A disaster movie is a movie that has an impending disaster (e.g. an asteroid collides with Earth) as its subject. They typically feature large casts and multiple plotlines, and focus on the characters' attempts to avert, escape, or cope of the aftermath of the disaster. One major character, several minor characters, and scores of extras typically die before the story is resolved.
Disaster movies are nearly as old as film itself. D. W. Griffith's Intolerance (1916) has disaster elements, as do 1930s dramas such as San Francisco (earthquake) and In Old Chicago (fire). Science-fiction movies such as When Worlds Collide routinely used disasters as plot elements in the 1950s and early 1960s. The heyday of disaster movies began in 1970, however, when the success of Airport generated a flood of "all-star-cast-in-peril" stories.
Airport itself qualifies as a disaster movie only in retrospect. It is closer in tone and construction to The High and the Mighty or Zero Hour than to the full-blown disaster films that came after it. The disaster-movie cycle of the 1970s, really began with The Poseidon Adventure (ocean liner capsized by tsunami) in 1972, and continued with similar movies such as The Towering Inferno and Earthquake. The genre was beginning to burn out by the mid-1970s, when movies like The Swarm and Meteor were being produced more and more quickly with less production effort and less impressive casts.
The disaster movie genre revived, briefly, in the mid-1990s--perhaps because new special effects techniques made more spectacular disasters possible. The most spectacular products of this brief revival were "Jurassic Park" (1992) and a pair of extraterrestrial impact movies Deep Impact and Armageddon, both released in the summer of 1998.
Notable disaster movies