Suggested rewording for intro screen:
"The severance from Earth was nothing but a cataclysmic catastrophe"...
A: Change to, "The severance from Earth was nothing short of a cataclysmic catastrophe"... (as it was indeed short of that, by a very long margin.)
or B: Remover the near redundancy.
The near redundant usage of both "Cataclysmic" and "Catastrophe" indicates an event that was:
Natural in origin and extremely violent, causing tremendous physical damage, and again,(redundantly), a disaster.
As no violence or damage resulted from the gate itself turning off, but rather was a direct result of subsequent events; a wholly better phrasing for your intent might be, "The severance from Earth proved to be an immanent social calamity"; which would mean that the severance from Earth was the direct cause of a subsequent total upheaval of the social order, without an emphasis on physical destruction.