I never thought that the long continential shelf would serve as an effective barrier to a megatsunami. I was just wondering about what effect it would have on the wave's energy. A long gradual rise might possibly reduce the energy somewhat, but probably not nearly enough to collapse the wave. On the other hand, it might just make it worse.

I'd love to see the results of some good simulations - and I'd hate to be in the neighborhood if one of those bad boys came ashore. Some of the articles I've seen on the possibility (probability) of a megatsunami caused by the volcano collapse in the Canary Islands state that the wave might take out everything within 20 kilometers of the shoreline. When you look at the population that lives within 20 KM of the eastern seaboard, chances of a successful evacuation even with several hours of warning seem pretty slim. The death toll could be in the millions and the damage in the trillions.