Siren battles may be at the heart of Auckland's tsunami siren vandalism problem, says Auckland Council.
In the past six months, 31 siren units have been stolen across 13 different sites.
Of those, 22 were taken from west coast beaches including Huia, Whatipu, Karekare, Piha, and Te Henga. Another nine sirens were stolen from east Auckland beaches.
Auckland Emergency Management's acting general manager Adam Magg said while tsunami sirens look like they would be great for playing music, they can only be used for warnings.
Magg said, "We suspect they are being stolen for siren battling and installation on vehicles, but these sirens are specifically designed for alerting. They are otherwise useless. Their voltage makes them incompatible with vehicle systems and for playing music."
Siren battles have been popularised in Auckland since the early 2000s, with youths attaching battery-powered speaker systems to their vehicles or bicycles. Each group would then play their music as loud as possible, each vying to outdo the other.
Magg told Newshub the council was looking for a way to deter the vandalism which has been increasing since May.
"Ongoing theft of the region's sirens is unacceptable and must stop. In recent weeks this behaviour has escalated, affecting a significant number of sites along the west coast."
Magg said the vandals' actions were both expensive and dangerous - putting the lives of New Zealanders at risk.
"Not only is it dangerous for the public, but those trying to remove them are risking their own safety. The units are typically mounted three-quarters up power pole structures and are directly attached to the electricity supply.
"You'd have to deal with live wires to get them off."
The areas impacted were a cause for concern too. "The loss of sirens means the audible warnings for a tsunami threat at these locations may not be functioning at full capacity as you might expect - for example, some may have fewer operating sirens."
Magg wanted to reassure the public that there were alternative ways to receive tsunami warning alerts.
"Warnings will be sent by emergency mobile alert, broadcast on radio and television, or via the news media, and social media platforms," he said.
"And of course, if you are at the coast and feel an earthquake which is long and strong, move inland or to higher ground immediately."