The administrator of the external Australian territory, about 1400 kilometres off the east coast, says there has been no damage to the island.

A 7.9 magnitude earthquake on Friday morning struck near the Kermadec Islands region to New Zealand's northeast, prompting thousands of Kiwis on the North Island's east coast to evacuate to higher ground.

It was one of several earthquakes to hit near the Kermadecs early on Friday.

The potential impact for Norfolk Island - to the west of the Kermadecs - began about 9am (AEDT) and was expected to last for several hours.

The Bureau of Meteorology warned of the possibility of dangerous rips, waves and strong ocean currents around the island, as well as "some localised overflow into the immediate foreshore".

A 64cm tsunami wave hit the island, but Norfolk Island Administrator Eric Hutchinson said there was no damage reported.

He said the island's 2000 residents had heeded the warnings of authorities, aided by text alerts through a newly-installed 4G network.

Police had earlier warned residents not to stand on the coast to watch the tsunami, and boats around the island were told to return to shore.

"Based on the advice we had earlier received ... we should be nearly past that threat," Mr Hutchinson, a former Tasmanian federal MP, told AAP earlier on Friday.

"I'm pleased with the way things have worked here."

The weather bureau said in a statement that the bay next to the island's pier was on Friday observed to twice "fill up" to a water level of up to 60cm.

But marine conditions around the island eased over the course of Friday and the tsunami marine warning was cancelled on Friday afternoon.

There was never a tsunami threat to the Australian mainland.

The BOM said in a statement that unusual wave activity, currents and tides may still affect some Norfolk Island beaches for some time.

"Tsunami waves are more powerful than beach waves of the same size. It is the power rather than the height that makes tsunami waves so destructive, hence dangerous to swimmers and boaters," the bureau said.

In New Zealand, workers, students and residents in areas like Northland and Bay of Plenty were being assisted by civil defence officials after authorities warned tsunami waves could reach three metres above tide levels.

Coastal areas under threat extended from the Bay of Islands to Whangarei and from Matata to Tolaga Bay, as well as Great Barrier Island.

Kiwis have since returned to their homes, with the threat passed.

Elsewhere, tsunami waves penetrated almost 30 metres inland at New Caledonia's Isle of Pines, while small tsunamis were recorded in Vanuatu, Fiji, the Cook Islands and Tonga.

In NSW, Tweed Heads to the state's north recorded a 10cm tsunami wave, while a 9cm tsunami wave was recorded at Illawarra's Port Kembla.

With Reuters

Australian Associated Press