Most tsunami sirens in Auckland to be deactivated due to theft, age

Most of Auckland's tsunami warning sirens will be deactivated from December.

Across the Rodney, Albany and Waitākere wards 42 sirens will be decommissioned from 1 December and replaced by alerts sent to mobile phones.

Auckland Emergency Management head of response and recovery John Cranfield told Morning Report they were not commonly used:

He said for those who did not have a cellphone, warnings would be distributed on social media and the radio.

"In Auckland, we've just got about 14 coastal communities that have got sirens at the moment."

Sirens were not placed across the region and that was replicated across the country, he said.

"They're not a commonly used tool across the country," so the decision was made to deactivate them, Cranfield said.

"The reason for doing that is it's an older network, they were installed in approximately 2008 and they're reaching the end of their lives.

"They've also been prone to significant amount of theft and vandalism, which is really unfortunate and ultimately this has meant that the system is not one where we're comfortable relying on particularly when we have other really good tools available to us."

Also, people needed to understand the natural warnings of a tsunami, he said.

Cranfield said for anyone near the shore who experiences "a long earthquake, a rolling earthquake that lasts a minute or more, or if it's a strong earthquake, that makes it hard to stand up, or if you notice a sudden change in the sea level, or loud and unusual noises from the ocean, then it's important to evacuate inland or to higher ground immediately. Remember, if it's long and strong, get gone".