This is because I’d deep ocean,tsunami waves may appear only a foot or so high.But as they approach the shoreline and enter shallower water they slow down and begin to grow in energy and height.Since the tops of the waves move faster than the bottoms so it causes them to rise faster.So...if a tsunami is in deep waters it does not really hit the shore and splash around to hurt anyone or anything or any people.It is fine because it’s in the middle of the ocean and not on the shoreline.I hoped I helped even a little bit :3
Any numbers to work with?
