Tsunami sirens have activated in Whangārei, but no one is yet sure why.
Northpower is investigating the cause, but said there was no testing or work on the sirens planned.
Civil Defence confirmed on Facebook that there are no current tsunami warnings or alerts in place.
Tsunami sirens across Northland were tested on April 3, at the end of daylight saving.
The sirens are tested every six months, at the beginning and end of daylight saving time.
