Tsunami - what are our risks?

New Zealand’s entire coast is at risk from tsunami. The biggest tsunami in New Zealand are likely to be caused by events close to our shore and could potentially arrive within just a few minutes. For beaches or in low coastal areasthis could happen after a severe earthquake, without an official warning being issued. In some cases, a relatively weak, rolling earthquake with a long duration could be followed by a large tsunami.

The tsunami danger period can continue for many hours after a major earthquake. Tsunami also may be generated by very large earthquakes far away. Tsunami waves can travel thousands of kilometres and still be big enough when they arrive here to cause loss of life and damage. The map below gives an approximate travel time for waves across the Pacific Ocean.

travel timesImportant things to consider

  • A tsunami consists of a series of waves, and the first wave may not be the largest.
  • There may be many waves separated by up to an hour, or more.
  • Tsunami can travel around corners and inundate what appear to be sheltered areas.
  • All areas of the coastline will not be impacted equally. There can be a large variation in run-up and impact over short distances along the coast.
  • Tsunami waves can travel up streams and rivers with damaging waves extending farther inland than the immediate coast. Once they travel over land, tsunami pick up debris, can knock down buildings and have enormous destructive force.
  • Harbours, bays and inlets often amplify tsunami waves.

Tsunami brochure (406kb PDF)

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