Tsunami Evacuation Zones
This page explains Porirua's tsunami risk, what the warning signals are, and gives links to maps in Google and printable pdfs showing the tsunami evacuation zones for Porirua City.
What is Porirua's tsunami risk?
Fortunately for Porirua, we face one of the lowest risks in the region of a distantly generated tsunami, such as the one from the Chilean quake on 28 February 2010, or the Japan quake on Friday 11 March 2011, which resulted in wave heights of about 1.5m hitting North Cape several hours later. Mana Marina recorded surges up to 30cm high after the Japanese quake. However, we are still very much at risk from tsunami created by a local source, such as the fault lines off our coast. There are signs of a 15m high tsunami dating from the 14th or 15th Century along Porirua's western coast.
Tsunami produce a series of very low, but extremely fast-moving long waves or surges. They can have periods of over an hour 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 the warning signal?
We receive tsunami 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 warning are broadcast on public radio, and usually on the TV as well.
In the event that Porirua has to evacuate people due to a tsunami, we will alert the people who need to evacuate with sirens. These may be from Police or Fire Service vehicles moving through the affected areas, or the fire station sirens at Titahi Bay and Plimmerton. The fire station sirens will sound continuously (if they stop after a couple of wails then they are just summoning the local volunteers for a fire, or testing the siren). Some council vehicles may also have mounted PA systems playing the "Sting" siren, followed by a warning message.
Those organisations who are signed up for Readynet will receive a message by email and text.
Tsunami evacuation maps
Click the map to go to the Porirua Tsunami Evacuation Zones map in Google.
For a general overview of tsunami evacutaion zones in the Wellington region, read our brochure - It's Easy - Know your tsunami zone (727KB pdf)
Printable maps for Porirua
The map below has been developed by GNS Science and Greater Wellington Regional Council, with input from Emergency Management staff. For more information on how these maps were created read Metadata for PCC tsunami evacuation zones (36kb pdf)
For a more detailed view of your area, view the Index map first to find which map you should be looking at.
Tsunami Evacuation Zone Map Index (305kb pdf)
Tsunami - Map 1 - Kenepuru (462kb pdf)
Tsunami - Map 2 - Porirua CBD (402kb pdf)
Tsunami - Map 3 - Takapuwahia (284kb pdf)
Tsunami - Map 4 - Okowhai Lagoon (277kb pdf)
Tsunami - Map 5 - Titahi Bay South (677kb pdf)
Tsunami - Map 6 - Paremata/Papakowhai (464kb pdf)
Tsunami - Map 7 - Titahi Bay North (506kb pdf)
Tsunami - Map 8 - Mana Bridge (318kb pdf)
Tsunami - Map 9 - Golden Gate (295kb pdf)
Tsunami - Map 10 - Whitby (511kb pdf)
Tsunami - Map 11 - Whitby/Pauatahanui (321kb pdf)
Tsunami - Map 12 - Pauatahanui Inlet (134kb pdf)
Tsunami - Map 13 - Pauatahanui (86kb pdf)
Tsunami - Map 14 - Motukaraka Point (117kb pdf)
Tsunami - Map 15 - Grays Road (71kb pdf)
Tsunami - Map 16 - Mana (381kb pdf)
Tsunami - Map 17 - Plimmerton Domain (390kb pdf)
Tsunami - Map 18 - Plimmerton (238kb pdf)
Tsunami - Map 19 - Ulric St (116kb pdf)
Tsunami - Map 20 - Hongoeka Bay (277kb pdf)
Tsunami - Map 21 - Pukerua Bay (235kb pdf)
What do the colours mean?
Tsunami come in different sizes, and we don't want to evacuate people who are actually not in danger, so we have a series of evacuation zones that we can use, based on the size of the tsunami that may be going to affect us.
If we receive warning of a tsunami, you will be told which zones to evacuate. For example, if we say to evacuate the Red and Orange Evacuation Zones, then people in those zones should leave, but people in the Yellow Evacuation Zone do not need go.
You should immediately evacuate ALL of the zones if there is a large local earthquake where it is hard to stand up, or a rolling earthquake that lasts for more than a minute, or if you see or hear the ocean behaving strangely. A tsunami may be only minutes away, and we will not have time to give you a warning.
Red evacuation zone
Even small tsunami can have dangerous effects on tidal currents within Porirua Harbour and along the coast, making swimming and boating dangerous. Due to unpredictable surges, people will be asked to stay off all beaches, as well as out of the water. Our Red Evacuation Zone includes the harbour, as it's so shallow.
Orange Evacuation Zone
If we have warning of a larger tsunami, we may need to evacuate homes or businesses which are close to the shore.
For the largest tsunami, we may need to evacuate homes and businesses in the Yellow Evacuation Zone as well, but a tsunami of this size is extremely rare.
You should immediately evacuate ALL of the zones if there is a large local earthquake
View a list of our Civil Defence Centres.
Check our Local Emergencies page for the current status of any emergency.