Northland tsunami siren replacement project construction manager Tawanda Shiri with siren 21 that's taking shape at Whangārei's Port Nikau. Photo / Susan Botting
New Zealand’s biggest tsunami siren network upgrade is rolling out across Northland this year.
The $6.7 million to date four-year project funded by Northland ratepayers is the country’s first major region-wide project using new Danish-designed solar-powered tsunami siren units. The 94-siren rollout is expected to be completed by October.
The new sirens are then expected to be in action from April next year, replacing the region’s current older style siren network progressively installed since 2010.
More than 15,000 Northlanders shifted to higher ground on March 5, 2021, after an 8.1 earthquake in the Kermadecs in what was the event’s biggest regional tsunami evacuation nationally.
Northland currently has 205 existing sirens - New Zealand’s biggest tsunami siren network - that will be in action until the new Danish-designed system kicks in.
Northland Civil Defence emergency management specialist - tsunami projects Brendon Gray said the replacements would not mean loss of public safety.
“Even though the number of new sirens is less than half of the existing ones, due to the increased capabilities of the new sirens, all areas will see improved sound coverage from what they have currently.
“These upgraded sirens will provide timely alerts – even in situations where the current network wouldn’t be able to, such as during Cyclone Gabrielle where widespread power and mobile network outages impacted the region.
“Upgrading our siren network allows us to stay ahead of the curve. By meeting national and international standards for warning signals, we ensure our early warning system remains effective,” Gray said.
Whangārei Heads’ currently has 18 sirens but that number will halve. In the Bay of Islands, siren numbers will drop from 11 to eight in the Russell, Paihia and Ōpua area.
Gray said the new sirens were light years ahead of the region’s current network. They had improved sound and functionality.
Their shape means their sound, which is louder than the existing network’s siren, will be distributed more widely and less likely to be lost when strong winds carry it away before people have a chance to hear it.
Gray said Northland’s existing tsunami siren network was up to 14 years old, reaching the end of their lives and expensive to maintain.
Each new Danish siren unit costs about $60,000, compared with $2000 for existing sirens.
The new sirens will be erected on 8m high poles. They will have north-facing solar panels, a backup battery and control box as well as backup electricity connection.
Gray said a key plus for the new sirens was that they were not reliant on the region’s electricity network to function.
The new sirens are activated via the cellphone network or satellite if the phone network is out.
He said the new siren system also meant separate parts of the network could be individually activated, down to the level of a single unit if needed.
Sirens in the current network can only be set off as a whole unit.
The new sirens will also be able to provide voice warning messages in support of the sirens, indicating whether locals are hearing a test or whether the alerting is about a beach and marine threat only (for people on or near the water) or whether an evacuation is required.
The Danish-designed units have already been pre-programmed to be geolocated in their respective locations.
They have ingredients sourced from the United States and China.
The first of the new sirens purchased from Danish company HSS Engineering has just been installed off Whangārei Harbour’s Lower Port Rd.
Further installations will follow from Mangawhai to Cape Reinga along the east coast and at 10 key west coast locations including Ahipara and Waipapakauri on Ninety Mile Beach, Hokianga and Kaipara Harbour’s Ruawai.
Whangārei company Barfoote Construction has been contracted to build the concrete pads for and construct and install the new tsunami siren units.
The company’s Northland tsunami siren replacement project construction manager Tawanda Shiri, who hails from Zimbabwe, says the performance difference between the old and new sirens is like that between a tortoise and a cheetah.
Existing sirens will be in action until the new Danish-designed system kicks in after tsunami siren testing at the end of 2024/2025 daylight saving in April next year.
The new network’s sirens will sound the same as the existing ones.
Northland Civil Defence had been working with the Danish suppliers to identify the best spots for the new sirens whose functionality is already pre-programmed for their own specific geographic locations.
Northland ratepayers have paid for the sirens – Northland Regional Council $2.5m, Whangārei District Council $2.6m, Far North District Council $1.2m and Kaipara District Council $200,000. New Zealand’s National Emergency Management Agency NEMA put in $250,000.
Northland’s three district councils own the tsunami sirens in their area, which are managed by Northland Civil Defence Emergency Management Group on behalf of all Northlanders.
Whangārei will have 46 sirens across Whangārei central business district, Langs Beach/Waipū, Ruakākā/Marsden, Onerahi, Whangārei Heads, Whangaruru, Ngunguru/ Tūtūkākā and Whananaki districts.
Far North will have 42 sirens in the Bay of Islands, Kerikeri, Whangaroa, Doubtless Bay, Whatuwhiwhi, North Cape, Hokianga and Kaitāia districts.
Kaipara will have four sirens in Mangawhai and two in Ruawai district.
■ LDR is local body journalism co-funded by RNZ and NZ On Air.