A tsunami is a series of waves caused by large earthquakes. All of New Zealand’s coast line is at risk of tsunami. A tsunami wave can grow to become a fast moving wall of water. 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. Move immediately to the nearest high ground, or as far inland as you can. Walk or bike if possible. Sometimes tsunami travel across the ocean from far away and we have more time to warn people what to do.



Tsunami warning sign

Tsunami is a Japanese word meaning ‘harbour wave’. A tsunami is a series of fast travelling waves caused by a large disturbance in the sea or on the ocean floor. An earthquake, landslide, volcanic eruption or meteorite can cause the disturbance. The waves can be separated by as much as an hour apart. They can travel many thousands of kilometres across the oceans at great speeds of up to 800 kilometres per hour.

A tsunami may not be noticed as it crosses deep oceans, but it loses speed and gains height when it reaches shallow water. Large waves up to 15 metres or more in height can come crashing onto the land. The effects can be worse in narrow bays and inlets.

Tsunami waves appear either as rapidly-moving tides with very strong currents that can wash people and objects out to sea, or as large breaking waves that can cause major damage when they hit the shore.

Tsunami can be caused by big earthquakes in or near New Zealand. If you feel an earthquake that lasts longer than one minute, or one that is so strong it is hard to walk around or stand up, a tsunami could follow it. Sometimes when tsunami waves arrive on shore it looks like the water has been sucked out before it rushes back in, or the waves make unusual noises like a jet engine. However, these don’t always happen. 

If you are at the coast and experience any of the following:

  • Feel a strong earthquake that makes it hard to stand up, or a weak rolling earthquake that lasts a minute or more
  • see a sudden rise or fall in sea level
  • hear loud and unusual noises from the sea.

Move immediately to the nearest high ground, or as far inland as you can. Walk or bike if possible.

Remember long or strong, get gone.

What do we do before a tsunami?

  • Talk with your family and prepare an emergency plan.

  • Your local Civil Defence Group has tsunami zone maps and regional advice. Make sure you know where to go, whether you are at home, at work or out and about.

What do we do during a tsunami?

  • Move immediately to the nearest higher ground, or as far inland as you can. Walk or bike if possible.

  • Do not go sightseeing. Never go to the shore to watch for a tsunami.

  • Stay away from at-risk areas until the official all-clear is given.

What do we do after a tsunami?

  • Stay calm.

  • Listen to, and follow, instructions from adults or the radio.

  • Help others who may need it, if you can.

Home learning

IzzyIdentify safe places close to your home and school by checking your local Civil Defence group’s tsunami zone maps.

Ask an adult to help you take a picture of a safe place that can be shared with your neighbours, class, etc.

Make a plan with your family to get through an emergency. Think about the things you need every day and work out what you would do if you didn't have them. 

Make your plan  – print it out, stick it on the fridge and make sure everyone knows the plan.