The Great Cataclysm is the name given to an apocalyptic event which occurred in Final Fantasy Blackmoon Prophecy. Residual effects of it are felt even an entire century later in the sequel, Final Fantasy Blackmoon Prophecy II.
Early in the second part of Final Fantasy Blackmoon Prophecy, Malacore is preparing to bring about the Blackmoon Prophecy when the Archareons, a race that oversees the stability of the Esper World and Gaia after their unintentional linking many centuries ago, confronts Malacore. They insist that, if they merge the worlds, they will be exerting enough magic to be able to disrupt the casting of the Blackmoon Prophecy. While Archareon Leader Gylfi says that merging the worlds would cause a catastrophic number of deaths, it would still pale in comparison to how many would perish if the world was plunged into a frigid and permanent eclipse by Malacore. They go forth with their plan and merge the worlds.
After Vahn Vainstrong awakens a full year later, he finds the world in a vastly different shape than it had been before. Numerous towns were wiped off the face of planet entirely. Towns that were lost in the Great Cataclysm are Branch, Daguero, Falgabard Port, Lantz, Lindblum Castle, Palumpu and Trei. New towns that appeared from the Esper World included Auslen, Clestance, Darnecles Castle, Garamonde, Vilaheim and Visage.
The effects of the merging proved to be entirely permanent and, after the defeat of Zeul, the essence of the Crystals of Element returned to the planet. Despite the severity of the Great Cataclysm, the defeat of the man who had ultimately been behind everything triggered what appeared to be a new era of stability for the merged world.
Between Final Fantasy Blackmoon Prophecy and Final Fantasy Blackmoon Prophecy IIEdit
Only a few short years later, peculiar earthquakes regularly started to rattle parts of Gaia. These tremors would occasionally intensify, gaining enough force to sink lands. Over the next hundred years, many lands would collapse into the sea and each kingdom would experience the loss of several towns.
Devoutly religious individuals sensing a new opportunity seized the chance to claim that the sinking of lands was being caused by an entity they dubbed Graviton. According to soon formed Church of Graviton, their deity was a relic of old times seeking to return the world to its original and pure state prior to when the worlds merged.
The Church of Graviton continues to promote the belief that Graviton is responsible for the residual earthquakes. Geologists and scientists dismiss the Graviton worshippers as fanatics, though they still cannot find scientific evidence to support the belief that the earthquakes are indeed long lasting side effects of the Great Cataclysm. Plans to venture to the Underworld to study tectonic activity have not yet been finalized to the the inhabitants of the Underworld violently shunning outsiders since the Great Cataclysm occurred.
As more land sinks, the Church of Graviton insist that their god's plan is being realized. With the Espers turning against humanity, the Church of Graviton supports the idea of defeating the Espers, as they are not originally of Gaia and are therefore deemed a taint that must be eliminated in order to help the world return to a pure state.