A strong quake has been felt across the country this afternoon.

The 6.4 magnitude quake was centred 35km north-west of Kaikoura, at a depth of 83km, GeoNet said.

GeoNet described the quake as "strong".

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Richard from Blenheim told Newstalk ZB when the rolling quake hit some of his pictures swung out.

"I think it would have been about 15 seconds."

Sue, who lives in Cheviot, which is 70km from Kaikoura said she was "surveying" her home following the quake.

"I've got hanging things in my kitchen and they are still swinging."

Ms Little said the intensity of the quake was "strong".

She said it was likely things had fallen off shelves, and there could be damage to buildings, however it would not be structural.

Meanwhile, there have been reports of problems with mobile networks.

On twitter Spark said: "The mobile network congestion that's arisen after the #eqnz shakes is affecting other parts of NZ. Thanks for your reports."


In a statement Spark said it currently had a nationwide outage on mobiles, internet and landlines due to increased traffic following the Kaikoura earthquake.

It said the outage was affecting all parts of New Zealand, and there was no further information available at this stage.

"We apologise for any inconvenience."

'Scared and shaken up'
Public information manager for the Kaikoura Civil Defence Rachel Vaughn said the quakes had left those in Kaikoura "scared and shaken up".

"We got two very strong jolts followed by a lot of shaking. We went under our desks and waited for it to stop.

"People were evacuated out of shops but they are going back to business as usual now."

Ms Vaughn said although there had been no reports of damage - it did not mean there was no damage.

"Our engineer has gone to check infrastructure, including sewer and water supplies, making sure our pump stations and everything is working.

"I saw there has been reports of stuff falling off shelves, but no reports of damage."

Rail services suspended
A KiwiRail spokesman said all rail services from Picton to Christchurch, and Christchurch to Arthur's Pass were suspended pending safety checks to track and infrastructure.

He said the Coastal Pacific service was halted at Kaikoura and the TranzAlpine service was stopped at Arthur's Pass.

Tranz Metro services in Wellington have now resumed following safety checks.

"Customers have been advised to expect delays as services resumes."

A man who felt the quake told Newstalk ZB: "It just kept going and rolling around, it must have been going for 20 or 30 seconds or something like that."

A woman said: "I thought it was a truck you know that rumbling noise and then the house just swayed and swayed believe you me, and I thought where am I going, so I just went and stood under the doorway on my deck."

Herald reader Paddy Brocherie wrote in to describe the quake as "the longest quake I've ever felt and I live in Christchurch".

"Bad, bad, bad."

Susan Allan said she felt the earth move in Riwaka - a "sharp rolling jolting for approx 30 seconds".

The quake shook the house, but there was no damage, she said.

Further north in New Plymouth, Victoria Brooks felt the shake "very nicely".

Rachael King, the award-winning New Zealand author of books like Magpie Hall and The Sound of Butterlies, tweeted about the earthquake.


'The deeper the quake, the more rolling the shaking'
Public information specialist for GeoNet, Caroline Little, said the magnitude 6.4 quake was centered 40km north west of Kaikoura.

She said those in Kaikoura were sure to have felt the tremor.

"The deeper the quake, the more rolling the shaking is rather than that violent shaking - they definitely would have felt it."

Ms Little said there were reports of the quake being felt as far south as Timaru, and as far north as Hamilton.



She said this was for "light shaking".
It was likely the quakes were related to two quakes that shook the country yesterday, Ms Little said.

Yesterday's quakes were located east of Seddon, Marlborough, and were widely felt across the strait in Wellington.

The first came at 10.36am and was recorded 20km east of Seddon. It was 23km deep and had a magnitude of 4.4, GeoNet said.

The second hit six minutes later at 10.42am and was more intense and prolonged than the first.

It was recorded 15km east of Seddon, had a magnitude of 5.1 and was described as strong by GeoNet.

"I'd say that these are all related in that area and are related to the 2013 quakes as well around the Cook Strait and Seddon area," Ms Little said.

Jacqui Harnett, from Genevieves gift shop in Kaikoura, said the "rumbling" quake had caused things to come off the shelves.

"There was the big one and then there was another smaller one."

"I'm not a good person to talk to about earthquakes because I don't normally feel them. But I couldn't help but feel this one.

"From what I have heard the whole of New Zealand felt it."

Ms Harnett said there were only tourists in the town centre at the moment and very few locals.

"The tourists came in and asked us if it was an earthquake because a lot of people from overseas don't get earthquakes."