While New Zealand Prime Minister John Key says it is "a miracle" no one was killed in the Christchurch earthquake, experts believe it was the country's strict building codes that prevented mass fatalities.

The 7.0 magnitude quake brought down building facades, buckled train lines and caused damage estimated at more than a billion dollars in New Zealand's second largest city, but did not result in the high death tolls seen in similar disasters worldwide.

The statistics just this year make grim reading: at least 220,000 dead in a 7.0 magnitude quake in Haiti last January, more than 2,000 killed when a 6.9 magnitude tremblor struck northwest China in April and more than 500 lives lost when an 8.8 mega-quake hit Chile in February.

Officials say Christchurch residents were lucky the quake occurred before dawn on Saturday, when most were asleep in the relative safety of their homes. A few hours later and the streets would have been thronged with Saturday morning shoppers.

But they have nevertheless expressed amazement that no one died when such a powerful seismic jolt struck so close to a city of 340,000. So far, there have only been two reports of serious injuries.

"The only conclusion you can draw is that it's a miracle nobody was killed," said Key. "Parts of the city look like they've been put in the tumble dryer."

New Zealand, which sits at the junction of two tectonic plates, is no stranger to earthquakes and experts said it had learned harsh lessons from a 1931 disaster at Napier, when a 7.8 magnitude tremor killed 256 people at Hawke's Bay.

The director of the Joint Centre For Disaster Research at Wellington's Massey University, David Johnston, said that resulted in the implementation of stringent building standards.

"There's no doubt it's a very, very significant reason why there wasn't more destruction," he told AFP.

"In developing countries we've seen the wholescale collapse of buildings. In Christchurch, it's been the older buildings on the outskirts of the CBD that have been worst affected but the vast majority of structures have maintained their integrity.

"It's a testament to the efforts in New Zealand since 1931."

Pieter Burghout, chief executive of BRANZ, an industry-funded construction safety research body, said the most severely damaged buildings in Christchurch were made of bricks and mortar, materials that do not cope well with earthquakes.

He said modern homes in New Zealand were mostly constructed around light timber frames, which provided flexibility when a quake hit.

"I've seen pictures of a house in Christchurch which fell off its foundations but it was still structurally sound," he said.

Burghout said New Zealand was among the world leaders in earthquake-resistant design and BRANZ had a large research facility in Wellington where a full-scale house could be built so testers could "shake it to bits" in a simulated tremor.

He said new office blocks in the country were built on isolated foundations, meaning they rest on a bed of rubber shock absorbers or ball bearings "so they can wobble around a bit if the big one comes".

Many historic buildings have been retro-fitted with earthquake dampening devices, a measure the Anglican Dean of Christchurch Peter Beck said paid off when the city's Anglican cathedral escaped with only minor damage on Saturday.

"Thank God for earthquake strengthening 10 years ago," he told national television.

Burghout conceded New Zealand's building standards were expensive, making them all-but-impossible to impose in developing nations such as Haiti, one of the world's most impoverished nations.

But he said the strict rules had been validated in Christchurch.

"I think the people of Christchurch would pay any price to come through this earthquake unscathed," he said.

earlier related report
New Zealand quake victims remain positive amid destruction
Christchurch, New Zealand (AFP) Sept 5, 2010 - The response among New Zealanders to the most devastating quake in decades has been "tremendous", with an "astonishing atmosphere of resilience" among affected communities, politicians and media said Sunday.

The government said it had turned down international offers of aid after Saturday's 7.0 magnitude quake, as people pulled together to help those left without shelter, food or water.

Civil Defence Minister John Carter said the disaster, which cut a swathe through Christchurch and the Canterbury district, had brought out the best in people.

"It has been tremendous to see the people of Canterbury rally around each other in this disaster and this has certainly reduced demand on the welfare centres," he said.

"It is a great testament to our country that Kiwis can call on family, friends and neighbours, and even in some cases strangers, in times of emergency."

Although the streets were strewn with rubble and shattered glass, and large holes and fissures had appeared in main roads, officials on Sunday said they had the situation under control.

Offers of help from the United States military and from various United Nations programmes were refused, civil defence director John Hamilton said, with the nation of four million able to fend for itself.

"I suppose they're probably surprised that we turned down their offers of assistance because in most cases an earthquake of the magnitude that we've experienced would inevitably result in high casualty numbers and the need for humanitarian assistance," he said.

"We're very grateful that the offers were made and fortunately we were able to say 'not required'."

A state of emergency declared soon after the quake would be reviewed on Monday, officials said.

Saturday's earthquake caused a mess of crumbled buildings, crushed cars and mangled roads which Prime Minister John Key described as looking like parts of the city had been "put in the tumble dryer and been given a darn good shake".

But after the initial shock, New Zealanders quickly set about providing food and accommodation for those who had lost their homes.

With electricity and water supplies cut, neighbourhood barbecues were organised as families pooled food and water supplies.

In rural areas, farmers set up a network of generators to ensure all milking would be completed as quickly as possible.

Opposition leader Phil Goff said he was amazed at the attitude of a couple he met removing possessions from their house, which was only fit for demolition.

"They were saying things like 'well, it could be a lot worse, think of the people in Pakistan where their homes and property have been destroyed, they have nobody to help them out, their kids are suffering from disease'."

Throughout the day the media arrived to collect stories of survival and found "an astonishing atmosphere of resilience", the Sunday Star-Times reported.

"Christchurch took on a carnival atmosphere as strangers compared notes.

"A community rallied and shared its bottled water with its neighbours... even those who had lost almost everything were remarkably upbeat."

Roderick Smith and partner Nina refused to let the earthquake interrupt their wedding day and used the destruction as a backdrop for their wedding photos.

"All the places we were going to do photos were blocked (so) what we've been doing is driving around and finding nice looking rubble and making the most of a bad situation," Nina told the Stuff website.

The chapel where they held the wedding was unscathed but the reception venue was unusable so the party packed into a coffee shop instead.

Nigel Smith spent Saturday using his four-wheel drive to pull stuck cars out of people's driveways.

"Something like this brings people together," he said. "It's amazing how everyone has come out and is helping each other."

Key said it looked like a scene out of a movie: "The roads were just ripped apart. I saw a church completely broken in half."

The earthquake was New Zealand's most destructive since the 1931 tremor in Napier that killed 256 people.