Part of central Christchurch is cordoned-off again after a series of aftershocks on Boxing Day.
Inspector Derek Erasmus says the quakes have caused some damage to buildings in the inner city.
As a precaution, two blocks bounded by Oxford Terrace, Lichfield Street, Hereford Street and Colombo Street are cordoned off until building inspectors have an opportunity to assess the damage.
Acting Mayor Ngaire Button says she hopes the cordon will be in place for days, not weeks.
Inspector Erasmus says he understands suburban Christchurch has not been badly affected by the latest quakes.
The strongest was magnitude 4.9 at 10.30am, at a depth of 12km.
It was the fifth quake since a magnitude 4.2 occurred at 2.07am.
Power was off for an hour in the Christchurch central business district and Fendalton. Lines company Orion says 40,000 customers were affected.
Chief executive Roger Sutton says power was restored to all areas within an hour.
He says all equipment has worked as it should, but the shocks were close to transformers, and set off protective alarms inside.
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.