Work out tsunami wave speed instantly with clear inputs, formula shown and shareable results.
A tsunami is a shallow-water wave even in the deep ocean because its wavelength dwarfs the depth, so its speed is sqrt(gd). At 4000 m that is 198 m/s, or 714 km/h - jetliner speed - crossing 1500 km in about 2.1 hours. In 10 m of water it slows to 9.9 m/s, and the energy piles up into height as it does so.
Shallow-water wave speed
v = sqrt(g x depth)
Travel time
t = distance / v
Because slowing compresses the wave: energy flux is conserved, so as speed drops the amplitude rises through wave shoaling.
In deep water its amplitude may be under a metre spread over a 200 km wavelength, so a ship rises and falls imperceptibly over minutes.