Forty-nine buildings have been added to the demolition list in Christchurch taking the total to nearly 500.
Many buildings were badly damaged after a 6.3-magnitude earthquake hit the city on 22 February.
The Canterbury Earthquake Recovery Authority says hundreds more will be added in coming months and expects to finalise the number by the end of September.
The authority's demolitions manager, Warwick Isaacs, says it has sent out 10-day notices to property owners warning them that if they do not provide a demolition plan, it will do it on their behalf.
Mr Isaacs expects the rate of demolition in Christchurch to increase over the next few weeks.
Demolition work is beginning in the Cashel Mall area this week, where 24 buildings are earmarked for partial or full demolition.
Mr Isaacs says demolition teams will then move to Hereford, Lichfield, Tuam and St Asaph streets.