Tsunami

Tsunami (津波 Japanese big wave in port), often incorrectly called a tidal wave, is a series of massive waves that occurs after an earthquake, seaquake, volcanic activity, slumps or meteorite impacts in or near the sea. Since the constant energy of the tsunami is defined by height and speed, its height increases once its speed is reduced when the wave approaches land. The waves travel at high speed, unnoticed while travelling through deep water, but raising to a height of 30 metres and more. Tsunamis can cause severe destruction on coasts and islands.

Many cities around the Pacific, notably in Japan, have warning systems and evacuation procedures in the event of a serious tsunami. Tsunami are often predicted by various seismologic institutes around the world and their progress monitored by satellites.

Evidence shows that megatsunamis, which are caused by whole islands collapsing into the ocean, are also possible.