Marwoode..you have raised an interesting issue....It certainly aroused my interest so I did a bit of googling!!
Lihir island sits right on the Bismarck tectonic plate in the Pacific ring of fire (PRF).....this region has many earthquakes.....
Given that New Zealand and Japan lie withing the (PRF) and have just had earthquakes it would not be a surprise if one occured. They all appear to lie on the same fault line...
However, I think a good deal of NCM's price slide has to do with the price of gold and the market in general....