Supercatastrophe

Then came that supercatastrophe, that curse and blot upon civilization, the great World War.

Source: wiktionary

It may be a vast waterfront fire, like the Staten Island ferry terminal blaze a few years ago that consumed acres of buildings; a supercatastrophe, like the Black Tom explosion; a blazing oil tanker drifting toward a pier laden with explosives; or perhaps a helicopter pilot has dunked in the river, a boat is adrift, or someone has fallen off a ferryboat.

Source: wiktionary

Insurance underwriters very often take the same optimistic view as property owners and in many countries underestimate the long term annual cost for the rare supercatastrophes.

Source: wiktionary