In a zombie apocalypse, a widespread (usually global) rise of zombies hostile to human life engages in a general assault on civilization. Victims of zombies may become zombies themselves. This causes the outbreak to become an exponentially growing crisis: the spreading phenomenon swamps normal military and law enforcement organizations, leading to the panicked collapse of civilized society until only isolated pockets of survivors remain, scavenging for food and supplies in a world reduced to a pre-industrial hostile wilderness. Possible causes for zombie behavior in a modern population can be attributed to viruses, bacteria or other phenomena that reduce the mental capacity of humans causing them to behave in a very primitive and destructive fashion.
The Zombies Themselves
Generally the zombies in these situations are the slow, lumbering and unintelligent kind first made popular in the 1968 film Night of the Living Dead. Recent films, however, have refeatured zombies that are more agile, vicious, intelligent, and stronger than the traditional zombie. In most cases of "fast" zombies, creators use mindless human beings (as in Zombieland and Left 4 Dead) instead of re-animated corpses to logically counter the "slow death walk" of Romero's zombies. According to a 2009 Carleton University and University of Ottawa epidemiological analysis, an outbreak of even Living Dead's slow zombies "is likely to lead to the collapse of civilization, unless it is dealt with quickly."
In Max Brooks' The Zombie Survival Guide a Zombie Apocalypse would be classified as a Class 4 Outbreak. This scenario was portrayed in stunning detail in Brooks' later work, World War Z. For a variety of reasons (including those listed above, and also many having to do with our globalized, interconnected, interdependable civilization - see Modern Vulnerability). The Zombie population rose to match, possibly even exceed the human one, on a global scale. Entire cities and nations were over run with the undead, and the uninfected population had to deal with the large scale breakdown of order in a chaotic dystopia. In The Zombie Survival Guide, Max Brooks devotes an entire section to analyzing what measures should be taken to survive the undead world, and possible outcomes.
In an interview with Ain't it Cool News, Max Brooks commented on the fans of zombie apocalypses: "I don't know what's scarier, the fact that zombies could rise or the fact there are actually people out there that can't wait for it to happen. So they can just start loading up with guns and get on their motorcycles..." Brooks also compared the interest in surviving a zombie apocalypse to people preparing for a Soviet invasion of America in the 1980s after the film Red Dawn was released.
- Initial contacts with zombies are extremely dangerous and traumatic, causing shock, panic, disbelief and possibly denial, hampering survivors' ability to deal with hostile encounters.
- The response of authorities to the threat is slower than its rate of growth, giving the zombie plague time to expand beyond containment. This results in the collapse of the given society. Zombies take full control, while small groups of the living must fight for their survival.
Some zombie stories usually follow a single group of survivors, caught up in the sudden rush of the crisis. The narrative generally progresses from the onset of the zombie plague, then initial attempts to seek the aid of authorities, the failure of those authorities, through to the sudden catastrophic collapse of all large-scale organization and the characters' subsequent attempts to survive on their own. Such stories are often squarely focused on the way their characters react to such an extreme catastrophe, and how their personalities are changed by the stress, often acting on more primal motivations (fear, self-preservation) than they would display in normal life
The ultimate fate of humanity is rarely settled to any certainty in tales of a Zombie Apocalypse. This is partly because most Zombie works are very intimate, personal stories between small groups, and it is very difficult to effectively add the large scale military endeavor without the story becoming something else entirely. Regardless of the end result, whenever the Living Dead, or Rabid Infected rise in large enough numbers to disrupt national or global traffic and trade, that scenario is a Zombie Apocalypse. And in case of emergency always be prepared at home or at school...especially at school every badass and wimp for themselves.