Although there were no reported injuries, parts of the central city were cordoned off as a precaution following one of the most damaging series of quakes since a 7.0 shake in early September caused widespread destruction.

The most powerful of the aftershocks was magnitude 4.9 on the Richter scale and 12 kilometres (7.5 miles) deep with its closeness to the city centre magnifying its impact.

"There have been larger aftershocks but they have tended to be around the city and have damaged usually in-ground infrastructure," said civil defence manager Jon Mitchell.

Christchurch city policy commander Derek Erasmus said there had been some damage to buildings in the inner city.

"As a precaution we have cordoned off two blocks ... until building inspectors have had an opportunity to assess the damage," he said.

About 40,000 houses had their electricity supplies cut for about an hour following the main shake.

Hundreds of shoppers taking advantage of the Boxing Day sales were temporarily evacuated from one of the city's largest malls where there was "superficial" damage, Mitchell said.

del.icio.us	Digg	Reddit
YahooMyWeb	Google	Facebook