Surviving an extinction-level event would necessitate a fully self-sufficient colony, but could such an underground base keep on sustaining itself, let alone gr

Surviving an extinction-level event would necessitate a fully self-sufficient colony, but could such an underground base keep on sustaining itself, let alone grow and develop for as long as it takes for the dust to settle, so to say? The timescales could be very long, I have no idea how long but possibly thousands of years could be too short. A self-sufficient offworld colony is the best bet for normalcy and sounds like an overall faster and workable way for bootstrapping things again. Also, the technology developed as a precursor for offworld colonies would likely aid in things like detecting and diverting asteroids. Colonizing the difficult places on the Earth, such as seabeds, sea bottoms and places deep underground, would be a good way to practise for the everyday life offworld (can't go out just like that, all food farmed indoors, strict trash recycling regimes, etc.) but I don't think it would be equivalent as a "backup".