Scientists have discovered a massive tear in the tectonic plate off the coast of Vancouver Island. This 'rip' suggests that the northern end of the Cascadia Subduction Zone is actually starting to shut down. The CBC's Johanna Wagstaffe investigates what this discovery might mean for the 'big one' off the coast of Vancouver Island. »»» Subscribe to CBC News to watch more videos: http://bit.ly/1RreYWS For breaking news, video, audio and in-depth coverage: https://www.cbc.ca/news Follow CBC News