Police in Christchurch say a series of tremors felt in the city on Boxing Day had a big impact because of their shallow depth and closeness to the CBD.
The strongest was magnitude 4.9 at 10.30am, at a depth of 12km.
Power was cut to around 40,000 premises, but Orion says services were restored to all of them within an hour.
Road closures in Oxford Terrace and Colombo Street were lifted on Sunday afternoon.
However, Christchurch City Council says a cordon remains in place in Lichfield Street, Hereford Street, City Mall and Gloucester Street between Manchester and Latimer Square.
The council says this cordon is in place to protect public safety while assessments are carried out on buildings damaged during the latest earthquakes.
While there has been no evacuations, the council says no one is being allowed to re-enter the cordoned area while the assessments are underway.
Inspector Derek Erasmus says public safety is paramount.
Acting Mayor Ngaire Button says she hopes the cordon will be in place for days, not weeks.
Twenty buildings are known to have been damaged.
Structural assessments are being undertaken by 10 Civil Defence teams.
The council says most of the damage has occurred in buildings already affected by the first earthquake on 4 September, which was magnitude 7.1.
Emergency services will also check other buildings in the area for damage.
Once Civil Defence staff have completed the assessments, individual building owners will work through the remediation process with their insurers.
Building owners who return after the holidays and discover damage should consult their own engineers and insurers.
Civil Defence has set up an emergency operations centre at the council's Hereford Street building and emergency services are assessing the situation across the city.
Damage has largely been limited to the central city. No major damage reported in the suburbs.
No injuries reported
Civil Defence has received no reports of injuries as a result of the quakes.
The council says water, wastewater and stormwater networks were not damaged.
Power has been restored across the city and the traffic light network is operating with some intermittent faults.
A magnitude 7.1 earthquake occurred in Canterbury at 4.35am on 4 September.
A state of emergency was declared and the central business district in Christchurch was cordoned-off for several days. Aftershocks have been occurring ever since.
The state of emergency was in force until 16 September.