[Strategerist]

Correction, the tsunami wave was travelling at 400-600mph, not a mere 150.

You're even more wrong than the original poster.

Only in the absolute deepest parts of the Ocean (miles deep) do tsunami waves travel at 400 mph....actually, because of the shallowness of the water between the origin fault and Thailand, this particular wave likely never even got close to 400mph.

The actual wave once it's visible from shore and hitting shore is traveling at most 20-40 mph. That's plenty fast.

[Lexinom]

That's what I'd read, too, about tidal waves. Kinetic energy is converted from one form to another - from speed in a free ocean to height near land as the free volume decreases with the approaching shore. Fluid dynamics.

[WildTurkey]

The actual wave once it's visible from shore and hitting shore is traveling at most 20-40 mph. That's plenty fast.

The shallow water velocity is given by:

c = (g * d)^1/2, where g = 9.8 m/sec² and d = depth in meters.