Yes, probably, and it's also true that a "Planet-killer" asteroid is likely to hit us. The question is when, which we just don't know. Although Geologists may say that a tidal wave is likely to occur "soon", from their perspective that means "at some point in the next few million years". Similarly with the asteroid.
It was on Horizon a few years ago. The theory is that a big slab of rock on one side of one of the Canary Isles is gradually cracking away from the rest of the island due to volcanic action, and it might slip off in one big whoosh sometime. The aim is to make sure it crumbles gradually, rather than in one swell foop.
This scares the hell out of me, I watched that Horizon episode (and God, I wish I hadn't) and it actually gave me nightmares. The same with that bloody film 'Deep Impact', everyone I watched it with thought it was rubbish, but I was so scared I didn't notice.
On the concept of one teetering bit of Volcano causing such widespread destruction... Not wishing to scare anyone! but A little push with Explosives wouldn't be A hard to concieve idea for the Terrorists of the world. If they haven't thought of it the Scriptwriters of Hollywood probably have... Maybe for the next 'Bond' saves the world tale!