Civil Defence has downgraded New Zealand's tsunami warning to an advisory.
However, the Ministry warned there was still a likelihood of surges and rapid sea level changes in New Zealand following a massive earthquake in Chile which killed at least 300 people. The surges could continue for up to 24 hours after the initial wave arrivals.
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"Wave heights could be larger than what we have currently experienced but within the threat levels and wave height estimates that have been previously forecast," it said in its latest statement.
Surges have been reported at beaches around the country, including in Northland, East Cape, Canterbury, Otago and Chatham Islands.
Strong currents were still expected in harbours and restricted waterways such as estuaries and river mouths while there was still a possibility of surges between one and three metres at the Chatham Islands and Banks Peninsula.
"This represents risks to people in boats and on beaches for coastal communities in the east coast of the North and South Island and particularly Chatham Islands and Banks Peninsula," national Civil Defence said.
Tsunami expert and Canterbury University emeritus professor of coastal studies Bob Kirk said based on the first two tsunamis in Lyttelton harbour today, a third was likely around 5pm, which is high tide.
The first tsunami was "of the order of 2m" in height. If it had hit at high tide it would have caused extensive flooding along the coast, around the Avon-Heathcote estuary, and in river mouths.
"That first wave is not chicken feed at all, that's a big one. If you were to mentally translate that to the. . .same position with the predicted high tide you can see 1m 60 or so of water there that would be over and above the high tide, and that's not trivial.
"They'll (civil defence) be watching this closely. It's a bit of a tense time until midnight tonight," Kirk said.
There was no guarantee the gap between the surges would remain at two hours, he said.
In the May 23, 1960 event, a 5m tsunami at high tide sent waves rushing into the estuary at 25km/h, flipped a cabin cruiser, set yachts adrift and left dinghies on the main road to Sumner.
Northland Civil Defence spokesman Matt Johnson said they were still experiencing "reasonably interesting fluctuations in sea levels and tidal surges" but expert advice suggested the main threat had passed.
They were not concerned about the possibility of high tide adding to the threat of the surges, saying the initial wave action had arrived not long after high tide this morning.
They still advised Northlanders to be cautious.
NZ FAMILY CAUGHT UP IN QUAKE DRAMA
Christchurch man Sean Gosling had a nervous wait as he sought news of his wife and daughter who were near the epicentre of last night's devastating earthquake in Chile.
Chile was rocked by an 8.8 magnitude quake last night which has killed at least 214 people, knocked down buildings and prompted a Pacific-wide tsunami warning.
Evelyn Fabiana Matamala Rojas and Paloma Sefia Gosling, 4, had been in Concepcion, the closest major settlement to the earthquake's epicentre for three weeks visiting Evelyn's family, Mr Gosling said.
The desperately worried father and husband had been frantically trying to get hold of the pair, trying friends, embassies, and any other methods of communication in a bid to try and track them down.
This morning, a friend in northern Chile, who had been given a long list of numbers to try by Mr Gosling, had managed to get hold of Evelyn's father who lives about 20 minutes out of Concepcion.
KEY SAYS NZ READY TO HELP
Prime Minister John Key today expressed sympathy on behalf of New Zealand, saying he was "shocked by the devastation".
"More than 200 people have died, but it's clear from media reports that the toll may rise.
New Zealand's government would priovide assistance to Chile on request, he said.
SOME GO AGAINST ADVICE
There have been numerous reports of people heading to the coast to watch the tsunami.
Coastguard Northern Region duty officer John Cowan, said people should head to high ground.
"Stay away from the beaches. Don't go out on the water and if you are already out on the water up anchor and head to deeper water at least half a mile off shore."
Dunedin Police are patrolling the eastern coastline to ensure that people keep away from beaches and low lying coastal areas following a national tsunami warning.
TSUNAMI WARNING DISRUPTS THE COUNTRY
Further south, the Marsden Point Oil Refinery, which is right on the coast, was briefly put in an emergency shutdown while Ports of Auckland closed the nation's biggest port. Around 100 vessels, including Dawn Princess, left wharves to wait out the surges in the Rangitito Channel.
The ocean at a beach south of Christchurch receded dramatically, leaving fish stranded on the sand.
