Is the water pressure below ocean waves constant?

[olivermsun]

Thanks, CWatters.
Here's another useful resource as well: http://web.mit.edu/1.138j/www/material/chap-4.pdf

 

[sophiecentaur]

FWIW, the vertical displacement due to tsunamis traveling in the deep ocean is typically very small.

It's down to the total volume of water displaced, I suppose. If the deep water height is 1m and the wavelength is 1km then it stands on its end when entering shallow water. You can easily get tens of metres of height.
But, apart from the dimensions, the tsunami has to behave the same as small waves breaking on the shore. Water waves are only different at the very small scale, where surface tension dominates (capillary waves) there is no difference in the physics of straight 'gravity' waves.
Having observed many bow waves from ships as they meet a shallow shore, I have noticed the very same effect that tsunamis cause - once launched, the moderate bow wave carries on for a great distance and then peaks as it reaches the beach etc. etc.. Interestingly, the dissipation is not inverse square because the spreading is not over a sphere and it's not even 1/r because the wavefront of an established bow wave is more or less a straight line. I like to think in terms of Huygens construction (personal observation but justified, I think). A tsunami can be generated by a large aperture source like half an island appearing or disappearing so I imagine the source can be looked at as several wavelengths. Hence less dispersion of energy.

 

[pieselsoft]

If you are stationary say 10m below the ocean surface does the water pressure at your location vary with the waves.

For example:

When a wave crest is above you than means perhaps 12m of water is above you.
Then a few seconds later a trough is above you so only 8m of water is above you.

So you might expect your pressure reading to be going up and down with the waves?

No. It is rather complicated, because you have to include dynamic pressure, and not just the hydrostatic pressure (use Bernoulli's Equation). It's not static, if there are waves, and dynamic pressure comes from the fact that the water is moving and accelerating, which requires forces/pressure. How it behaves depends on the depth of the water. See here, e.g. http://web.mit.edu/2.016/www/handouts/Free-Surface-Waves.pdf