The Japanese call them "tsunamis", meaning "harbour waves", because they reach a sizable height only in harbours.
日本人称其为“海啸”,意思是“港湾浪”,因为它们只有在港口才能达到相当高的高度。
3
As the Roman Empire grew, the Romans needed to take control of the seas and for this they needed to build harbours capable of holding a fleet of ships.