Press reporter Martin van Beynen said the water at Purau Bay in Banks Peninsula withdrew over about five minutes. On some parts of the deserted beach the water was 100 metres from where it should have been.
"You could see the odd fish flapping about on the sand," he told Stuff.
The water slowly pushed back in before withdrawing again, he said.
In Timaru, hand-written "cancelled" signs and closed car parks were the first many people visiting Caroline Bay knew of this morning's tsunami alert.
With the tsunami due to reach the South Canterbury coastline just after 9am, the Sunday morning farmers market on Caroline Bay was cancelled as was a begonia show being held in the Caroline Bay Hall.
A children's triathlon to be held this afternoon has also been cancelled in line with civil defence advice to stay away from coastal areas for the rest of the day.
In Poverty Bay Whispering Sands Beachfront Motel owner Peter Martin had been watching the sea in Gisborne and said there had been a noticeable drop in the water level.
"The water went out a wee bit and when the water dropped the water came out of the river water ... the water's looking quite dirty," he said.
"I think now the ... sea level's starting to come back in," he said.
There had been a voluntary evacuation notice issued but locals were pretty relaxed.
"I don't think people have gone as crazy as they have the past two times," he said.
Auckland coastguard radio operator Emma Millen said around 100 boats are floating in the deep water to wait out projected tsunami surges.
"It's basically all the boats that have been moored in the small bays over the weekend, they had to get out of the shallow water and steam into the harbour," Ms Millen said.
Around the country many events were cancelled, including the secondary schools dragon boat competition in Wellington, a nude photo shoot at Worser Bay in Wellington, and sports events.
On the Chatham Islands, residents have seen big changes in water level. Chatham Islanders took to what little high ground there is.
Bernadette Malinson, of Flower Pot Bay, on Pitt Island in the Chathams, reported significant surges this morning which emptied the bay and revealed the full height of the piles on the wharf there.
"The bay empties right out. It takes about a minute and a half and then it surges back in, in about the same amount of time,'' she told Radio New Zealand.
"The surges have been getting bigger - at least 2m at present.''
The tidal activity, which had been going on all morning, had not caused any damage, she said.
In Akaroa, on Canterbury's Banks Peninsula, tidal surges of up to 30m were reported.
In the space of 10 minutes, the water receded almost to the swimming pontoon off the main beach in the township and then returned quickly, one witness said. Just as in Pitt Island, the pier in Akaroa was fully exposed.
Sea levels along the Gisborne coast had dropped dramatically, prompting authorities to close roads to beaches and clear away sightseers.
Waikanae Beach Holiday Park manager Diane Ross said the sea suddenly receded about 9.20am.
It was almost high tide when the water pulled out to below the low tide mark.
It dropped about 1-1.5 metres in a matter of moments, Ms Ross told Radio New Zealand.
The water went "very, very brown", indicating that it was being stirred up by swirling currents, she said.
All the holidaymakers at the campground had been evacuated early this morning and were watching the action from a marae at nearby Kaiti Hill.
Gisborne Civil Defence controller John Davies confirmed the witness reports, saying the sea had dropped about a metre and while it had not surged back in, there was "unusual'' wave activity happening.
In Hawke's Bay, the coastal settlements of Ocean Beach and Waimarama have been evacuated, and police were door-knocking at Haumoana and Te Awanga, warning residents it would be a good idea to leave.
Eleven houses right on the beach at Te Awanga were particularly at risk. One of those residents was recently prosecuted for building an illegal sea wall to stop the heavy seas eroding his backyard.
Ken Gledhill of GNS Science said New Zealand was not in the main beam of the tsunami, which was headed for Japan.
MINISTER PRAISES RESPONSE
Civil Defence Minister John Carter was hailing the response to this morning's tsunami saying last year's Samoan tsunami alerts, which prompted heavy criticism, had been "a very good learning curve".
"I'm very pleased with the way in which Civil Defence has responded to that and it's been very evident that the structure right across the board understood the need to improve and has done."
The communication between Civil Defence and local emergency authorities, such as police, the fire service and regional coast-guards, had been excellent, Mr Carter said.
"The media have also played a great role in helping us with this issue and alerting New Zealanders to the potential risk."
"All in all it's a big step up from where we were just four months ago.
- © Fairfax NZ News