The Society for Earthquake Engineering says the time it could take before some multi-storey buildings in Christchurch are repaired could keep parts of the city shut down for years.
The society says it could take five years for a multi-story building to be repaired, depending on the damage.
Executive officer Win Clark says some owners are already under pressure from surrounding businesses to demolish their buildings, rather than repair them, so neighbouring firms can reopen faster.
Mr Clark says many such businesses want to reopen, but it is not safe for them to do so until the multi-storey buildings nearby are stablised or demolished.
In some cases, he says, it will be cheaper and faster to choose demolition.