IFRC

Geophysical hazards: Tsunami

Definition and characteristics

A tsunami  is a series of waves caused by a rapid displacement of a body of water (ocean, lake). The waves are characterised by a very long wavelength and their amplitude is much smaller offshore. The impact in coastal areas can be very destructive as the waves advance inland and can extend over thousands of kilometers. Triggers of a tsunami can be: earthquakes, volcanic eruptions, mass movements, meteorite impacts or underwater explosions. The Japanese term for this phenomenon "tsunami" ("Wave in the port" in Japanese) , which is observed mainly in the Pacific, has been adopted for general usage.

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