When there is an earthquake in the open ocean, shockwaves caused by the earthquake can produce series of fast-moving waves or surges, known as tsunamis, that can move at speeds of between speeds of 600–700 km/hr towards land.
When these tsunami waves hit the shallower areas near the coast they can behave like storm surges, suddenly increasing in height and speed.
Depending on their speed and amount of water they are carrying, tsunamis can cause significant damage and loss of life by quickly pushing debris such as trees, building materials, vehicles, and boats further inshore.
It's important to know which parts of Porirua are most likely to be affected by a tsunami, so check out our map below
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.
It's vital that you know the tsunami evacuation routes from where you live, work and play.
Visit the New Zealand ShakeOut 2019 website to find out all you need to know about this year's Tsunami Hikoi on 17 October.
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)
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
If you are near the coast and in a tsunami zone
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.
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.
The radio station frequencies for Wellington/Hutt Valley, Porirua are:
You can also sign up to receive emergency alerts to your iOS and Android devices through the Red Cross Hazards App.
Council staff marked the Kaikoura earthquake's second anniversary with a tsunami walk out drill14 Nov 2018