VDweller
Look, Ma! Two Heads!

First, the word "apocalypse" is ancient and it fits much better into a pseudo-Roman setting than into anything modern.
apocalypse
noun
1. a cosmic cataclysm in which God destroys the ruling powers of evil
2. the last book of the New Testament; contains visionary descriptions of heaven and of conflicts between good and evil and of the end of the world; attributed to Saint John the Apostle
Second, let's take the Deluge, for example. Wouldn't you agree that a post-Deluge society could be easily described as post-apocalyptic? Same goes for Atlantis, if we stick with the legends and assume that it was a reasonably advanced (comparing to their neighbors) society which was suddenly destroyed in a single night, forcing the locals to flee to nearby continents and start from scratch.
apocalypse
noun
1. a cosmic cataclysm in which God destroys the ruling powers of evil
2. the last book of the New Testament; contains visionary descriptions of heaven and of conflicts between good and evil and of the end of the world; attributed to Saint John the Apostle
Second, let's take the Deluge, for example. Wouldn't you agree that a post-Deluge society could be easily described as post-apocalyptic? Same goes for Atlantis, if we stick with the legends and assume that it was a reasonably advanced (comparing to their neighbors) society which was suddenly destroyed in a single night, forcing the locals to flee to nearby continents and start from scratch.