Tsunamis

Red zone

The red zone includes beaches, estuaries, lagoons and river mouths. These are the areas most likely to be affected by a tsunami and that would experience the highest water depths and strongest currents.  This area can be affected by any tsunami, including small tsunamis that are unlikely to flood land but that cause strong surges or currents in the water.

You should leave this zone immediately if you:

• feel a long or strong earthquake, OR
• see a sudden rise or fall in sea level, OR
• hear loud or unusual noises from the sea (like a jet plain or train), OR
• are told to evacuate by Civil Defence.

Stay out of this zone until you are told it is safe to go back.

You can expect the red zone to be evacuated several times in your lifetime.

Orange zone

The orange zone is less likely to be affected by a tsunami and includes low-lying coastal areas that are likely to be flooded in a large tsunami that inundates land.

You should leave this zone immediately if you:

• feel a long or strong earthquake, OR
• see a sudden rise or fall in sea level, OR
• hear loud or unusual noises from the sea (like a jet plain or train), OR
• are told to evacuate by Civil Defence.

Stay out of this zone until you are told it is safe to go back.

You can expect the orange zone to be evacuated maybe a few times in your lifetime

What is the difference between the red and orange zones?

You need to evacuate both zones if you feel a long or strong earthquake, without waiting for an official warning. A tsunami could be coming from close to New Zealand and there may not be time to warn everyone. If a tsunami is coming from further away there will be time for an official warning. In most cases this will mean only evacuating the red zone so that people are off the beaches and out of the water. However, if the tsunami is big, you may need to evacuate the orange zone as well.

Not in a zone?

If you are not in a tsunami evacuation zone you:

• don’t need to evacuate in a long or strong earthquake,
• don’t need to evacuate during a warning from Civil Defence,
• may wish to open your home to family or friends who need to evacuate.

An earthquake needs to be big to create a tsunami, generally more than magnitude 7.

A long earthquake shakes for more than one minute. The bigger the earthquake magnitude, the longer the shaking. If the earthquake lasts for longer than a minute, then it's a big one (whether the shaking is strong or mild).

A strong earthquake shakes so intensely that it is hard to stand up, furniture starts moving around and things fall over.

If you are near a big earthquake, the shaking will be long and strong. If you are further away, the shaking may be moderate or mild, but still long.

You will only get an official tsunami warning if there is time to issue one.

If a tsunami is created close to shore, there will not be time. This is why you must move out of the red and orange evacuation zones immediately in a long or strong earthquake - do not wait for an official warning, siren, emergency mobile alert, or for someone to tell you to go.

If a tsunami is coming from further away, an official advisory or warning will be issued, and you will be told which zones should evacuate. Advisories or warnings will be broadcast on television, radio, social media and emergency mobile alerts. Emergency services might go through evacuation zones to get people out. You can do your bit by passing information on to family, friends and neighbours.

If you are told to evacuate in an official warning you may have up to several hours to leave a tsunami evacuation zone.

Things you need to consider:

• Take valuables and important documents, as well as clothes, toiletries, medicines and supplies for children and pets. Know where these things are if you need to pack them up quickly. Depending on the impact of the tsunami you could be away from your home for days or weeks.
• Where will you go? If possible, stay with family or friends outside the evacuation zone. A Civil Defence Welfare Centre will be opened for people who need emergency accommodation.
• Secure your home as you normally would when leaving for an extended period.
• Check on your neighbours and vulnerable people you know of to see if they need help – Police and Civil Defence resources will be stretched in an evacuation.
• What is the best route for you to take? In an official evacuation, there will likely be traffic management in place, but you need to have thought about this in advance.
• Take your pets with you if you can – they are your responsibility. Civil Defence Centres generally will not accept pets, apart from service animals, so you need to have somewhere you can take your pet. Some Civil Defence Centres will have arrangements for pets nearby, so make sure you take pet food, bowls, leash, muzzle and kennel if possible.
• Residents will be allowed into evacuation zones to pick up family and pets if there is time, provided it is safe to do so before the threat becomes imminent.
• If you are farming along the coast, evacuate your whānau/family and staff first. If you have time, move livestock to higher ground.

Canterbury’s tsunami evacuation zones are based on the best information, including tsunami modelling, that we have at the time.

Our understanding of New Zealand’s tsunami risk is rapidly improving. We regularly review the tsunami evacuation zones and will change them if new modelling shows a significant change in our understanding of Waimate’s tsunami threat, or if national guidance on the way tsunami evacuation zones are developed changes.

Typically, the tsunami evacuation zones will be reviewed every 10 years.

Tsunamis can travel a surprising way up rivers – this is called a bore. Even small tsunamis can create strong currents and surges in river mouths. The tsunami evacuation zones go further inland along rivers to take this into account.

If you are not in a tsunami evacuation zone you don’t need to evacuate. Modelling has shown that in all three types of tsunami – local, regional and distant source – the potential impacts would not reach your property. We appreciate that you may still wish to evacuate, however, it is important to keep the roads clear for others who do need to evacuate from the tsunami zones.

Civil Defence won’t be able to personally help you evacuate if you need to in a tsunami. This is why it’s important to have an evacuation plan ready for you and your household. If possible, make a plan with family or friends who live outside the tsunami evacuation zones to stay with them if you need to evacuate.

For more information and resources on tsunamis visit:

Environment Canterbury’s tsunami pages https://www.ecan.govt.nz/your-region/your-environment/natural-hazards/tsunamis/

Canterbury Civil Defence Emergency Management Group’s tsunami page https://www.cdemcanterbury.govt.nz/hazards/tsunamis/