Tsunami safety

Tsunami is a Japanese word meaning 'harbour wave'. Tsunami are large and powerful ocean waves that can grow in size as they reach the shore. These waves can move very quickly and for very long distances. Some tsunami have been known to travel for thousands of kilometres across the ocean and travel at speeds of up to 800 km per hour. 

The most common cause is a sea floor earthquake. Other triggers are under sea landslides, under sea volcanic eruptions, and meteorite impact. Sudden changes to the sea floor cause the ocean to flow away from the disturbance, creating waves. 

To find out more about tsunami see GNS Science - www.gns.cri.nz/Home/Our-Science/Natural-Hazards-and-Risks/Tsunami  

There are three ‘zones’ in the Wellington region; red, orange and yellow. The yellow (outer) zone has been defined by scientific modelling of the maximum possible tsunami run up height (the worse-case scenario for our region) from earthquakes on the subduction zone to the east of the North Island.

• If you feel a LONG or STRONG earthquake, evacuate all of the tsunami zones (red, orange and yellow) as soon as the shaking stops. 
• If there is an official warning, then only evacuate from the zones stated in the warning - either red or orange zones.
• If you are not in a tsunami zone, then you don't need to evacuate. Some areas may be cut off if your normal access goes through a tsunami evacuation zone, so be prepared to stay at home for some time until the all-clear is given. 

The Red Zone is the beach and marine environment, and some very low-lying areas. This zone is the one we ask people to stay out of most often as a result of smaller tsunamis.  

The Orange Zone (including the red zone) is the area we may evacuate for a large earthquake in the Pacific, such as near South America, causing a tsunami wave of up to 5 metres at the Wellington coastline. Alerts and evacuation advice would be issued by Civil Defence and distributed to the public for this type of tsunami because we have more time. 

The Yellow Zone (including the orange and red zones) is the area that you must evacuate from if you feel a long or strong earthquake. This zone has been defined by scientific modelling of the maximum possible tsunami run up heights (the worse-case scenario for our region) from earthquakes on the subduction zone to the east of the North Island. In the case of a long or strong earthquake, everyone who is in the yellow zone (and orange and red), needs to evacuate immediately after the shaking stops.

The Blue Lines mark the edge of the yellow zone in parts of our region. 

There is an online map above on this page where you can search your address. You can also view pdf maps and print and keep it as part of your emergency plan. 

Tsunami Zone Maps

We recommend knowing where your zones are for home, work, schools, sports grounds or other places where you may regularly be within the tsunami zone. 

Many areas across the Wellington region have a blue line painted across roads and footpaths. The blue lines show the safe places to evacuate to if there is a long or strong earthquake. That is, an earthquake that lasts longer than a minute or one that is too strong to easily stand-up in.  

The blue lines show the maximum possible run-up heights (worst case scenario) and are based on scientific modelling by GNS Science and Greater Wellington Regional Council.

The Tsunami Blue Lines are not in all parts of the region.

1. If you feel an earthquake that is either Long (longer than a minute) OR Strong (enough that it’s hard to stand up), evacuate immediately after the shaking stops. Do not wait for an official warning. The earthquake is your warning that there could be a tsunami. Get to the nearest high ground, or as far inland as possible.
2. If a national warning has been issued and you are told to by authorities.

3. This evacuation advice overrides any COVID-19 Alert Level 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.

Long means an earthquake that lasts for more than one minute. Strong means an earthquake that is hard to stand up in. An earthquake does not have to be both to produce a tsunami, it could be either.

If you feel a LONG or STRONG earthquake: Drop, Cover and Hold during the shaking. 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. This evacuation advice overrides any COVID-19 Alert Level 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.

And: If you are told to evacuate by officials, follow the evacuation advice. Evacuation advice overrides any COVID-19 Alert Level requirements to stay at home. Move immediately. 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.

After a long or strong earthquake a tsunami may reach Wellington in as little as 10 minutes. When the shaking stops, and if you live or work in a tsunami zone, you will have to make a quick decision on whether to stay or go.  We recommend evacuating out of all tsunami zones (red, orange and yellow) rather than staying in your building. There are currently no building standards for tsunami in New Zealand, so it cannot be determined if a building is tsunami safe and can be used for vertical evacuation. You should only consider vertical evacuation if there is no other option. If you do decide to stay, you need to be on the fifth floor or higher. You will need to be prepared to stay for up to 7 days without official support.

There are several factors to consider, and this is something you and your household or workplace will need to discuss and decide.

Whatever you decide works for you, we strongly recommend you spend some time putting together a grab bag and practising the route you would take if you do leave the building.

For further information see WREMO’s statement about Vertical Evacuation: here

A long or strong earthquake is the natural warning for a tsunami - If you feel an earthquake that is either Longer than one minute OR Strong enough to make it hard to stand up, then get to the nearest high ground, or as far inland as possible, out of all tsunami zones, as soon as the shaking stops. Do not wait for an official warning. The earthquake is your natural warning.

= Long OR Strong, Get Gone! 

