Tsunamis
There’s already a blog devoted to the tsunami. On LiveJournal, mabfan recounts Europe’s worst earthquake/tsunami. For tsunamis in general, see the WWW Tsunami Information Resource.
Don’t think you’re safe on the East Coast. There are several ways it could happen here - if Cumbre Vieje in the Canary Islands drops a huge chunk of itself into the sea, if Portugal has another earthquake like the 1755 terremoto, or if the continental shelf starts cracking up. It could be bye-bye Boston at any time…