Tsunami warning sirens have sounded and thousands of New Zealanders on the North Island’s east coast have evacuated to higher ground after a third earthquake.

There was gridlock in some cities in Northland and the Bay of Plenty as workers, students and residents fled.

Civil defence officials were on the ground to help people evacuate as authorities said tsunami waves could reach three metres above tide levels.

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By 9am (AEDT), the National Emergency Management Agency had warned residents to expect coastal inundation on the west coast of the North Island from Cape Reinga to Ahipara and on a much longera area of the island’s east coast, from the Cape to Whangarei and Matata to Tolaga Bay, in the Bay of Plenty.

Great Barrier Island is also included in the warnings.

“Strong and unusual currents and unpredictable surges near the shore are expected in the following areas,” AEMA said.

“This means a threat to beach, harbour, estuary and small boat activities.”

• See the latest NZ warnings here

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The deputy leader of the main opposition National Party, Dr Shane Reti, told RNZ he could see the sea going out in Whangarei, on the east coast of Northland.

There were also multiple reports of streams, rivers and the ocean emptying out in the region.

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The latest quake had a magnitude of 8.1 and struck the Kermadec Islands, north-east of New Zealand’s North Island.

It came shortly after a 7.4 magnitude earthquake in the same region.

Earlier, a large 7.2 magnitude earthquake struck about 900 kilometres away on the east of the North Island.

There were no reports of damage or casualties from the quakes.

Elsewhere, the Bureau of Meteorology confirmed a 64-centimetre wave had hit Norfolk Island on Friday morning. Further tsunami waves were  possible, the weather bureau said.

Tweet from @BOM_au

Earlier

A massive 7.4 magnitude earthquake has struck New Zealand just hours after a 7.3-magnitude quake was felt strongly off the east coast.

A tsunami warning has been issued, with the National Emergency Management Agency warning New Zealanders in coastal areas to brace for “strong and unusual currents and unpredictable surges at the shore”.

The US Geological Survey reported the magnitude 7.4 earthquake struck near the Kermadec Islands at 6.41am.

People living on the east coast in Northland, at the top of New Zealand, were warned to stay off beaches and out of the water following the Kermadec quake.

“People near coast from the BAY OF ISLANDS to WHANGAREI, from MATATA to TOLAGA BAY, and GREAT BARRIER ISLAND must MOVE IMMEDIATELY to nearest high ground, out of all tsunami evacuation zones, or as far inland as possible,” the National Emergency Management Agency said in a tweet.

Tweet from @NZcivildefence

It came after people near the coast from Cape Runaway to Tolaga Bay were told to evacuate amid concern the 7.3 magnitude quake that occurred at 2.27am local time (12.27am Australian time) on Friday could trigger a tsunami.

According to seismological agency Geonet, more than 60,000 people reported feeling the earthquake, which struck 95 kilometres east of Te Araroa.

Nearly 300 people described the shaking as “severe” and others said it was “extreme”, but most people described it as light.

“Hope everyone is OK out there – especially on the East Coast who would have felt the full force of that earthquake,” Prime Minister Jacinda Ardern posted on Instagram.

“She was a beauty, it really shook. I’m quite frightened, I’ve got no idea if there’s going to be a tsunami, it was massive,” Rex from Gisborne told Newstalk ZB’s Bruce Russell.

“It’s the biggest I’ve felt in a long, long time and I’m 80.”

Gisborne Mayor Rehette Stoltz said the quake has woken “everyone” up.

“Our Civil Defence teams got into action immediately to make sure everyone was safe and sound.

“I’ve heard reports of little bits of damage, nothing major at this stage.”

Tweet from @NZcivildefence

Helen in the Chatham Islands said it was the biggest earthquake she has ever felt.

“It went on and on and on. I’m in the old stone house and I didn’t know where to stand because it’s all rock. I’ve never felt one so big – it must be massive across New Zealand. It died down and then went on and on again,” she told Newstalk ZB.

There was no immediate report of damages from the quake that occurred at 2.27am local time (12.27am AEDT) on Friday.

GeoNet pegged the quake at a magnitude of 7.2 with a depth of 94 kilometres.

The Joint Australian Tsunami Warning Centre said there was no tsunami threat to the Australian mainland, islands or territories.

-with AAP