No tsunami sirens in most at-risk parts of Auckland - but they are coming

Thursday, 5 April 2018

Tsunami sirens are planned for Auckland's most at-risk areas, starting with Orewa by the end of this year.

Auckland's most at-risk coastal areas are in line for tsunami sirens, after daylight savings testing revealed … silence through most of the city.

Of the four most at-risk areas identified by GNS Science last year, Orewa, Browns Bay, Omaha and Devonport, only Omaha had a tsunami siren, which was tested on March 31.

All four areas are north of the bridge, where many Aucklanders felt tsunami sirens should be installed, according to posts on Neighbourly.co.nz.

'I believe its prudent for all low-lying areas to have an audible tsunami warning. It's a back-up alert if the digital warnings fail, if you are in the water or your cell is not to hand,' Jude Larkin of Glenfield said.

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John Watson, Albany Ward councillor at Browns Bay, which is ranked as an area which would have the second-most people affected in Auckland if a tsunami hit.

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Auckland has had tsunamis in the past, disproving the widely held belief the Gulf islands act as a barrier.

* Tsunami sirens confuse Aucklanders

Currently, 14 sites in Rodney and west Auckland have tsunami sirens.

Auckland Council was planning to install more tsunami sirens, with work being scoped out as part of its current long-term plan process, Albany ward councillor and deputy chair of the civil defence and emergency management committee John Watson said.

Exact timing was difficult to determine, as a number of decisions had to be made, such as the type of siren and power source, plus they needed resource consents, but, Watson said, with luck, installation would start at the end of year, with Orewa, the top priority.

A council officer warned sirens could be confusing and weren't the only warning system, with the council primarily relying on text messages, which could relay more precise information.

'Without effective public education and engagement activities, sirens are not generally effective in alerting the public to take action, and may cause greater confusion when activated,' Craig Glover, head of strategy and planning, Auckland Emergency Management said.

However, Watson said sirens were a well understood, effective means of alerting people to tsunami danger, although he agreed there should be a variety of warning systems.

While the national emergency mobile alerting system was not tested on March 31, Auckland Council tested its text alerts, which confused some people, according to Neighbourly posts.

The council urged Aucklanders to subscribe to its warning service at aucklandcivildefence.govt.nz.

The idea the islands in the Hauraki Gulf, including Rangitoto, Waiheke and Great Barrier would act as a barrier was disproven in the modelling done by GNS Science in its work for Auckland Council, Watson said.

'Orewa has shell deposits way back in the hills - it has happened in the past,' Watson said.

In 1868, a 2.9 metre high wave from a Chilean earthquake reached Auckland's Great Barrier Island. In 1883, the cataclysmic eruption of Indonesian volcano Mt Krakatau pushed a 1.8m high wave into Auckland, according to council records.

All 21 Auckland local boards were backing the project to install tsunami sirens, starting with most at-risk areas.

Top 10 exposed communities to tsunami

1. Orewa - 6521 people affected

2. Browns Bay - 3597

3. Omaha - 2327

4. Mt Victoria - 1969

5. Paremoremo West - 1702

6. Stanley Bay - 1668

7. Silverdale Central - 1543

8. Te Henga (Bethells Beach) - 1236

9. Stanmore Bay East - 1236

10. Edgewater - 1107

Areas with tsunami sirens

The tsunami sirens are located in Rodney at Point Wells, Whangateau, Omaha and Waiwera.

In Waitākere, sirens are located at Bethells Beach/Te Henga, Piha North, Piha South, Karekare, Whatipu, Little Huia, Huia, Te Atatu South, Harbour View Road, Te Atatu Peninsula North, Westpark Marina and Herald Island.