…

Of the nature of, or belonging to, a catastrophe: esp. in the history of the earth or the universe.

Of, pertaining to, or of the nature of, a cataclysm.

= cataclysmic, adj.

Cataclysmic.

Referring to, dealing with, catastrophes; also = catastrophic, adj.

= cataclysmal, adj.