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Timaru District Council has revised tsunami evacuation zones due to an updated tsunami modelling that provides new insights about the likely impacts of tsunamis.
A tsunami is a series of powerful, long waves that move through the ocean caused by a sudden movement of the sea floor or by something falling into the ocean. Tsunamis are most often caused by underwater earthquakes but can also be caused by landslides and volcanic eruptions.
In the open ocean tsunamis travel fast, up to 900 km/h, but might be only a few centimetres high. As the tsunami enters shallower water the waves slow down and bunch up resulting in higher waves that are still travelling faster than you can run. The first wave that arrives is often not the largest wave – this can arrive hours later.
Local and regional source tsunamis are tsunamis generated close to New Zealand’s coast. Damaging tsunamis could be created by earthquakes on faults off the North Island or southern South Island coasts, which could reach Timaru in 1-3 hours. The 2016 Kaikoura tsunami was recorded at Timaru Port 3 hours after the earthquake but the largest wave was only 75cm from top to bottom so it didn’t do any damage.
Most tsunamis are relatively small by the time they reach the Timaru coast and don’t flood much land, if any.
But even if they don’t flood land, they can cause strong currents and surges around the coast, which can be dangerous for people in the water or at the beach or river mouths, and can affect port operations.
Environment Canterbury (Ecan) commissioned the Institute of Geological and Nuclear Sciences to complete multiple scenario tsunami modelling for the Mid and South Canterbury coastline, as part of a programme of tsunami modelling for the whole Canterbury coast.
The results show that in some parts of Timaru District the existing tsunami evacuation zones can stay the same or be reduced. However, in many places inundation from ‘worst case’ extreme tsunamis reaches further inland than the existing evacuation zones and in these areas the zones have been extended.
Timaru’s tsunami hazard is lower than other parts of New Zealand because there are no known significant tsunami sources off the South Canterbury coast and the shape of the coast tends not to amplify tsunami waves.
The new red and orange tsunami evacuation zones are similar to the existing red and orange zones. The red zone, which is the area most likely to be affected by a tsunami, includes beaches, lagoons, and river mouths. The orange zone includes low-lying coastal land, which is mostly farmland or commercial and industrial areas, with some small residential areas.
The most notable change is the creation of new yellow tsunami evacuation zones in more populated areas of the district. These areas are least likely to be affected, but could be flooded in a rare, very large tsunami. They include over 600 properties in Waipopo, Washdyke, Waimataitai, Redruth and Pareora.
Actions people should take:
- People should evacuate the red and orange tsunami evacuation zones, without waiting for an official warning, if they feel a long or strong earthquake. A long earthquake is when the shaking lasts more than a minute and a strong earthquake is when the shaking is so strong it is hard to stand up. It is possible that a tsunami has been generated off the North Island or Fiordland coast that could reach Timaru within 2-3 hours
- People do not need to evacuate the yellow tsunami evacuation zone after a long or strong earthquake, unless they are told to by Timaru Civil Defence Emergency Management or emergency services.
- For a tsunami that is coming from further away, such as the Pacific Islands or South America, people will be told which zone(s) to evacuate in an official tsunami advisory or warning. In most cases this will just be the red zone (beaches, lagoons and river mouths), but in a larger tsunami it could be the orange and yellow zones as well.
To check which zone you are now in go to the national tsunami evacuation zone map on the Get Ready Website or The Ecan Website The site has a search function that allows you to enter a property’s address to see which tsunami evacuation zone it is in.
To read the full report on the revised tsunami evacuation zones visit the Ecan Website.
What are tsunami evacuation zones?
A tsunami evacuation zone is an area you may need to evacuate from if you feel a long or strong earthquake or if there is an official tsunami warning.
Red evacuation zone - “Long or Strong, get Gone”
Includes estuaries and lagoons, river mouths, beaches and harbours. You should evacuate this zone if you experience any of the following – feel a long or strong earthquake, hear the tsunami sirens, or if you are told to evacuate in an official tsunami warning. Stay out of this zone until you’re told it is safe to go back.
You can expect the red zone to be evacuated several times in your lifetime.
Orange evacuation zone – “Long or Strong, get Gone”
Low-lying land nearest to the coastline. You should evacuate this zone if you experience any of the following – feel a long or strong earthquake, hear the tsunami sirens, or if you are told to evacuate in an official tsunami warning. Stay out of this zone until you’re told it is safe to go back.
You can expect the orange zone to be evacuated maybe a few times in your lifetime.
Yellow evacuation zone
Areas that could potentially be flooded in a very large tsunami. You do not need to leave this zone if you feel a long or strong earthquake. If you hear the tsunami sirens turn on the radio or visit the Council’s Civil Defence page. If you hear or see an announcement by Civil Defence to evacuate the yellow zone you must leave immediately. Stay out of this zone until you’re told it’s safe to go back.
