After watching Tohoku tsunami I learned better how it damages shores.
The tsunami wave is not bidirectional as normal waves, it is not too high or too fast, but it is thicker than regular sea water with the dirt of deep sea and strong in one direction.
Probably a sudden geographical shape change under the sea makes movement of water mass towards one direction, towards land, suddenly arosen bump of an undervolcano or something else might block the wave's movement towards deeper sea.
If someone watches the sea from the first floor of a building, notices that the horizon view is restricted because of the swelled sea. For example if there is an island in the distance at horizon, because of the swelled sea, the island can not be seen suddenly any longer. From a higher place with binoculars it is easier to notice that Tsunami is coming.
Figure a. Figure b.
At above figures, I drawed a model of coming wave appearance from the second floor of a building to depict what I understood from the tsunami videos I watched.
I watched a small tsunami from the fourth floor of my house to understand that it is a weird wave with a whitish line over a calm sea.
A video frame at below documentary video reminded me the small tsunami I once watched, experienced.
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This video was a documentary of Tsunami, not only how a deadly wave came but also; saddining event of lives.
It sads me each time, I am removing it.
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It seems some Tsunamies can be known at least some seconds earlier before its damage, a ready waiting helicopter probably could do something in future, but earthquakes are more difficult to have any second to do something.
No doubt, nature is full of unpredictible changes making risky any location; but, although I am a long distance swimmer/long hours open sea swimmer; I never stay too close, long hours, to big seas, oceans.
If even small earthquake waves pull of the dirt from undersea; swimming in such a thick water is not safe/easy. In general, unusual dead plants from undersea dirtying seawater signals to me that something weird is going on undersea faults.
Each geographical location is risky differently; some has frequent dangers, some has infrequent but giant dangers.
At below video a wave from Indian Ocean is seen. I could not find the details, but my gut tells me that this wave was the first small tsunami, the deadly Tsunami was the second that arrived after this wave.
The interesting fact is that even if the wave was giant; its speed would not be higher and probably would look like same speed of the wave as seen on the below video .