If an earthquake occurs in the Pacific Islands or further away, we may not feel the earthquake. In this case, because the earthquake has occurred farther away and there is no damage to our infrastructure, there is the possibility for official warnings. If there is a tsunami threat to New Zealand, a national warning will be issued and WREMO will provide alerts and information on areas, if any, that need to be evacuated. This will be done through a range of channels like radio, T.V broadcasts, social media (WREMO Facebook and Twitter), WREMO and local council websites, and Emergency Mobile Alerts.

If you FEEL an earthquake that is either longer than a minute OR strong enough that it’s hard to stand up, this could be big enough to cause a tsunami that reaches Wellington region shores within 10 minutes.

In a big earthquake like this it is likely that communications and infrastructure will be damaged and will not work. People need to know that a long or strong earthquake is your natural warning that there could be a tsunami generated and evacuate immediately without being told.

If an earthquake occurs in the Pacific Islands or further away, and we do not feel the earthquake, communications will be working and there is more time before it’s arrival (1-3 hours in the Pacific islands and up to 12 hours from South America) to issue warnings. There are many ways we have to warn people in this case for example, radio and T.V broadcasting, Social Media and Emergency Mobile Alerts.

Walk, run or cycle, if you can. Vehicles should only be used by emergency services and those with mobility impairments, including wheelchair users.  

Evacuate tsunami zones by foot or bicycle, don't drive - this is because roads may be blocked by debris or traffic jam. For those who can't walk or cycle, trying to drive out is their only option, and you could be preventing them from evacuating safely. For example, people with mobility impairments.  

If you need help evacuating or know someone that does, have a conversation with your neighbours about how everyone can get out safely. 

A local-source tsunami is one that has been generated by an earthquake near New Zealand. In this case, we feel the earthquake. If this earthquake is either long or strong, it is our natural warning that a tsunami could have been generated and you must evacuate immediately after the shaking stops if you are in a tsunami zone. This type of tsunami could arrive in as little as 10 minutes so you need to evacuate immediately after the shaking stops.

A distant-source tsunami is one that has been generated from an earthquake that has occurred away from New Zealand like the Pacific Islands, or off the coast of South America.

If the earthquake occurs near the Pacific Islands, the travel time to New Zealand is between 1-3 hours.

If the earthquake occurs off the coast of South America, the travel time to New Zealand is up to 12 hours.

Evacuate to the nearest high ground or as far inland as possible outside the zones, past the tsunami blue lines if you have them. 

Identify your quickest route to get outside the zone by looking at the tsunami zone maps and practise your evacuation so you know where to go.

See the tsunami zone maps on this website above

The reason we don't use tsunami sirens in the Wellington region is in keeping with international best practice - that tsunami sirens are inappropriate as a warning system in regions subject to local sourced tsunami. The National Emergency Management Agency (NEMA), GNS Science and New Zealand’s Tsunami Working Group all agree with this international best practice.   

This is because:

• The time it takes for scientists to determine whether an earthquake has created a tsunami threat and then send out official warnings can be longer than the time it takes for a local source tsunami to reach the coast. A tsunami could arrive in as little as 10 minutes. 
• International research (especially from Japan) shows that the existence of sirens creates a false sense of comfort with the public in that they expect to be warned by the siren, rather than making a decision to respond to the earthquake itself.
• The earthquake damage itself can make the sirens fail (in the 2011 Japanese earthquake and tsunami, 17 out of 27 sirens failed from power cuts or earthquake damage).
• Sirens have led to people ignoring them or delaying evacuation due to false alarms.
• There are problems with the effectiveness of the sirens through audibility (especially with Wellington’s wind).

So, the best and most reliable warning system for local source tsunami in New Zealand is the natural warning itself.

In a distant source tsunami we have more time (between 1-12 hours) to warn people through other means such as radio and T.V broadcasts, Emergency Mobile Alerts (phone messages) and social media. Therefore sirens are not required for these events.

For further information see WREMO’s position on sirens at www.wremo/sirens 

Often the sirens you may hear every now and then is the Volunteer Fire Stations to alert volunteers that there is a fire to respond to.

Lower Hutt has flood sirens which were installed in the 1970’s for flood warnings, not tsunamis. The sirens are in flood areas not in tsunami risk areas – for example there are sirens in Manor Park and Wainuiomata, which are not in any tsunami evacuation zone. These won't be used for tsunami in the future.

Listen to the news and radio and follow WREMO on Facebook and Twitter. Updates will also go on the WREMO and local council websites.

WREMO Facebook: @WREMOnz

WREMO Twitter: @WREMOinfo

WREMO Website: wremo.nz

Emergency Mobile Alerts are messages about emergencies sent by authorised emergency agencies to capable mobile phones. The alerts are designed to keep people safe and are broadcast to all capable phones from targeted cell towers.

The alerts can be targeted to areas affected by serious hazards and will only be sent when there is a serious threat to life, health or property, and, in some cases, for test purposes.

To find out more see here: Emergency Mobile Alert — Get Ready — Emergency preparedness in New Zealand

The Get Ready website has a list of phones capable of receiving Emergency Mobile Alert. If your phone is on the list, ensure the phone is updated to the latest available operating system.

Find out more here: Emergency Mobile Alert — Get Ready — Emergency preparedness in New Zealand