NZ 'at risk from tsunamis'

A coastal property boom and lax development rules are putting New Zealanders' lives at risk from tsunamis, an expert says.

Hamilton-based hydraulic engineer Alastair Barnett, who is due to speak in Whangarei tonight, says people have ignored the danger posed by tsunamis, despite the Boxing Day event that claimed almost 250,000 lives around the Indian Ocean.

A major tsunami hitting Northland was a one-in-500-years event, which meant people on the coast had a roughly 15 per cent chance of encountering a giant wave in their lifetime.

That was about the same chance as being involved in a serious car accident, Dr Barnett said.

Yet tsunami protection was all but neglected in New Zealand.

"It's still seen as a problem only where the last big one happened. Councils ought to be looking at their coastlines and taking sensible precautions," he said.

Councils enforced protection against river flooding, requiring stopbanks to withstand one-in-500-years floods, and buildings were designed to stay standing after a one-in-500-years earthquake -- but tsunamis were treated differently.

"It seems a bit inconsistent to ignore them. Why are tsunamis so different?"

Dr Barnett said coastal land should face the same kind of planning restrictions as flood-prone river plains and development needed tighter controls.

Houses built along the coast -- some of which were "practically on the high tide mark" -- should be set back, or raised on timber piles or structural concrete walls.

Such houses would still be damaged in a tsunami, but the people inside would be protected.

Whangarei was "absolutely" at risk, as harbours could amplify a tsunami, he said. Extra protection for the city and oil refinery was needed.

Dr Barnett said he had been involved in the development of Northport, which was designed with tsunamis in mind.

Northland's most recent tsunami was a three-metre wave that hit Tutukaka in 1960, generated by a magnitude 9.6 earthquake off the coast of Chile. That tsunami hit at low tide, and few people lived around Tutukaka then.

- NORTHERN ADVOCATE (WHANGAREI)