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Image for the Tsunamis page.
This page contains information on what to do in the event of a tsunami alert.
Updated: 1/09/2020 1:09 p.m.
Photograph of a tsunami wave.
​Tsunami wave

What is a tsunami?

A tsunami is a series of sea waves generated by underwater earthquakes or large landslides.

Natural warning signs of a tsunami 

  • Feel a strong earthquake and the ground shaking,
  • Weak rolling earthquake lasting a minute or more,
  • Unusual sea behaviour, such as a sudden sea level fall or rise,
  • The sea making loud and unusual noises, especially roaring like a jet engine.

Tsunami warnings

Tsunami warnings are issued by the Ministry of Civil Defence and Emergency Management who send details of the threat through to local Civil Defence personnel.

Based on the information received from the Ministry the local controller makes a decision whether or not to sound the tsunami sirens.

Tsunami sirens 

Tsunami sirens and their strobe lights are just one part of a range of formal and informal warning systems, any one of which can alert people to a tsunami.

The sirens and lights are a strong signal to seek further information.

When there is a tsunami warning the siren will sound intermittently.  The strobe light will flash throughout the event, from beginning to end.

If you hear a siren, seek further information. 

Turn on a radio, television or computer and search for information on Council websites, social media sites, or the Civil Defence Northland Facebook page.  If you don't have access to any of these, contact someone you think may have. 

Tsunami sirens don’t necessarily mean you need to evacuate the area right away or even at all. They do mean you need to find out what the level of threat is.

Follow the instructions given by Civil Defence and spread the word to people you think may be at risk.

Civil Defence Northland on Facebook

Coastal Community Response Plans

Community Response Plans have been prepared for areas in the district to identify hazards in those areas which may impact on the community.

The tsunami sirens fit in with our Coastal Community Response Plans, which include community telephone trees, maps that show the areas likely to be flooded (depending on the size of the tsunami), evacuation routes and safe zones.

If you want to find out more about your local community response plan:

  • call Northland Regional Council on +64 9 438 4639
  • call Whangarei District Council on +64 9 430 4200
  • visit the Northland Regional Council website.

Northland Regional Council

Siren sounds, tsunami inundation maps and further information on tsunami can be found on the Northland Regional Council website by following the link below.

Northland Regional Council - Tsunami Information

For more information on Coastal Community Response Plans visit the page below.

Getting information in an emergency

We encourage you to get information every way you can in an emergency. Our geography and lifestyles mean that no single system works for everyone.

  • Turn on a radio, television or computer; or

  • contact a friend, relative or neighbour for more information.

Civil Defence text message alerts

The Northland Civil Defence Group offer free text message alerts about impending flood, tsunami or other civil defence emergencies.

Follow the link below for instructions on how to register.

Sign-Up for Civil Defence Text Message Alerts 

When a tsunami threatens

  • Do turn on your radio and follow all instructions
  • Do take your Getaway Kit with you if you are told to evacuate
  • Do leave the area immediately if you are on the beach or near a river when a strong earthquake occurs
  • Do go at least 1 kilometre inland or 35 metres above sea level
  • Don't go to a river or beach to watch the waves come in.

Tsunami siren testing

The tsunami siren network is tested bi-annually at the beginning and end of Daylight Savings on the Sunday morning at 09.20am.

The siren network is tested by Northland Civil Defence, Northpower and Top Energy. Any maintenance issues are reported and corrected to keep the system in good working order.


Whangarei District Council owns this website and the information, images and photographs in it are subject to copyright. No portion may be copied or republished without prior permission of Whangarei District Council. We have made every reasonable effort to provide accurate and reliable information. The use of any information is at the website visitor’s own risk and discretion.