A tsunami is a series of waves created when a body of water, such as an ocean, is rapidly displaced. Earthquakes, mass movements above or below water, some volcanic eruptions and other underwater explosions, landslides, underwater earthquakes, large asteroid impacts and testing with nuclear weapons at sea all have the potential to generate a tsunami. The term tsunami comes from the Japanese meaning harbor. A tsunami has a much smaller amplitude (wave height) offshore, and a very long wavelength (often hundreds of kilometers long), which is why they generally pass unnoticed at sea, forming only a slight swell usually about 300 mm above the normal sea surface.
The effects of a tsunami can be devastating due to the immense volumes of water and energy involved. This can be very damaging to Vanuatu’s settlements as most of them are located on flat plain coastal areas right across the island group.