Tsunami warning sirens for Tauranga

Tauranga's low lying suburbs will soon be dotted with air-raid-style tsunami warning sirens, sparked by Japan's deadly earthquake and tsunami this year.

Tauranga City Council yesterday pledged $400,000 to kick-start the job of establishing a network of sirens along the coast and the city's harbour margins to warn the 51,000 at-risk city residents, the Bay of Plenty Times reported.

An investigation by council planning engineer Barry Somers put the cost of sirens at between $760,000 and $1.4 million.

He recommended sirens mounted on 10-metre poles for the harbour margins and sirens on power poles for coastal suburbs.

Mr Somers said a challenge for the most expensive $1.4 million "mega sirens" would be to find locations along the coast where they would not deafen residents.

They are so loud they have to be 100m from a house - or with 200m of clear space in both directions.

In the United States ultra-loud sirens warning Midwest's "tornado alley" residents, are loud enough to wake people 1.8km away.

No sirens of their kind have been used in New Zealand, and each costs $130,000, the New Zealand Herald reported.

Bay of Plenty's civil defence emergency management group had ranked lowly in systems that could be used to warn residents of impending disaster.

But Japan's tsunami prompted the council to make its own investigation.

"The original report we received did not include sirens as a warning option and, clearly, this one puts a whole new perspective on it," Tauranga Mayor Stuart Crosby told the New Zealand Herald.

"There's no one national warning system, particularly for our coastline, and that seems a bit ridiculous.

"The practical reality is that we may never need them, but also we may need them tomorrow - such is the nature of nature."

There are already tsunami warning sirens in Northland, Rodney, Waitakere and Hawke's Bay.

Civil Defence public information manager Vince Cholewa told NZPA there was a national warning system but getting warnings to coastal streets and buildings meant councils were looking at what they could do.

Civil Defence supported the installation of warning sirens but it was important for councils to do what worked best for their areas.

"There is no one perfect system. The key is to get the warning out in a range of different ways because that's the only way you are actually going to reach a good number of people. And it's really important that people spread it."