[Big Digger]

IMHO, I don't believe an Atlantic Ocean tsunami can be generated by collapsing the side of a mountain, say in the Canary Islands, into the sea in the tidal depth zone. There would be a big splash but the energy would dissipate fairly locally in the air/water interface. You would need a deep ocean tectonic displacement, similar to what has just ocurred in South Asia. In the Atlantic, it would take the African Plate slipping against the North American Plate, to displace the amount of water and generate the impulse necessary to power this type of wave. The energy is trapped and travels unseen underwater until it reaches a coastline where it dissipates by breaking in the shallows and flooding over the shoreline. Am I all wet, or what?

[monday]

"There would be a big splash but the energy would dissipate fairly locally in the air/water interface."

I agree with you to a point. I think the tsunami would result when the twenty square mile chunk of rock hit the sea bed. All that water squeezed between the rock and the sea floor would displace a tremendous amount of water. I too am just guessing. I don't know if you are "all wet".

[muffaletaman]

Actually, earthquakes are limited in the size of tsunami they can create by the size of the earth displacement (vertical thrust or subsidence) which occurs.

Huge landslides such as the eventual La Palma event can displace much more water vertically, and thus raise much higher waves, which then propagate in the same manner as the earthquake-generated waves.

Some models show the La Palma wave when generated will be 650 meters high (2130 feet) - but others say it could start as 1 km (3280 feet) or higher. It will still dwarf this past weekend's tsunami after traversing the Atlantic ocean.

http://www.bbc.co.uk/science/horizon/2000/mega_tsunami_transcript.shtml