Five years, 14,000 quakes, and a new South Island

Each dot represents an earthquake recorded by GeoNet.
Geonet

Each dot represents an earthquake recorded by GeoNet.

Each dot represents an earthquake recorded by GeoNet. Zoom in or out to see exactly where they happened.

When a quiet fault line roared to life near Darfield more than five years ago, it triggered a series of events that would fundamentally alter the South Island's course.

The first earthquake, on September 4, 2010, struck like a lightning bolt. In its wake have come at least 14,000 confirmed aftershocks - Geonet has recorded almost 18,000 seismic events - which have knocked the region further off its axis.

On February 22, 2011, with the 600 earthquakes recorded that day, the change was apparent - 185 dead, buildings destroyed and lives wrecked.

What was less evident were the broader, structural changes, only just becoming apparent now.

The 14,000 earthquakes introduced a Canterbury no one expected to ever see, far different from the one that was supposed to be.

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A significant population shift came with the earthquakes, which has fundamentally changed the entire South Island.

One way to examine the magnitude of this is to compare Canterbury now to what it was projected to look like prior to the quake.

Every few years, Statistics NZ projects future populations based on contemporary trends.

In 2006, based on census data, it projected what Canterbury could have looked like in a decade.

It shows that if the earthquakes had never happened, Christchurch City would be on the cusp of a milestone. Its population was projected to increase by 14,000 between 2011 and 2016 one for every aftershock - bringing it just shy of 400,000.

But during the worst of the earthquakes, 16,600 people left the city. Some didn't come back.

Latest projections estimate the city will surpass 400,000 people by 2028: about a decade behind schedule.

In five years, the city's population has increased by just 100, a fraction of the 14,000 projected. It wasn't until last year that the city's population finally returned to pre-quake levels.

Looking wider, it's easy to see where many of those 13,900 went. The lurch towards the north and the west has been momentous.

Over five years, Statistics NZ projected a population increase of 3000 - about 9 per cent - in Selwyn District.

It more than quadrupled that projection. Its population has increased by 14,000, about 28 per cent, which has made it the fastest growing district nationally several years in a row.

Similarly, Waimakariri increased its population by 8400 (16 per cent), and Ashburton by 5200 (10 per cent), both well above projected growth.

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The red districts have had the biggest growth; blue, the lowest. Hover to see how each district has changed.

As you get closer to Christchurch, the make-up of the population changes noticeably.

Broadly speaking, Canterbury as a whole has become younger and more masculine. The rest of the South Island, however, is the opposite: it has become older and more feminine.

In Kaikoura, Marlborough and Tasman, the median age has increased by several years, and the ratio of women has increased

In Canterbury, all territories except Hurunui have more men and a younger median age than in 2011. It is particularly evident in Christchurch and surrounding territories, where the construction trade is booming.

The number of construction jobs rose by 106 per cent in five years; the industry with the next highest increase was arts and recreation, with 23 per cent.

There are 49,000 construction jobs in Canterbury, more than double the number recorded in 2010, according to the household labour force survey.

About 41,000 of those jobs are held by men. Beyond the demographic impact, the influx of men correlates with other effects - for example, a small widening of the wage gap, where in five years women's wages have increased by $3.20 an hour, and men's by $4 an hour.

Men mostly went to the city. While Christchurch gained 5800 men, it lost 300 women. Virtually all of this change occurred in the 15-39 year old age group.

The result is a significant shift in the city's sex ratio. In 2015, Christchurch's male to female ratio was exactly the same, with 183,900 of each.

Christchurch is now the only New Zealand city where women don't outnumber men.

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In May 2013, The Press marked the 1000 day anniversary of the February 22 quakes with a progress dashboard. It showed how far the rebuild had come in key areas.

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Most measures were between a third and halfway done. Updated numbers show the bulk of the work has almost finished.  

The majority of home repairs - about 68,000 - have been completed, although more than 4500 homeowners are yet to settle with their insurer. 

Each dot represents an earthquake recorded by GeoNet.
DEAN KOZANIC

Each dot represents an earthquake recorded by GeoNet.

About 650,000 metres of pipe has been laid, which if you laid end to end would reach from Christchurch to Blenheim and back again. About 1.3million square metres of road has been repaired.

The insurance history has paid out $16.7b in claims. EQC has paid out $9b.

At its peak, building consents were up 306 per cent, triple the national rate. Almost 11,000 building consents have been quake-related, to a value of $3.42b.

Still, there is more to do. Around 3000 building claims are unresolved, as are 19,200 land claims.

Thousands of homes will need to be re-visited due to issues with the original repair.

About 30 of the 7,000 Crown-owned red-zoned homes on flat land still need to be demolished, as do about 250 in the Port Hills red-zone.

It will add to the 700,000 tonnes of mangled buildings which have already been processed in Burwood, and contribute to the 40 years worth of waste the earthquakes have produced.

The Stronger Christchurch Infrastructure Rebuild Team (Scirt), which is leading repairs of the city's infrastructure, said it was heartened by the progress being made.

"The repairing of Christchurch's infrastructure's been a huge and a gratifying challenge," said executive general manager Ian Campbell.

"It was particularly satisfying to be able to quickly complete our work in the CBD, to largely enable the vertical rebuild. Scirt's programme focus is now on finishing projects in the suburbs of Christchurch."

Much of its work had been focussed on the eastern suburbs, where the damage was worst, he said.

It would now move towards smaller jobs in the western suburbs, and hoped to complete its earthquake repair programme by the end of the year.

Major projects ahead included repairing two large wastewater trunk pipes, roading works in several suburbs, and repair of several city overbridges.

 - Stuff

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