The public is being warned to stay out of the water and off beaches as Hawke's Bay faces the potential double whammy of tsunami and cyclone after effects 

The National Emergency Management Agency (NEMA) issued the advisory after a tsunami surge struck the east coast last night, causing widespread damage in a Northland marina. 

The tsunami formed after two maor events in the Pacific Islands - Cyclone Cody in Fiji and the eruption of underground volcano Hunga-Tonga-Hunga-Ha'pai in Tonga. 

Strong, unusual currents are already forming on the east coast after the eruption, and the arrival of swells from Cyclone Cody is expected to worsen the risk. 

Hawke's Bay was already on alert in anticipation of the after effects of Cody. 

Locals had been warned to steer clear of surf beaches such as Ocean Beach and Waimarama, as Cyclone Cody alone was expected to produce waves up to 4m near shore, and larger swells out to sea. 

Marine Parade, the scene of a drowning in December, is also a no-go zone if the heavy swells hit. 

After Saturday night's tsunami surge, NEMA – the former Ministry of Civil Defence & Emergency Management – issued a warning which stated: 

"We expect New Zealand coastal areas on the north and east coast of the North Island, the west coast of the South Island and the Chatham Islands to experience strong and unusual currents and unpredictable surges at the shore following a large volcanic eruption at Hunga-Tonga-Hunga-Ha'pai in Tonga. 

 

The calm before the storm at Te Awanga. Civil Defence has doubled down on a Cyclone Cody swell and current warning after a Tongan volcano eruption. Photo / Warren Buckland 

"Strong currents and surges can injure and drown people. 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 until this Advisory is cancelled. " 

The statement also advised: 

- Do not go to the coast to watch the unusual wave activity as there may be dangerous and unpredictable surges. 

- Listen to local civil defence authorities and follow any instructions. 

- Share this information with family, neighbours and friends. 

Campgrounds and a marina were evacuated overnight in Northland due to a tsunami surge that caused "significant damage" in Tutukaka, on the east coast of Whangarei district. 

Boats 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 the huge volcanic eruption in Tonga. 

On Friday, before the eruption, Hawke's Bay surf lifesavers had already suggested people avoid surf beaches for a few days. 

Dangerous swells and rips are expected from Sunday through to Tuesday. 

Surf Lifesaving NZ search and rescue manager Allan Mundy had said: "If you want to watch the waves go up the hill or sand across the road". 

"Just standing on the beach is a risk. If you are caught in that swell you will be pulled right out to sea with little chance of being rescued." 

A MetService spokesman said the ocean along the Hawke's Bay coastline would be dangerous, with breaking waves expected to rise to a minimum of four metres.