As when a heavier oceanic or continental plate is subducted under the lighter plate the overlying plate created pressure and the lower plate experiences a force that is a type of the slab pull and slab push.
That leads to this the huge killer waves or the Tsunamis are created and these waves tend to be produced by the submergence and the occurrence of the earthquake and thereby the resultant volcanic eruptions also along the boundaries.
<u>These waves can be as high as the tallest building and cause heavy destruction and flooding in the coastal lands.</u>