This is one of the slides from Larry Braile's PowerPoint presentation.
Tsunami wave propagation characteristics – note that as water depth becomes smaller, waves slow down, become shorter wavelength, and have larger amplitude.
Larry asks: When the water is 10 m deep, what is the separation of the waves in minutes?
Here's my answer: The formula relating the period (T) with velocity (V) and wavelenght (L) is:
T = L / V
for 10m depth, T = 10.6/36 = 0.29 hours (about 18 minutes)
From a trough, the water would rise for 9 minutes and then fall for 9 minutes to the next trough.
The velocity is given by the squareroot of (water depth X the acceleration of gravity)