Tsunami Travels

  • A tsunami behaves as a shallow water wave.
  • Tsunami's travel in much the same way as your garden variety, wind-propagated water waves: with some combination of transverse and longitudinal movement.


  • The main differences between tsunamis and wind-generated waves is the wavelength and period of the waves. Regular ocean waves have a wavelength of about 150m, and a period of about 10s. Tsunamis, on the other hand, have wavelengths in excess of 100km, an amplitude of 1.5m and a period on the order of an hour.
  • The propagation velocity of a tsunami is equal to the square root of the acceleration of gravity times the depth of the water (v = (g*d)^1/2). So at a depth of about 4000m, a tsunami will travel at about 700km/hr. Take a look at this animation: http://www.ess.washington.edu/tsunami/movies/globe.mov
  • The energy of a tsunami can be expressed as: where =the density of water, g=the acceleration of gravity, =the wavelength, L=distance traveled, and a=the wave amplitude.
  • A good average for the energy in a tsunami wave is 2 PJ (2x10^15 J).

Penn State Department of Geosciences

  • In the open ocean, a tsunami wave will appear little if any different from other waves. If a tsunami passes by a ship, the crew will not notice it.