What is a tsunami wave?

Answer 1

Tsunamis are very different from ordinary waves on the ocean surface, even very large surface waves. When earthquakes on the ocean floor cause massive and extremely rapid upward or downward shifts of the ocean floor itself, this results in a shift of the entire water column above it. It is the movement of the entire water column from ocean floor to surface that makes a wave a tsunami. You can see that they contain a huge amount of the energy released by the earthquake. Surface waves can affect water going down for several meters, but even in the heaviest seas you could find a water depth where there is little or no movement caused by the waves above.

a giant stock wave