All of New Zealand’s coastline is at risk of tsunami. Knowing the warning signs and the right action to take can help save lives. Find out what to do before, during and after a tsunami.
A tsunami is a series of powerful waves with strong current. They can be caused by an earthquake, volcanic eruption, landslide or even a meteorite impact. They can travel many thousands of kilometres across the oceans at speeds of up to 800 kilometres per hour.
Tsunami waves contain considerable energy. They travel much further compared to ordinary coastal waves. Even small tsunami can be dangerous to those in or near the water.
New Zealand’s entire coastline and some of our larger lakes are at risk of tsunami.
Tsunami can flood our shores, causing property damage, injuries and loss of life.
The biggest tsunami in New Zealand are likely to be caused by events close to our shore and can arrive within minutes.
There are three different types of tsunami, depending on where they start.
Distant
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. There will be time for official warning messages.
Regional
Regional tsunami are generated between one and three hours travel time. An eruption from an underwater volcano in the Kermadec Trench to the north of New Zealand could create a regional tsunami. There will be time for official warning messages.
Local
Local tsunami come from very close to New Zealand. In this case, there won’t be time for an official warning. People in coastal areas need to take immediate action.
Remember: Long or Strong, Get Gone.
If you feel an earthquake that makes it hard to stand or lasts more than a minute, move immediately to higher ground or as far inland as possible out of tsunami evacuation zones.
Reduce the impacts of tsunami
Find out your tsunami risk. Your Civil Defence Emergency Management Group has tsunami evacuation zone maps and advice. Make sure you know where to go, whether you are at home, at work or out and about.
Review your insurance regularly. Having insurance cover for your home and contents is important to help you get back on your feet if you suffer damage in a disaster.
Get ready before a tsunami
- Work out what supplies you may need and make a plan together.
- Know your tsunami evacuation zones. Make sure you know where to go, whether you are at home, at work or on holiday.
- Understand the different types of warnings: Natural, Official and Unofficial.
- Regularly practise your tsunami hīkoi (evacuation walk).
What to do during a tsunami or when a tsunami warning is issued
Know the natural warning signs and take action
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.
Drop, Cover and Hold if there is earthquake shaking. As soon as the shaking stops, move immediately to the nearest high ground or as far inland as you can out of tsunami evacuation zones. Even if you can’t get out of your evacuation zone, go as far or as high as you can. Every metre makes a difference.
If you are near a shore and experience any of the following, take action. Do not wait for official warnings.
- Feel a strong earthquake that makes it hard to stand or a long earthquake that lasts more than a minute
- See a sudden rise or fall in sea level
- Hear loud or unusual noises from the sea
Remember, Long or Strong, Get Gone.
This evacuation advice overrides any COVID-19 requirements to stay at home. Stay 2 metres away from others if you can and if it is safe to do so. Wear a mask or face covering only if you can grab one quickly and it will not delay you leaving.
Walk, run or cycle if at all possible to reduce the chances of getting stuck in traffic congestion.
Take your animals with you only if it will not delay you. Do not spend time looking for them and if you are not at home, do not return to get them.
While evacuating, avoid hazards caused by earthquake damage, especially fallen power lines.
Do not return until you get an official all-clear message from Civil Defence.
Official warnings
When tsunami travel across the ocean from far away, we have more time to warn people what to do.
Civil Defence issues tsunami warnings in New Zealand.
Tsunami warnings are published on the National Emergency Management Agency’s website and @NZCivilDefence Twitter channel. Tsunami warnings will also be broadcast on radio and television. An Emergency Mobile Alert may also be issued if there is a threat of flooding of land areas.
Warnings may also be broadcast through:
- siren
- phone
- mobile text
- loud hailer, or
- other local arrangements.
Contact your Civil Defence Emergency Management Group for more advice. They can tell you about the warnings used in your area.
Immediately follow the advice of any emergency warning. Do not wait for more messages before you act.
Unofficial or informal warnings
You might receive informal warnings. Informal warnings could come from:
- friends
- other members of the public
- international media, and
- the internet.
If the warning seems trustworthy, consider evacuating. Check the accuracy of the warning once you have evacuated or en route if it won’t slow you down.
If official warnings are available, trust their message over informal warnings.
What to do after a Tsunami
Only return home once you are told it is safe to do so.
Listen to the radio or follow your Civil Defence Emergency Management Group online. They will give you information and instructions.
If there was an earthquake, expect more shaking. More earthquake shaking may generate another tsunami. Be prepared to evacuate.
Stay away from coastal water, tidal estuaries, rivers and streams for at least 24 hours after any tsunami or tsunami warning. Even small waves create dangerous currents.
Avoid areas impacted by the tsunami. You might hamper rescue and other emergency operations and be at further risk from the residual effects of tsunami flooding.
Help others if you can, especially people who may need extra help.
If your property is damaged
- Do not do anything that puts your safety at risk or causes more damage to your property.
- Contact your insurance company as soon as possible.
- If you rent your property, contact your landlord and your contents insurance company.
- Take photos of any damage. It will help speed up assessments of your claims.
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