A severe 6.2-magnitude earthquake has damaged houses, cut power to thousands, and caused office workers to evacuate their buildings in the Manawatu and Wairarapa areas.
The quake struck just before 4pm and was centred 15 kilometres east of Eketahuna at a depth of 33km.
GNS Science seismologist Caroline Little said the quake was felt from Invercargill to Auckland.
"Because of its depth it would be less severe than last year's Cook Strait quake, which was shallower."
Little said reports of higher shaking mainly came from Wellington, Kapiti and Manawatu but that was likely because of the bigger population on the west coast.
It would take time to establish which fault triggered the quake.
Although the possibility of another severe jolt could not be ruled out this afternoon she said it was likely aftershocks would lessen in intensity.
The magntitude has been revised several times over the afternoon. Nearly 30 weak to moderate aftershocks, mostly under magnitude 4, had followed the tremor and were centred near the Wairarapa towns of Castlepoint and Eketahuna.
QUAKE SPILLS CHEMICALS
Three people have been hospitalised after a chemical spill in Palmerston North.
The chemical spill on Illford Pl, which was caused by today's earthquake, involved materials used by gardening companies.
Palmerston North chief fire officer Rodger Calder said the two chemicals belonged to a gardening business.
The two drums holding the separate chemicals had fallen during the earthquake and split, causing the substances to mix, he said.
Three people had been hospitalised with lung and eye issues, he said.
While unsure exactly what the chemicals were, fire officers were going to collect them in drums before decontaminating the site.
Calder said the job should be done by mid-evening.
Residents have not been evacuated, but an odd smell was in the air.
'A SERIOUS JOLT'
Rebecca Harper, who lives in Tiraumea near Pahiatua in the Tararua district said it was the most awful experience of her life.
"Chimney down. Dog missing, everything in house smashed everywhere."
The quake was felt strongly in the Manawatu area with some people in Palmerston North reporting things toppling off their shelves. And one resident said concrete had sunk around their house.
Leeds St resident Maria Dalziel said her fence toppled "like a house of cards". When the shaking started, she grabbed her dog Sabre and ran into her front yard.
While there, the brick fence at the front of her property fell. "It just went like a house of cards".
Inside, her collection of 100 antique glass bottles had all smashed.
Jane Rushton of Tinui Station, very near the quake centre, said it was the strongest quake she had felt in her 23 years at the property.
Rushton was cleaning an historic cottage on the property when the quake struck.
"It certainly made the stock run, the buildings were creaking and the farm bikes parked near the cottage were rolling around quite a bit," she said.
"Its the first time we've had anything fall down and break. But the buildings seem fine. They're 100 years old, so they've probably seen worse in their time."
Heather Gowans and her partner Adrian Tutauha live in Solway, Masterton, about 40 km from quake centre.
"It was a really shaking and rolling - it went on for about 30 seconds. Adrian ran to grab the flat screen TV just in time. It just kept going and going and was swaying really bad. Everything was swaying and the place was creaking and groaning - but luckily nothing is broken."
There were concerns about rockfalls on state highways in the Manawatu area, with New Zealand Transport Agency staff still in the process of checking their safety following the earthquake.
NZTA spokesman Ewart Barnsley said there were reports the Manawatu Gorge road was down to one lane in places due to rockfalls, but this could not be confirmed.
It was not thought there was serious damage to the state highways network in the region but all road users were urged to use the roads with extreme caution.
"We've shut Pahiatua-Pongoroa Rd, we've got contractors out looking at a number of the bridges which is just precautionary and there is power out which has also taken out phones and internet," Tararua Council chief executive Blair King said.
"We've come through very well although I'm not sure about the south of else, Masterton area."
A large cliff slip near Mangaweka caused the Rangitikei River to change colour.
Mangaweka Adventure Company guide Anna Kasparova said dust and gravel could be seen from the campground falling from the top of Papa Cliffs into the river.
It had not been large enough to alter the way the river was flowing but it had caused it to turn milky-grey, she said.
