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  • Tsunamis are unique in their destructive power, but they share many features with other ocean waves. Learn how the two wave types differ, and how ocean waves of all kinds affect New Zealand’s coast.

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    Tsunami hazard zone warning sign

    This tsunami sign can be seen around the world, showing people where tsunami evacuation points are and zones where tsunamis are a hazard.

    Ocean waves are a powerful force in the lives of New Zealanders. We like to surf them and swim in them – yet we are also vulnerable to the power of ocean waves. In particular, coastal New Zealand is at high risk of severe flooding by a tsunami.

    Several tsunamis – particularly those in South-east Asia (2004), Sāmoa (2009) and Japan (2011) – have focused attention on the destructive power of these waves. New Zealand researchers are actively working to understand how a large tsunami would affect our coast. Find out more about the work of:

    Key science concepts

    For all their destructiveness, tsunamis share many features with surf waves and other water waves. In fact, waves of all kinds (such as water waves, sound waves and electromagnetic radiation) share several fundamental characteristics that can help us understand why they behave the way they do. Waves transfer energy and shoaling converts the kinetic energy in a tsunami wave into potential energy. Shoaling is one reason why tsunamis cause so much damage to coastal areas.

    Rights: The University of Waikato Te Whare Wānanga o Waikato

    Tsunami shoaling

    In deep water, a tsunami moves very fast and has a long wavelength and a small amplitude. As it enters shallower water, it slows down and the wavelength decreases. This causes the wave to become much taller.

    Use a tsunami lens to learn more about the nature of science. Dr Willem de Lange gives his personal insights about scientific inquiry and what it means to 'do science'. Then check out some of the measuring instruments Willem and others use when observing the natural world.

    Take up the challenge

    Student activities include:

    Useful link​​​​​​s

    News article about how ancient tsunami have been mapped in a new interactive project. The New Zealand Palaeotsunami Database was compiled from old records by the National Institute of Water and Atmospheric Research (NIWA).

    The Ocean Today website has a series of videos on tsunamis from the National Oceanic and Atmospheric Administration (NOAA).

      Published 2 May 2011, Updated 3 August 2018 Referencing Hub articles
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