Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

How is tsunami speed derived?

  1. Jan 12, 2005 #1
    I read that the speed of a tsunami is given by

    c = sqrt(G * d)

    where G is the gravitational constant 9.8 m/sec^2 and
    d is ocean depth in meters.

    How is this derived? I had always thought that wave speed was a constant depending only on the medium.

    Also, is there some fundamental mechanical difference between a tsunami and a "normal" surface ocean wave?
  2. jcsd
  3. Jan 12, 2005 #2
    Do you also know the formula for the height of the wave. (Of course in respect to the clifs stepping.)
  4. Jan 12, 2005 #3
    Hello lagrange,

    The behaviour of tsunami is the behaviour of shallow-water waves.
    Therefor the velocity of the waves is given by the equation for the shallow-water phase- and group velocity.

    Here you'll find the linear theory of ocean surface waves:

    The shallow-water velocity equation (16.8) and (16.11) in this paper are derived using the equations (16.5)and (16.6).

    More about ocean waves and tsunami:
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook