A magnitude 5.8 earthquake has hit near the South Island resort town of Wanaka, with one resident saying it seemed to "go and go and go".
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The quake hit at 2.29pm and was centred 30km north-west of Wanaka, in the Matukituki Valley, at a depth of just 5km, GeoNet said.
Within minutes of the quake hundreds of people across the country had left messages on GeoNet indicating they had felt the jolt.
Former Wellington man Kieren Drabble said the quake was "a goody".
"It's certainly one of the biggest I can remember," he said.
"It wasn't really sharp, just very, very rolly. It just seemed to go and go and go."
Mr Drabble sheltered in a doorway during the quake and had just started moving away when an aftershock hit.
Mr Drabble and his family moved to Wanaka from Wellington only a few months ago, and the irony of a quake hitting there did not escape him.
"I moved out of Wellington to get away from earthquakes," Mr Drabble said.
Quake 30 km north-west of Wanaka, intensity severe, approx. M6.0, depth 5 km http://t.co/94KdxuHnuN Mon May 4 2015 2:29 PM (NZST)— GeoNet (@geonet) May 4, 2015
A police spokesperson said there had been no major reported damage, although a few windows had been broken.
Wanaka Four Square manager Cam Sinclair said everyone in the store got a fright, and there were wine bottles and shelves in the store.
"Kept rocking for about 40-off seconds I suppose, or a bit longer, and then knocked stuff off the shelves," Mr Sinclair said.
"Everyone evacuated the premises. Most of the other buildings in the nearby block, everyone had evacuated as well.
"It just gave everyone a hell of a fright, I think."
Children at Hawea Flat School, just a few kilometres from the epicentre of the quake, dived under their tables when the shaking started.
School administrator Leanne Harling said she was struck by how noisy it was.
"Well I'm in an office with metal filing systems and, even though they're attached to the wall, the noise because they were shaking was pretty loud," she said.
"It felt like it went on for about a minute. We've got big trees in the school grounds and there was no wind at the time so it was really weird seeing them swaying."
The earthquake was particularly upsetting for two children who had moved to the area following the Christchurch earthquakes, Ms Harling said.
Aspiring Holiday Park receptionist Lauren Roney said the only damage was to a picture frame, which fell down.
However, her guests had been left rattled.
"Some people staying with us have not been in an earthquake before so they came running down to see what was going on as it was still rumbling," she said.
"But everyone's safe and okay and some are a bit shocked."
Ms Roney said it was the biggest quake she had felt in her 18 years' living in Wanaka.
Wanaka resident Jocelyn Toomey said she was at home up a ladder painting when the quake struck.
"It felt like a big rumble and a rolling movement, and it went on for quite a while," she said.
"The lights are on pendulums and they were swinging quite dramatically.
"Nothing fell down but you could feel it inside you and it was rolling, and then it calmed down and then it went again, it was like there was another one."
Glenis Palmer was at work in a jewellery shop when the quake hit.
"We felt the building shake and it sounded like someone had dropped something upstairs."
Jess Harkins said the quake was a "roller" in Arrowtown.
"The mountains sounded like a freight train," she said.
'Louder and louder and louder'
Ally, who lives 17km from Wanaka, said the quake rattled through the valley.
"We were standing outside and heard this kind of train kind of sound, or maybe a big lorry, and it just got louder and louder and louder and came down the valley," she said.
"Really violent shuddering and shaking. It seemed to go on forever but probably only a minute."
Wanaka District Councillor Calum MacLeod said the rock-and-rolly quake started with an audible crack and sounded like a freight train.
The quake was the biggest in the area for six or eight years but did not do any damage to his wooden house or to the town's cinema, where there were bottles of wine on racks, he said.
The quake was also felt in Timaru and Greymouth, where it was "real gentle but quite a long shake".
"I kept wondering if it was going to be the big one," Maryanne said.
Wanaka community board chairperson Rachel Brown said the town felt like they had a lucky escape after the quake.
She was in Wanaka's Mitre 10 store car park when the quake struck and for the first few seconds she thought someone was pranking her by jumping on her bumper bar.
Ms Brown said people then poured out of the hardware store, but there seemed to have been little damage.
When she went to pick her children up shortly after from the Hawea Flats School she said there were more parents than usual and a kind of "this could have been bad but it wasn't" euphoria in the air.
She said the quake made her think of the situation in Nepal, but said in the end "the mountains hiccupped and we're all very lucky".