[dr_lew]

You lost me on the math! But one thing - the tsunami (either due to submarine EQ or landslide) doesn’t show much if anything on the water surface mid-ocean. But it is the shallowing of the water at the shelf that concentrates the energy. Is your math more for waves at the surface?

I think that's correct, since a wavelength much less than the depth is what defines this term ( i.e. surface wave.) Tsunamis originate from broad upheavals of the ocean floor, and have a long wavelength and high speed of propagation.

A landslide can produce a high amplitude, but not a long wavelength, as far as I understand it.

[21twelve]

I guess like dumping a rock into the kiddie pool produces a different type/size of wave than trying to lift one edge to move the pool produces a whole ‘nother kind of wave. (That usually ends up with your shoes getting wet).