After fighting with the Mayor, the cavernous lower levels of the Crater will begin to collapse. The player must back track through the Crater and make his/her way back to the surface while fighting freshly spawned radscorpions, raiders and radbugs. The cave in itself poses no threat to the player, the falling rock animations are just for show and make the whole thing seem more real. The rocks don't actually harm you even though they seem to fall directly on you. Once you get within sight of the elevator back up to Carbon you will receive a message telling you that you've earned 200 experience points for escaping the crater.