cataclysm
     n 1: a sudden violent change in the earth's surface [syn: {catastrophe}]
     2: an event resulting in great loss and misfortune; "the whole
        city was affected by the irremediable calamity"; "the
        earthquake was a disaster" [syn: {calamity}, {catastrophe},
         {disaster}, {tragedy}]
Source: WordNet® 2.0