The word ‘tsunami’ is of Japanese origin. When you look it up in a dictionary, you will find that it means ‘a great sea wave produced by submarine earth movement or volcanic eruption’.
A megatsunami is the superlative of this awesome expression of power that nature can create, and has catastrophic consequences.

When Carl Wittrock completed this composition not many such big earth movements had occurred, but since then we have become all too familiar with the disastrous consequence...