Whenever there is an earth tremor in this area I always wonder if the aptly named "Earthquake Passage" in the Top Level Extension of the Coniston Copper Mines has collapsed into the stope. Large, constantly extending cracks in the floor, huge splits and gaping holes in the tunnel walls.
During a survey with the BGS I took them there and the comment was "lets leave NOW!!"
Always changing, not a permanent feature for sure.
Jeff