Civil Defence issued an advisory on its Taranaki Facebook page advising Mangaweka locals to stay out of the river area.
The jolt also loosened a massive chunk of rock from the 162m high Castle Rock.
Castlepoint Store owner Devon Oakley said although some people had a few things knocked off shelves the township was much the same as before.He said the chunk was ''about the size of a bulldozer", but Castle Rock was still standing.
WORKERS STREAM OUT OF BUILDINGS
Office workers in Palmerston North ducked under their desks to avoid falling plaster during the quake.
Around The Square workers left buildings. Major damage was not obvious, but many were feeling the effects of the shaking.
Customer security guard at Downtown Shopping Mall Russell Jones was one of the first to evacuate.
"I was in the kiosk on the second floor watching all the TVs and I thought bugger the screens, I'm outta here.
"All the people in the mall, in the theatre, they left pretty quick and I think a lot of them headed to The Empire [hotel]."
Melanie Iosefa was in the NZI insurance building on The Square. Plaster fell onto a desk as the 15 to 20 workers in the building were forced to duck for cover on the floor.
The earthquake caused electricity to be cut to about 5600 in Tararua, Manawatu and Taranaki but Powerco expected to restore services tonight.
Powerco acting network operations manager Dean Stevenson said early reports indicated the damage was relatively minor.
About 1600 properties were still without power. "Powerco has sent field staff to inspect all its substations in the affected area and also to visit sites where we have had reports of damage", he said.
In Masterton, the 1925 Daniell's building on Queen St had been evacuated and two other older buildings appeared to be damaged.
Former Masterton mayor Garry Daniell, who owns the Daniell's building, said the damage appeared to be superficial but tenants had been evacuated and had found alternative accommodation.
He said it was unlikely the building would be able to be safely tenanted again. "I suspect the building the building will need to be demolished, I can't see that it would be economic to strengthen it."
In the Wairarapa civil defence controller Kevin Tunnell said so far there had not been any reports of injuries.
Tunnell said the Wairarapa civil defence centre had been activated and was collecting information, but so far damage to buildings sounded minor and was limited to Masterton, Tinui and Castlepoint.
Telecommunications company Vodafone reported outages in three cell sites, one of them in the Manawatu town of Feilding.
AIRPORT EAGLE FALLS
The quake was felt widely in Wellington. Hundreds of shoppers in Lower Hutt's Queensgate Mall left the complex following the tremor, which left people screaming and ducking for cover as items fell from shelves.
Some stores in the mall had closed.
A police central communications spokesman said no reports of major damage in the capital had been recieved.
A giant eagle suspended from the ceiling at Wellington Airport came down during the shake.
Lauren Stone, 19, was sitting under the eagle with a friend when the quake struck.
"It started shaking heaps and rattling, we jumped under the table," she said. "The eagle fell on top of us."
The wing of the giant eagle fell on top of the table and knocked it over, giving Stone a blow on the head.
"We ran away ... I definitely know I was hit on the head kind of thing but it didn't hurt or anything like that."
People were panicking: mothers screaming for their children. Initially, Stone thought a child may have been hurt.
"I don't think anyone really saw us, all the mums were screaming, it was quite panicked."
Natalie Julian, a staff member at the airport's Donut King store, was nearby when the giant eagle fell.
"I was having lunch about 20 metres away and I caught a glimpse of my workmates looking distressed. I saw the eagle swaying then heard a horrendous noise. It was like the roof was coming down."
She said the airport staff did a great job in the aftermath. "I'm a bit shaken, but I'm OK."
The airport had conducted an inspection of the runway. No damage had been revealed,and flights were not affected.
The quake was felt as a long rolling motion in Hawke's Bay, about 200km north of the epicentre, however police and civil defence have not fielded any reports of damage.
"It certainly went on for a while, but it was not the short, sharp jolt we would get worried about," said a Hawke's Bay civil defence spokesman.
Correction: This story incorrectly earlier reported that seals were killed in a rockfall at Castlepoint.