There are growing concerns about a niche subculture of “sirening”, which has led to a rise in tsunami siren thefts across Auckland.

In the past year, 65 tsunami sirens have been stolen across Auckland, an increase of 21 since the last update in October last year.

During the last update, an Auckland Emergency Management (AEM) spokesperson said it was suspected the units were used for “siren battles” or “sirening”.

The sirening subculture involves attaching the stolen sirens to the front of a car or bike and playing music through them.

Sireners, who are usually part of “crews”, play a mix of music with high treble suitable for the siren speakers and battle across Auckland most Saturdays, with crews vying to see whose sirens are loudest and clearest.

The recent release of numbers comes just days before the next bi-annual tsunami siren testing this Sunday, June 4.

AEM head of capability and public awareness Adam Maggs said in October the sirens “are of no use” for any other purpose than alerting the public to danger.

“The loss of sirens means that the audible warnings for a tsunami threat at these locations may not be functioning at full capacity or as you might expect – for example, some areas may have fewer operating sirens,” Maggs said.

The money would be funded from ratepayers’ pockets to fix and replace the sirens, Maggs said.

“They are also not an ‘off-the-shelf’ product, which means they cannot simply be replaced.”

It was fortunate the sirens were not the only means to alert people to the threat of a tsunami, Maggs said.

“Warnings will be sent by Emergency Mobile Alert [messages to your mobile phone], 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 or strong, move inland or to higher ground immediately.”