Quake - one year on: What if it happened in Auckland?

Imagine downtown Auckland culled of half of its buildings, and only a smattering of high rises peeking above the rubble. Or suburban Auckland with bare, uninhabitable patches eight times larger than the Domain.

That's what Christchurch is struggling with after a year of earthquakes - the potential loss of 600ha of residential land, 900 commercial buildings in its city centre, and huge sections of its heritage quarters.

To illustrate that destruction to North Island readers, the Herald translated those losses to Auckland's infrastructure in this artist's impression - overlaying the Christchurch red zone onto the CBD of Auckland and imagining the same approximate level of damage.

The Christchurch Earthquake Recovery Authority has partially or completely demolished 600 buildings, out of an expected total of 1200.

Nine hundred of these demolitions will take place in the CBD. In the 71ha central-city red zone, half of the buildings will be levelled.

Applied to Auckland's central city, that amount of destruction would be similar to knocking down every building from the waterfront up to Victoria St. The red zone's borders would be Nelson St, Quay St, Albert Park and Cook St/Mayoral Drive.

In Christchurch's wider CBD - bordered by Moorhouse, Bealey, Fitzgerald and Deans Avenues, a third of the buildings will be partly or totally pulled down, leaving a much lowered cityscape with around 10 or 15 high-rise towers.

Fresh construction in Christchurch, including shops made out of shipping containers, has begun to fill the holes - but big gaps in the city's business district remain.

The city's architectural heritage will be undermined by the demolition of 100 protected buildings - five of them listed as "significant" - and authorities still have to decide whether to repair or demolish the town hall.

The head of the demolition project, Warwick Isaacs, says residents could be "shocked" by the estimates that 600ha of residential land has been severely damaged by liquefaction - around four times the size of Hagley Park.

Earthquake recovery officials have indicated that this land will be useless for years.

In Auckland terms, that amount of land is more than four times the size of Ponsonby or twice the size of Mt Eden.

The Auckland Domain, at 74ha, is a fraction of the Christchurch land drowned in mucky silt. Around 1.2 per cent of Christchurch's suburban and central city land is severely affected by liquefaction.

If the Auckland region had the same proportion of damaged land, 5000ha would be written off - a space more than half the size of Waiheke Island.