Images of the violent volcanic eruption near Tonga are "hugely concerning", Prime Minister Jacinda Ardern says. 

In a social media post Ardern said communication had been difficult following the eruption of the underground volcano Hunga Tonga-Hunga Haʻapai last night. 

The violent eruption from Hunga Tonga-Hunga Haʻapai sent ash, steam and gas up to 20km into the air and has caused untold damage in the Pacific nation. 

"[Our] defence force team and Ministry of Foreign Affairs are working as we speak to establish what's needed and how we can help," the post from Ardern said. 

"I'll be giving an update again at 3pm. Till then, I know we are thinking of our pacific friends and family." 

The NZ Defence Force earlier said it was standing by for any request for assistance from the Tongan government. 

Little is known yet about the impacts on Tonga itself as power is out and communication lines are down. 

Last night locals posted video of a tsunami flooding the coastline, surging through houses and a church. "Pray for us," wrote one Tongan resident on social media, as people fled to higher ground amid panicked screaming. The sky turned black as the cloud from the eruption covered the sun, and much of the country is thought to be covered in ash. 

Tsunami alerts around the Pacific after eruption 

The eruption has sent shockwaves around the world and put many countries around the Pacific on high alert for tsunamis or surges, including in New Zealand. 

Fresh warnings have been issued this morning by Civil Defence, which says people on the north and east coast of the North Island, the west coast of the South Island and the Chatham Islands could all likely to see strong and unusual currents and unpredictable surges at the shore. 

Tutukaka Marina and some campgrounds in Northland were evacuated overnight due to a tsunami surge that caused "significant damage", sinking a number of boats and badly damaging others. 

The marina has been evacuated this morning as more big waves may be on their way, officials say. 

Many boats at Tutukaka were "completely destroyed" by a wave around 2m higher than the high tide line - believed to be caused by a combination of Cyclone Cody and a huge volcanic eruption in Tonga. 

Tutukaka locals have been at the marina this morning attempting to clean up the extensive damage, but they have now been asked to leave. 

Numerous boats have been sunk or destroyed by last night's huge surge at Tutukaka marina. Photo / Tania Whyte 

While no further tsunami warning has been issued, officials are asking everyone who is not needed to leave the space as they are aware of big waves coming in. 

They say the evacuation is a precautionary measure - they do not want more people in the area to add to the hassle. 

Civil Defence is warning of further strong surges this morning and in coming days, saying "locations that have previously been calm can suddenly experience unpredictable surges". 

"Strong currents and surges can injure and drown people," the latest Civil Defence alert says. 

"There is a danger to swimmers, surfers, people fishing, small boats and anyone in or near the water close to shore. 

"People in or near the sea should move out of the water, off beaches and shore areas and away from harbours, rivers and estuaries," it says. 

Flooding of coastal land areas was not expected. 

Numerous boats have been sunk or destroyed by last night's huge surge at Tutukaka marina. Photo / Tania Whyte 

Millions of dollars of damage is expected at Tutukaka following last night's huge wave - including damage to the marina itself. Photo / Tania Whyte 

Last night Civil Defence Northland issued a tsunami warning for people living along the coastline following the violent eruption of underground volcano Hunga Tonga-Hunga Haʻapai. It warned of "strong and unusual currents and unpredictable surges at the shore". 

But it appears some people were still caught unaware last night. Pictures from Tutukaka Marina show boats loose from their moorings with visible damage to their hulls. 

Civil Defence is warning sightseers to stay away as the hazardous surges are continuing, and are likely along the entire east coast of Northland. 

Local man Tim Alexander said his boat was among about 30 that had been destroyed although it was hard to tell at this stage. 

Tutukaka local Tim Alexander, pictured with his boat Justice, estimates 30 boats at the marina have been destroyed. Photo / Tania Whyte 

His own boat was a complete loss, he said. The wave had cleared the breakwater which was about 2 metres higher than the high tide line. 

He had several friends who lived on their boats but all were safe. "We're very thankful – nobody was on their boat, they heard it coming in. From what I understand it was a big event, they got out really fast." 

His biggest concern was that there was warning from Civil Defence ahead of the surge, with no phone alerts or tsunami siren. He had seen the general warning put out on the news but had taken little notice given there was no tsunami alert in the area. 

