Tsunami Prevention

HELLO EVERYONE. Its a Sunday and im kinda bored. Ive done all my work at home and now its time for some silly thinking.

I have this thought, which all of you might laugh but hear me out first.

I have an idea on how to prevent giant Tsunami waves. Along the coastal line of a continent/country/island, the government should build a 15 meter (judging from the latest waves height in Japan) automatic shield; strong enough to handle the hardest impact of tsunami wave ever recorded in history.

1) How?

Obviously we can't build it ON the beach itself or after the beach. It would be best to build it before the beach, on earth ground for more stability. And of course we won't hide all 15 meters (or more, judging from the Alaska Tsunami waves in 1958 which went up till 914 meters; highest tsunami waves ever recorded in history) of metal shield underground. It will be build with fold-able technology (like the sliding doors in our homes except it goes upwards/downwards).

2) Budget

Yes it sounds ridiculous to build shields in every country considering trillions of miles of shield and the price to pay for. But loosing homes, family and a whole entire city itself cost more than those shield don't you think?

The above is just something i thought of out of no where while sitting on my couch on a Sunday afternoon. After all no one can fool mother nature, can we? Japan builds their buildings base on the anti-earthquake technology which was suppose to defeat quake impact that has ever happened in history but who knows mother nature tops that with a 8.9 mag quake on Friday?

So people read my idea, and if u might, have a good laugh if it is ridiculous but it would be great if the greatest scientist on this planet could figure something out to prevent tidal waves from washing our cities, ain't it? =D