Image copyright Getty Images Image caption Christchurch Cathedral was in ruins following the earthquake

Standing behind wire fences, tourists stare at the crippled and neglected grand old lady of this wounded city. The Anglican Cathedral was badly damaged during the magnitude 6.3 earthquake that struck Christchurch in February 2011.

Its famous spire fell in ruins, along with a section of the tower, but while there is fierce disagreement about its future, a short walk away at Latimer Square is a potent symbol of determination and renewal.

The Transitional Cathedral is made mostly of cardboard and was designed by the Japanese architect Shigeru Ban. It opened its doors to worshippers in August 2013 and will be a spiritual headquarters until a permanent replacement is established.

All around a new city is gradually emerging. Although progress for some has been too slow, weighed down by bureaucracy and disagreement, the recovery effort is breeding a renewed sense of self-belief. A vibrant entrepreneurial streak is beginning to flourish.

Some of the businesses that were forced out of central Christchurch after the February 2011 disaster that killed 185 people are returning. Many more will eventually follow.

Image caption Christchurch's innovative cardboard cathedral

At the official opening of the GreenHouse, a new enterprise hub for small IT and digital firms, the BBC met Adam Hutchinson, the founder of GeoZone that provides travel apps for travellers in New Zealand.

"After the earthquake everyone had to learn to adapt. So we were put out of offices, we had to find new places to work, we had to find new projects to work on and it was this chaotic environment that breeds innovation," he said. "I see it as a real innovative city with a lot of interesting people doing really interesting projects."

Redevelopment effort

More than 1,000 buildings in the central business district have been demolished, and the major rebuilding phase is well under way. The cost will exceed NZ$40bn (£17bn; US$27bn), much of it from the insurance industry.

In the immediate aftermath of the 2011 tragedy, powerful aftershocks growled underfoot. Back then, a woman told me it was as if trolls were trying to break through her floorboards.

We could all feel the earth shake, and four years later the ground again rumbles but this time it is the work of pile drivers ramming the sturdiest of foundations into position. It is the industrial drumbeat of redevelopment, and echoes long after sunset.

Image caption John Ombler is overseeing the rebuilding programme in Christchurch

"This year is a year of huge momentum," explains John Ombler, the acting head of the Canterbury Earthquake Recovery Authority, a government-appointed agency that is overseeing the recovery effort in Christchurch.

Strict construction codes should ensure the capital of New Zealand's scenic South Island will have some of the safest buildings in the world.

"At ground level there are foundations that can move with an earthquake," says Mr Ombler.

"There is one large office block here that is on 19 very large ball bearings, so that in case of an earthquake it can move half a metre in any direction depending on the severity of the earthquake and then just gradually settle back into its right place so that buildings can wobble around a little bit."

Image copyright AFP Image caption The old trams are now running again in Cathedral Square

A ride on a heritage tram that now trundles through many of the streets, which were once cordoned off, shows just how far Christchurch has come since the earth shook so violently at lunchtime on a summer's day more than four years ago.

We glide pass condemned office blocks, swathes of vacant land that has been cleared for redevelopment and huge construction sites.

Housing concerns

The herculean task has suffered delays because of more seismic activity, the processing of insurance payouts and red tape.

"There are parts of Christchurch that have absolutely gone full steam ahead, (but) there has been a bit of a slowdown in the central city," says the mayor of Christchurch, Lianne Dalziel.

Image copyright AFP Image caption Inside Christchurch's cardboard cathedral

Despite the hold-ups, the financial health of Christchurch and surrounding agricultural areas has withstood the shock of the earthquake and its aftermath.

"If you looked at the economy you'd never know we'd had a disaster," she says.

"That is because of the strength of the economy of the region. We are a city that serves a very strong rural economy. Our science and technology and manufacturing sector(s) are very high level here. They have proved to be incredibly resilient."

While its central business district is being revived, around 7,000 'quake-hit homes in low-lying eastern districts have also been demolished. Most of the suburb of Bexley has been abandoned, and although many residents have been re-housed, others are still waiting for help.

Media playback is unsupported on your device Media caption Deborah Basckin reports on the building of the cardboard cathedral in 2012

"We've got some serious issues over providing social housing. That is bad stuff. We've still got people living in cars and caravans who shouldn't be," says the Reverend Peter Beck, the former the dean of Christchurch Cathedral.

"I've got a particular concern for elderly folk. Some of the people who have been struggling have died now."

The authorities have said the capital of New Zealand's South Island will have a "functioning" city centre within three years, forcing many companies to wait before returning to its commercial heart.

But the Re: Start Mall, a temporary shopping precinct made of shipping containers, which opened in late 2011 has become, like the cardboard cathedral, a symbol of ingenuity and verve.

Image copyright Getty Images Image caption Four years after the earthquake the city is still under reconstruction

Almost three-quarters of damaged roads, water pipes and sewage systems have been repaired but reconstruction work will almost certainly take more than a decade to complete.

It is a marathon job, but Tom Hooper, the chief executive of the Canterbury Development Corporation, sees a bright future ahead.

"Old Christchurch is gone, new Christchurch will emerge," he says. "It is all about that new Christchurch and how we make it exciting, and vibrant and attractive, and just the coolest little city in the world."