Ditto what Pathfinder said (thank you!).
In the original outline for season 1, the final episode was supposed to address "civil unrest"--the kind that happens during large-scale natural disasters and such. As the shooting of the season progressed, we realized that the logistics of tackling that were beyond our scope that that time, so we stuck with home/personal defense.
When the show aired, the response was very positive. In addition to wanting more, viewers also asked specifically for topics related to personal preparedness. After giving it some thought, OC decided to "spin off" TBD: Survival as a distinct program series. The formula now is 13 episodes of TBD (aired Jan-June) and 7 episodes of TBD: S (aired July-Dec).
I hope this helps. Look for the new season of TBD:S to start soon--probably on 29 June.
Stay safe,
Mike