"We've got a tsunami alert system here in Tutukaka but we had no warning whatsoever. 

"There have been multiple alarms in the last 24 months and we've had to evacuate but there's been no damage to the marina, and almost [no] waves – this time there was no notification and it's completely destroyed the entire marina." 

One Tutukaka local, whose boat was among those destroyed, was concerned he received no Civil Defence alert on his phone. Photo / Supplied 

He estimated damage to both the marina and the boats was in the millions of dollars. 

Just before 9am people were tending to their property as well as securing rubbish to stop it floating out to sea. Alexander said the surges seemed to have subsided this morning - although Civil Defence has warned fresh waves could come without warning. 

Around 10.30am a reporter at the scene said officials were evacuating the area for health and safety reasons, and asking people to leave the marina if they were not strictly needed. 

It's not yet clear what those health and safety concerns are as there is no fresh tsunami warning - however the marina jetties are extensively damaged. 

Civil Defence is evacuating Tutukaka Marina this morning as a precaution with more big waves expected. Photo / Avina Vidyadharan 

Officials are asking people to leave the marina if they are not needed. Photo / Tania Whyte 

A half-sunk boat at Tutukaka marina. Photo / Alison Jeffs, Facebook 

A number of people on social media are also reporting they did not get a civil defence alert to their phones prior to the surge. 

On Saturday evening water was sucked out of half the bay followed by "massive surges" up into the estuary, Rebecca Hendl-Smith tweeted. "Pretty scary and I reckon most of us on the Sandspit evacuated soon after that." 

Police said they had attended a number of tsunami-related jobs in the Far North, with the first call coming in at 11.20pm from Te Rere. 

"Police, fire and Coast Guard assisted in evacuating some boats from [Tutukaka] marina after large waves surged ashore. The waves have also damaged some pontoons and boats moored at the marina," a spokeswoman said. 

She was unsure how many people had been evacuated. 

Abe Ropata helps clean debris from the props of the Silver Fox at Tutukaka Marina. Photo / Tania Whyte 

Civil Defence had also advised of a campground being flooded at Mahinepua Bay. Police had attended the campsite to assist with evacuations, she said. 

Civil Defence believes the surge was caused by a combination of Cyclone Cody and the Tonga eruption. 

Multiple boats have been destroyed in a surge at Tutukaka in Northland overnight. Photo / Supplied 

Just before midnight Civil Defence Northland said it was aware of "a number of impacts" that had taken place along Northland's east coast. 

"These impacts have generally been localised and either in, or close to, the water, but in at least one instance have caused significant damage: Tutukaka Marina, where there has been damage to a number of boats and marina structures, with people who live on their boats within the marina evacuated as a precaution." 

This morning Civil Defence said daylight confirmed the extent of the damage, and it was "sad news" for a number of boat owners. 

Civil Defence says the damage will be properly assessed today. Photo / Supplied 

Frequent and strong surge activity was continuing this morning and was likely to be happening along the whole of Northland's east coast. 

"Experience from past tsunami events has been that this activity can continue for a number of days, and that locations that have previously been calm can suddenly experience unpredictable surges. 

"Please continue to take extreme care in and around the water and don't give in to the temptation to go sightseeing - the combination of the effects of Cyclone Cody and already-heightened sea levels with tsunami surge from the Tonga eruption has the potential to create hazards that have not previously been experienced." 

Civil Defence said last night a number of coastal campgrounds had also been evacuated or campers relocated because of incoming waves. 

"It's a challenge to distinguish the effects of the storm surge generated by Cyclone Cody, from currents/surges resulting from the volcanic eruption in Tonga, but our best assessment at this stage is that the two combined in a number of specific places, with local landforms also playing a part," Civil Defence said. 

"Damage assessment/cleanup efforts will begin in earnest in the morning at Tutukaka Marina in particular (noting that Tonga is also facing a major cleanup)." 

One Tutukaka local, whose boat was among those destroyed, was concerned he received no Civil Defence alert on his phone. Photo / Supplied 

People were warned to take great care around beachfronts and estuaries as past tsunamis had caused unpredictable effects for a number of days, while Cyclone Cody was also still causing large waves. 

"It's not a time for taking chances". 

Civil Defence thanked everyone who had helped last night including emergency services, community members, iwi, and businesses.