The Prime Minister says the Government has a clear picture of what areas of Christchurch cannot be rebuilt on due to earthquake damage, but will not reveal them yet.
John Key says as well as damaging buildings, it appears the 5.6 and 6.3-magnitude quakes on Monday have further damaged land already marginal following the devastating quake on 22 February in which 181 people were killed.
Mr Key visited Christchurch on Tuesday and says decisions could be made soon about which parts of the city will be abandoned.
However, he says engineers need to be consulted further and negotiations have to be concluded with the Earthquake Commission, insurers and re-insurers.
Mr Key told Checkpoint he thinks most residents will have an idea of whether their land can be rebuilt on or not, and he wants to maximise the return to homeowners if they have suffered any damage.
The Government cannot give a timeframe on when homeowners will be contacted, as it wants to ensure there is clarity for those who have to abandon their land and those who can rebuild, he says.
The Canterbury Earthquake Recovery Authority says about 100 more buildings will have to be demolished urgently after Monday's tremors.