Your best warnings for a tsunami are:
- a long rolling-motion earthquake that’s longer than a minute,
- a strong earthquake that makes it hard to stand up, or
- unusual ocean behaviour: loud or strange noises coming from the sea (e.g. like a jet plane or train) or sudden sea level changes.
If an earthquake is long or strong, you need to be gone.
It is unlikely that a tsunami has been created, but it is better to be safe than sorry. If a tsunami is coming from close to our shore, there will not be any time to issue an official warning, sound sirens or to send an emergency mobile alert. The earthquake is your best warning.
An official tsunami warning can be issued for a tsunami where time permits CDEM personnel to do so, especially for a tsunami coming from outside the Canterbury region or across the Pacific Ocean. You will hear Civil Defence official tsunami warnings on the radio, on television, on social media, or via an Emergency Mobile Alert, telling you which zones to evacuate.
Sirens and when to return home
Sirens installed along the Christchurch coastline are intended to warn you about a tsunami generated in the Pacific Islands or across the Pacific Ocean, and if there is time, for a tsunami generated further afield from Canterbury i.e. in the North Island's east coast.
Sirens are not intended to warn you about a tsunami created close to our shore. A long or strong earthquake will be your only warning of a tsunami created close to our shore.
Safe to return, 'all clear' messages will be broadcasted by Civil Defence using radio, TV, radio, Council's Newsline(external link), and social media.
You can also do your bit by sharing official warnings with friends and family in the evacuation zones.
Emergency Mobile Alerts
Emergency Mobile Alerts are messages broadcasted by authorised agencies to keep people safe. The alerts can be targeted to areas affected by serious hazards, including tsunami. If your phone is on, capable and inside the targeted location, you should get the alerts.
Emergency Mobile Alerts will only be used for serious hazards that involve threats to life, health or property, or in some cases for test purposes. If your phone is on, capable and inside the targeted location, you should get the alerts. You don’t have to download an app or subscribe to a service, just ensure your phone is capable and updated.