Sirens are increasingly taking a backseat to mobile alerts in warning the public of tsunami threats to New Zealand’s cities. But in rural areas with limited connectivity like Northland, the siren system still holds the megaphone.
Last week, Christchurch followed Auckland in decommissioning most of its tsunami warning sirens, with other centres like Napier and Wellington shutting down or not having a tsunami siren network in the first place.
Christchurch City Council explained sirens were no longer considered suitable as the primary alerting method.
“They can cause confusion and delay communities responding, as warnings can be mistaken for different hazards,” a council spokesperson said.
The public can be distracted from education messages about responding to natural tsunami warning signs instead of waiting for official warnings, the council warned.
“Sirens also provide limited information on the tsunami hazard, are reliant on power and can be inaudible in windy conditions.”
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Theft and vandalism had rendered many of Auckland’s sirens unreliable, contributing to the Council’s decision to decommission most of them in 2023.
Yet in Northland, with its 3200km of exposed coastline which is home to remote communities, sirens aren’t just being retained, they’re being invested in.
Northland’s four councils – Northland Regional Council, Whangārei District Council, Far North District Council and the Kaipara District Council – all chipped in for the replacement project. NEMA (The National Emergency Management Agency) also contributed.
New sirens across the region
The louder, solar-powered sirens made in Denmark replace Northland’s ageing network of 200 sirens, with the rollout now in its final stages.
Once complete, there will be more than 90 new outdoor tsunami sirens installed across the region, from Mangawhai in the south to Pukenui in the far north.
Northland Emergency Management tsunami project specialist Brendon Gray said much of the region’s extensive coastline was at risk of tsunamis and that many of the remote, isolated communities on the coast had either limited, or no mobile coverage.
“Beyond coverage issues, we also face challenges with a fragile communications network and older, low-capability mobile devices being used by some of our communities.”
Sirens remain a “vital part” of Civil Defence’s toolbox for tsunami warnings, especially in areas where mobile alerts might be unreliable, Gray said.
“The sirens can be triggered via satellite and operate on solar power, making them resilient during power outages – such as those our region experienced during Cyclone Gabrielle or the Glorit Tower Topple – when mobile networks were disrupted due to power loss, not infrastructure damage.”
The new sirens also feature multi-tone alert sounds and pre-recorded voice messages to provide clearer instructions in an emergency.
Gray said there was a “strong demand” from remote communities for more sirens to be installed.
“However, at this time, there is no additional funding available to expand the network.”
Natural warning signs of a tsunami
A NEMA spokesperson said it was “really important” that people do not wait for an official warning if they experience the natural warning signs of a tsunami.
“If you’re in a coastal area and you experience a long or strong earthquake – that is, longer than a minute, or shaking that makes it hard to stand up – go to higher ground or as far inland as possible immediately. Then stay there until you’re given the all-clear.”
