A scientist's simulation of a tsunami hitting the east coast of the Coromandel Peninsula suggests the waves could be higher than 10 metres.
Jose Borrero sits on the government's tsunami expert panel and is part of a team of scientists in Raglan researching the effects of a worse-case earthquake in the Kermadec Trench, using computer modelling.
Mr Borrero said a serious earthquake in the area could result in tsunami waves hitting the Coromandel in under an hour.
"Inundation heights of up to 10 or 12 metres in places and the type of damage we would expect would be on par with what was seen in Japan in 2011, so very extreme damage is possible from this type of tsunami source."
He said it wasn't fanciful thinking.
"This kind of earthquake has happened before and could very well happen here.
"The waves from such an earthquake would reach the Coromandel coast in less than an hour and produce substantial inundation and potential devastation throughout the region."
Mr Borrero said there was no other technology here which was similiar to the computer modelling he was using.
He would like to see it taken up by the government to help Civil Defence and councils assess the potential effect of tsunami waves.
"What we have is something that can basically tell us not only the tsunami height, but how fast the water is going to flow, what part of the port is going to experience the strongest currents, when that is going to happen and how long those currents will last."
He said the system used existing international and local sensors in the ocean and would not be expensive to put into operation, because it would only take one person to teach local councils and Civil Defence how to use it.
Officials: Plan doesn't cover 10m waves
Coromandel officials said they were preparing for the possibility of a future tsunami generating waves of up to 2.5m but not for those about 10m.
Coromandel District Council Deputy Mayor Peter French said it would have to move communities into the hills to prepare for such an event, which was not practical.
"Up to 10m - that's just way outside the scenarios we anticipate through our Thames Valley Civil Defence local plans.
"We're talking about 2.5m locally generated waves along that east coast, that's the sort of levels that our plan addresses."
Mr French said, with every risk, there was always a worst case scenario.
"But how do you actually plan and mitigate that risk? It would be a huge undertaking.
"Look at the Christchurch earthquake - how could you possibly plan and mitigate for the devastation that was experienced in Christchurch, and this would be sort of at that level, wouldn't it," he said.