Aftershocks continued to rattle the earthquake-shattered New Zealand city of Christchurch Saturday overshadowing Christmas preparations for weary residents in a "hellish year".

File photo shows the quake-damaged Christchurch Cathedral on September 7.

Emergency services were rushing to restore electricity and water supplies and an army of 2,000 volunteers were helping clean up the worst affected suburbs by Christmas Day.

"There is a real determination in our city not to let the events of the past 24 hours ruin Christmas. Our crews have worked overnight and will be working all today to restore services to the city," Christchurch Mayor Bob Parker said.

"Our goal is that by the end of the day we will have made the necessary emergency repairs to our water, wastewater and roads.

"It has been a hellish year. I am determined to get as much as we can fixed by tonight so that our staff, apart from a skeleton team, can spend Christmas with their families."

The latest flurry of earthquakes began at 1:58pm (0058 GMT) on Friday, sending Christmas shoppers fleeing from stores in panic as stock fell from shelves and forcing the closure of the international airport as a precaution.

Over the following 24 hours there were 39 earthquakes of magnitude 3.0 or stronger including four over 5.0.

At least three houses that had been in a precarious state following powerful shakes earlier in the year collapsed and one large shopping mall was unable to open Christmas Eve, one of the most lucrative days of the year.

Prime Minister John Key toured the city Saturday and said he did not believe the latest quakes would have a dramatic impact on the already significant repair bill.

"What we can conclude is that the most significant damage from the earthquakes is really the psychological damage and the impact on the confidence of the people of the Christchurch," he said.

"This is quite a blow to the people of Canterbury (region), but I want them to know that the country is 100 percent behind them, that our resolution to see Christchurch rebuilt has not diminished in any way as a result of the aftershocks."

The repair bill from the ongoing earthquakes which began with a 7.0 magnitude shock 15 months ago, has already reached NZ$20 billion (US$15.5 billion).

As tension mounted in the city and a special help-line was set up for people feeling distressed, civil defence warned the aftershocks would continue for some time.

"Unfortunately when there is a large earthquake of this kind, people do need to expect aftershocks," civil defence spokesman Vince Cholewa said.

It was too much for Sarah and Judah Matenga, who said they planned to move to Australia after seeing their property once again covered in liquefaction, a sludge pushed up through the earth by the force of the earthquake.

"That's the plan, move to Oz," Matenga told the New Zealand Herald. "This is the last straw, really. Christmas still has to go ahead, but after that we'll be out of here."

His neighbour Sarno Yambasef said the initial shake seemed to lift his house off its piles.

"Everything was really rocking. It was a pretty violent shake, and now look at it. The liquefaction is just too much to deal with. The smell of sewage is awful. It reeks in the hall and bedroom. The walls are cracked."

Parker described the quakes as a "hammer blow" for Christchurch but believed most residents would remain resilient, Fairfax News reported.

"I think we will bounce back pretty quickly. For some people this will be a last straw, but I think the vast majority have shown they're here to stay."

New Zealand sits on the so-called "Ring of Fire" the boundary of the Australian and Pacific tectonic plates, and experiences up to 15,000 tremors a year.