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.
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, 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.
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.
Remember, Long or Strong, Get Gone.
Drop, Cover and Hold during the shaking. Protect yourself from the earthquake first.
As soon as the shaking stops, move immediately to the nearest high ground, out of all tsunami evacuation zones, or as far inland as you can.
Listen to and follow instructions from adults or the radio.
Help others who may need it, if you can.
Find out more about what to do before, during and after a tsunami.
Identify safe places close to your home and school by checking your local Civil Defence group’s tsunami evacuation 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.
Find out about past tsunami that have happened in your region.
Tsunami 101 is part of a series of natural disaster videos produced by National Geographic.
A useful site with animations showing the movement of tsunami waves.
Watch this video from GNS Science explaining how tsunami are formed and the damage they can cause.
A New Zealand perspective on tsunami from Te Ara, the Encyclopedia of New Zealand.
STEM-Works have a series of learning experiences that focus on floods and tsunami.
Learn about shoaling and how it works.
Find information about tsunamis that have reached the coastline of New Zealand since humans arrived in this land until the present day. The database is the work of historical seismologist Gaye Downes of GNS Science who collected reports of tsunamis around New Zealand and, in many cases, carried out research to determine parameters of the source, travel time and impact associated with each event.
During the 2020 COVID-19 lockdown, GeoNet asked the public for questions they have always wanted to know the answers to on earthquakes, volcanoes, landslides and tsunami. This YouTube playlist is a series of short videos answering these questions.
Earthquakes, floods, landslides, storms, tsunami and volcanic activity can be frightening because they can strike at any time and often without warning. Explore the types of emergencies below and learn better ways to prepare.