The term ‘tsunami’ (harbour wave) comes from Japan where the phenomenon frequently occurs. When an underwater quake or any other cause suddenly sets a great depth of water into motion, it causes a gigantic wave to form. In the open sea, the undulation cannot be seen. However, when it hits shore, its height increases, submerging the coastline and destroying everything it encounters.

The main events preceding the Tsunami are illustrated here:

• undersea earthquake.
• propagation of the wave.
• arrival on coasts.