I’m sure we have all seen the horrific footage of the Japanese Tsunami pouring over sea-walls and going on to devistate cities. In some cases, those cities had truly massive sea walls - which did not save them, as the tsunami was simply too large.
My question is this: if the sea wall is marginally lower than the height of the tsunami, would it offer some protection? Or is it more like a dike that is too low - the sea floods in and it does very little good?
Say the sea wall was 8 metres high and the tsunami was 10. Would the wall do any good, minimizing the amount of water that gets in, or must the wall be higher than the tsunami to have protective effect?