north-west lies a potential killer, a 700 million long geological fault line called the kerr cascadiasubducti, on zone. the big one. it lies far out to sea. hidden beneath the waves. the waiting earthquake. >> i try and look as it could happen any day >>> this man is a regional manager for the federal emergency management agency in the pacific north-west. one of these earthquakes could be a monster. >> i think people are just not mentally or physically prepared to think about how bad something that large can be. >> the earthquake is supposed to be about a 9.0, maybe 9.1 earthquake which is going to rock and roll everything around here for three to five minutes >>> chuck wallac is for greys harbour county on the washing coast. >> they believe the biggest wave we will have is 22 feet in this area here. however, there is a plus and minus 30% on that. so it could be 30 feet high. you're not only getting went wave but multiple waves >>> all around the coast of the pacific sew shan there is tension where the plate slides under, colonel ideas with and sticks on the technical tonic-- techtonic plaits