Hazards

Tsunami

New Zealand’s entire coast is at risk of tsunami. A tsunami can violently flood coastlines, causing devastating property damage, injuries and loss of life.

A tsunami is a natural phenomenon consisting of a series of waves generated when a large volume of water in the sea, or in a lake, is rapidly displaced. A tsunami can be caused by large submarine or coastal earthquakes; underwater landslides which may be triggered by an earthquake or volcanic activity; large coastal cliff or lakeside landslides; or volcanic eruptions beneath or near the sea.

The three types of tsunami

There are three distinct types of tsunami. The type you encounter depends on the distance you are from the place where it is generated.

  • Distant tsunami are generated from a long way away, such as from across the Pacific in Chile. In this case, we will have more than three hours warning time for New Zealand.
  • Regional tsunami are generated between one and three hours travel time away from their destination. An eruption from an underwater volcano in the Kermadec Trench to the north of New Zealand, could generate a regional tsunami.
  • Local tsunami are generated very close to New Zealand. This type of tsunami is very dangerous because we may only have a few minutes warning.

Tsunami Warnings

Warning messages and signals about a possible tsunami can come from several sources – natural, official or unofficial.

Natural warnings
For a local source tsunami which could arrive in minutes, there won’t be time for an official warning. It is important to recognise the natural warning signs and act quickly.
See the right-hand panel for more information

Official warnings
Official warnings are only possible for distant and regional source tsunami. Official warnings are disseminated by the Ministry of Civil Defence & Emergency Management to the national media, local authorities and other key response agencies. Your local council may also issue warnings through local media, siren and other local arrangements.

Unofficial or informal warnings
You may receive warnings from friends, other members of the public, international media and from the internet. Verify the warning only if you can do so quickly. If official warnings are available, trust their message over informal warnings.

More Information about Tsunamis

For more information on what to do before, during and after a tsunami, visit www.getthru.govt.nz

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