Tsunamis

If it's long or strong, get gone!

What is a tsunami?

A tsunami produces a series of very low, but extremely fast-moving long waves or surges. They can be an hour our more apart and move at speeds of 600–700 km/hr in the open ocean. At the coast they slow down and steepen up to sometimes produce breaking waves. More commonly though, they cause a very rapid onshore flow of water, like going from low tide to high tide, to a higher tide in minutes. In doing so, they can cause widespread coastal inundation. Much of the damage comes from debris being pushed along in the flow – trees, building materials, vehicles, and boats. 

What is Porirua's tsunami risk?

All of New Zealand is at risk of earthquakes and all of our coastline is at risk of tsunamis. We can’t predict when earthquakes and tsunamis will happen, but you can help protect yourself and your family by knowing if your property is in a tsunami evacuation zone and what you need to do.

In an earthquake

  • Drop, cover, hold – this makes you a smaller target, stops you being knocked over and protects your head, neck and vital organs.

If you are near the coast and in a tsunami zone

  • If it’s long or strong be gone – if you feel an earthquake that rolls for more than a minute OR makes it hard to stand up, don’t wait for a tsunami warning as there may not be time for one in your area. Move to high ground or as far inland as you can. Walk if you can. Stay there until you get the all clear.
  • Know where to go, find out who can help you and who might need your help.There are no tsunami blue lines in Porirua – take the time now to find out where you need to evacuate to.

World Tsunami Day

World Tsunami Awareness Day on 5 November is a chance for all of us to find out more about tsunami and how to prepare for them as all of New Zealand's coastline is at risk of tsunami.

World Tsunami Awareness Day is a chance for all New Zealanders to learn more about the tsunami risk in our regions, know how to prepare for them and update our plans to keep our families safe.

You can find out more on the United Nations website.

Tsunami evacuation zones

Porirua Tsunami Evacuation Zones interactive map

Porirua Tsunami Evacuation Zones

City overview: A4 map (1MB pdf), A3 map (3MB pdf)

Golden Gate (295KB pdf)

Grays Road (71KB pdf)

Hongoeka Bay (277KB pdf)

Kenepuru (462KB pdf)

Mana (381KB pdf)

Mana Bridge (318KB pdf)

Motukaraka Point (117KB pdf)

Okowhai Lagoon (277KB pdf)

Paremata/Papakōwhai (464KB pdf)

Pāuatahanui (86Kb pdf)

Pāuatahanui Inlet (134KB pdf)

Plimmerton (238KB pdf)

Plimmerton Domain (390KB pdf)

Porirua CBD (402KB pdf)

Pukerua Bay (235KB pdf)

Takapūwāhia (284KB pdf)

Titahi Bay North (506KB pdf)

Titahi Bay South (677KB pdf)

Ulric Street (116KB pdf)

Whitby (511KB pdf)

Whitby/Pāuatahanui (321KB pdf)

What do the colours mean?

The red zone is the beach and marine environment, and some very low lying areas. This area is the one we ask people to stay out of most often as a result of smaller tsunamis. Evacuate this area when instructed to, or immediately after any long or strong earthquake.

The orange 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.

The yellow zone is the self-evacuation zone which means if you feel a long or strong earthquake, then get yourself out of all zones. This zone has been defined by modelling of earthquakes on the subduction zone to the east of the North Island, the worst case scenario for the Wellington region.

Tsunami warnings

What is the warning signal?

The earthquake might be your only warning. If you are in a coastal area and experience a long OR strong earthquake, it's hard to stand up, or you observe strange sea behaviour such as the sea level suddenly rising or falling, or hear the sea making loud and unusual noises or roaring like a jet engine, do not wait for an official warning.  Take immediate action when the shaking stops and self-evacuate to the nearest high ground.  Listen to your local radio station for more information.

For a distant sourced tsunami, we receive warnings through the National Warning System, which is the official warning system for New Zealand. It uses information from the Pacific Tsunami Warning Centre. Once received, these warnings are broadcast on public radio, and usually on television.  Check the Ministry of Civil Defence and Emergency Management website to see if your phone is capable of receiving Emergency Mobile Alerts.

Will there be a tsunami siren?

No, Porirua does not have tsunami sirens. The Titahi Bay and Plimmerton fire sirens are not used for a civil defence emergency. Some Council vehicles have mounted PA systems playing a warning message. These vehicles may circulate some key areas of the city as necessary.

If you hear anything unusual such as messages over a loudspeaker, tune into a local radio station, or check our homepage to see if there is anything you need to know about.

What are the local radio station frequencies?

The radio station frequencies for Wellington/Hutt Valley, Porirua are:

  • National Radio (Radio NZ) 567 AM, 101.3 FM, 101.7FM, 104.5 FM
  • Newstalk ZB 1035 AM
  • Classic Hits 90 FM
  • More FM 94.7 FM, 100 FM
  • The Breeze 94 FM, 98 FM
  • Radio Live 98.7 FM, 1233 AM

You can also sign up to receive emergency alerts to your iOS and Android devices through the Red Cross Hazards App.

Tsunami evacuation plans

Plan now 

  • Find our which evacuation zone you are in and make a plan with your family about what to do after an earthquake. You need to do this for your home, school, work place, or anywhere you frequent that might be in the tsunami zone.
  • Know where to go, find out who can help you and who might need your help.
  • Have a grab bag handy with essential items, so you can leave without delay. Remember, you might not get back into your house, so consider a USB stick or similar with scans of important documents, photos etc.
  • Evacuate on foot and go to friends or family outside the evacuation zones (roads can get jammed with traffic easily). 
  • Do not pass through an evacuation zone to get home or collect your children from school or childcare – they will have their own evacuation systems if needed.
  • During an emergency, local police, fire, and emergency services officials are trying to save your life. Give them your fullest cooperation.
  • Never go down to the beach to watch for a tsunami. The wave moves much faster than you can run.

Latest news

News - Walkout logo

Head for the hills

To mark the anniversary of the Kaikoura earthquake Porirua City Council staff will walk off the job to practice a tsunami evacuation.

2 Nov 2017

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