While it is possible the yellow zone will be evacuated sometime in your lifetime, it is unlikely.
A tsunami evacuation zone is an area you may need to evacuate from if you feel a long or strong earthquake or if there is an official tsunami warning.
Red evacuation zone - “Long or Strong, get Gone”
Includes estuaries and lagoons, river mouths, beaches and harbours. You should evacuate this zone if you experience any of the following – feel a long or strong earthquake, hear the tsunami sirens, or if you are told to evacuate in an official tsunami warning. Stay out of this zone until you’re told it is safe to go back.
You can expect the red zone to be evacuated several times in your lifetime.
Orange evacuation zone – “Long or Strong, get Gone”
Low-lying land nearest to the coastline. You should evacuate this zone if you experience any of the following – feel a long or strong earthquake, hear the tsunami sirens, or if you are told to evacuate in an official tsunami warning. Stay out of this zone until you’re told it is safe to go back.
You can expect the orange zone to be evacuated maybe a few times in your lifetime.
Yellow evacuation zone
Areas that could potentially be flooded in a very large tsunami. You do not need to leave this zone if you feel a long or strong earthquake. If you hear the tsunami sirens turn on the radio or visit the Council’s Civil Defence page. If you hear or see an announcement by Civil Defence to evacuate the yellow zone you must leave immediately. Stay out of this zone until you’re told it’s safe to go back.
While it is possible the yellow zone will be evacuated sometime in your lifetime, it is unlikely.
Where do I evacuate to?
If you need to evacuate a tsunami evacuation zone move well inland, so you are out of all evacuation zones, or to higher ground. We suggest you go to friends or family outside of the evacuation zones if you are able to. Timaru District Council may open Civil Defence Centres during an evacuation, but this may take some time.
If you need to evacuate a tsunami evacuation zone move well inland, so you are out of all evacuation zones, or to higher ground. We suggest you go to friends or family outside of the evacuation zones if you are able to. Timaru District Council may open Civil Defence Centres during an evacuation, but this may take some time.
I’ve felt a long and strong earthquake, should I evacuate?
If you are in the red or orange zone and you feel a long or strong earthquake don’t wait for an official warning - self-evacuate immediately well inland or to higher ground, out of the evacuation zones. There may not be time for an official warning to be issued.
If you are in the red or orange zone and you feel a long or strong earthquake don’t wait for an official warning - self-evacuate immediately well inland or to higher ground, out of the evacuation zones. There may not be time for an official warning to be issued.
The tsunami sirens are going off, does this mean I need to evacuate?
If you are in the orange or red zone and hear the tsunami sirens you must evacuate those zones immediately and move well inland out the evacuation zones. If you’re in the yellow zone and hear the sirens, check to see if there is a Civil Defence tsunami evacuation warning in place for the yellow zone.
If you are in the orange or red zone and hear the tsunami sirens you must evacuate those zones immediately and move well inland out the evacuation zones. If you’re in the yellow zone and hear the sirens, check to see if there is a Civil Defence tsunami evacuation warning in place for the yellow zone.
Will Civil Defence help me to evacuate in a tsunami?
Civil Defence won’t be able to personally help you evacuate if you need to during a tsunami evacuation. 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.
Civil Defence won’t be able to personally help you evacuate if you need to during a tsunami evacuation. 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.
I’m not in a tsunami evacuation zone but can I evacuate if there’s a tsunami and I’m scared?
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.
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.
My property is in a tsunami evacuation zone – what will this mean for my insurance?
The tsunami risk to Timaru hasn’t changed as a result of the new modelling. There is no increased probability of a tsunami happening with the new science. The new modelling just shows that the inundation area comes further inland than previously known. It’s important to note that this modelling is based on conservative worst-case scenarios.
The tsunami risk to Timaru hasn’t changed as a result of the new modelling. There is no increased probability of a tsunami happening with the new science. The new modelling just shows that the inundation area comes further inland than previously known. It’s important to note that this modelling is based on conservative worst-case scenarios.
How else can I get prepared for a tsunami?
If you live or work in a tsunami evacuation zone you should have an evacuation plan. This includes where and how you will evacuate. There’s lots of helpful evacuation tips on our website www.timaru.govt.nz
If you live or work in a tsunami evacuation zone you should have an evacuation plan. This includes where and how you will evacuate. There’s lots of helpful evacuation tips on our website www.timaru.govt.nz
Will the tsunami zone be shown on my LIM?
LIMs will be updated in the future with the new evacuation zones. This will only be recorded as an educational/ informational piece as tsunami evacuation zones aren’t used for land use planning or development considerations.
LIMs will be updated in the future with the new evacuation zones. This will only be recorded as an educational/ informational piece as tsunami evacuation zones aren’t used for land use planning or development considerations.
Last updated: 07 Nov 2022