This word originally meant a flood. Since the source is Late Latin and derived from a Greek word, its not a stretch to believe that this started in the 15th century from the story of Noah. The for a flood derived from Latin is inundation.
It's striking that cataclysm now refers to the destruction caused by the flood while inundation refers to the agent of the flood. Many Christians believe that the first cataclysm came by means of water while the final cataclysm will come by means of fire. The word cataclysm can refer to both events.
Inundation, however, appears to be tied specifically to water. Conflagration relates to fire. Miasma doesn't quite relate to being overcome by a gaseous substance, but it is foreboding enough for me. 🙂