The capital of Blatrice is located underground where it is warmer and safe from avalanches. The entrance appears to be just part of the scenery to prevent against invasion, whether by razorbacks or otherwise. If that fails, they will activate machines that can cause avalanches. It has enough supplies and airholes to last for a year or more under siege. If that fails, they will use their mech militia, an armed force as cold and merciless as the ice surrounding it.