Four Far North tsunami sirens that experienced problems during today's tsunami evacuation alerting would be investigated, Far North Mayor John Carter said.
The former Minister of Civil Defence said investigation into the issues with the sirens would be part of a post-event debrief.
Te Kao, Te Paki, Te Hapua and Ngataki sirens on the Aupouri Peninsula not far south of Cape Reinga were affected by a Top Energy power outage.
Tsunami sirens are among essential alert technology in these isolated and remote Far North communities. Cape Reinga is New Zealand's closest mainland point to the Kermadec Islands about 1000km to the north.
Northland Civil Defence said, while the evacuation was still in force, people in those areas should remain evacuated, regardless of what the sirens may or may not be doing. They were told they should await the official all-clear which would be communicated via mobile phone alerts and the Northland Civil Defence Facebook page.
Carter said issues with sirens were among lessons to be learned from today. He said communicating tsunami evacuation warnings to far-flung remote Far North communities was among the day's biggest challenges.
"Today's biggest challenge was making sure everybody was aware of the alerts."
Issues with internet access and mobile phone connectivity in some communities meant an extra challenge for the Far North.
"There are always people who do not get the advice," he said.
This meant door-knocking and going around local communities notifying people was also required.
He and other councillors had gone around their people making sure they knew of the alerts.
Northland's Civil Defence provision had worked well today across the raft of people involved, Carter said.
The day's sequence of tsunami evacuation alerting had also gone well. He said the people of the Far North, Northland and New Zealand could all be congratulated for the way they had responded during the tsunami warnings and evacuations.