The New Zealand Treasury has upgraded the cost of the Canterbury earthquakes from $NZ15 billion ($11.5 billion) to $NZ20 billion ($15 billion).

Treasury says the reconstruction work will gather momentum over 2012 and into 2013, generating higher employment and business investment and helping insulate the economy from the impact of slowing growth in the economies of New Zealand’s trading partners.

The updated cost is contained in its Pre-election Economic and Fiscal Update, produced prior to the national election on November 26.

The Earthquake Commission (EQC) has set up a website with daily and weekly updates of claims it has received and paid, and says it is paying around $NZ7.5 million ($5.7 million) a week in contents claims.

It has paid $NZ1.06 billion ($810 million) for the first earthquake on September 4 2010 and $NZ1.03 billion ($790 million) from the February 22 earthquake, which killed 181 people.

Last year’s Boxing Day quake caused payments of $NZ12 million ($9 million) and the June 13 event $NZ31 million ($23.7 million).

All events, including aftershocks, have cost the EQC $NZ2.16 billion ($1.6 billion) from 405,000 claims so far.

Rebuilding work continues, with part of Christchurch’s central business district re-opening at the weekend with a shopping area built from shipping containers housing 27 temporary shops.

Canterbury Earthquake Recovery Authority CEO Roger Sutton says the new shopping area “is another sign that while we are still dealing with the aftermath of the earthquakes, we are moving forward and starting to rebuild”.

Christchurch’s tallest building, the 21-storey PricewaterhouseCoopers Building, will be demolished, with the lead insurer Vero and the building’s owner, Kiwi Income Property Trust, agreeing that it cannot be economically repaired.

The tower was completed in 1990 and its value prior to the earthquakes was $NZ52.2 million ($40 million).

Homeowners are also starting to rebuild, with Earthquake Recovery Minister Gerry Brownlee announcing that more than 6000 properties have been rezoned from orange to green, meaning that work to remediate the land and repair homes can begin.

More than 180,000 properties have now been zoned green and the Department of Building and Housing has developed three new technical categories for residential foundation design as part of its guidance for repairing and rebuilding earthquake-damaged homes in Canterbury.

Mr Brownlee says another 1666 residential properties remain in the orange zone because further work is required before decisions can be made about the land they are on.

The Government has made an offer to buy back the homes and land of people in red zones.