A shallow aftershock rattled the New Zealand city of Christchurch on Tuesday, cutting power, forcing evacuations and sending items crashing from shelves, officials and witnesses said.

The 4.7-magnitude quake hit at 11:32am (2232 Monday GMT) and was centred 12 kilometres (8 miles) southwest of Christchurch at a depth of just 9.0 kilometres, the US Geologial Survey said.

It was among the strongest of almost 2,000 aftershocks that have hit New Zealand's second largest city since a 7.0-magnitude tremor on September 4 caused widespread destruction.

GNS Science duty seismologist Sara Page said the latest quake was closer to the city than previous aftershocks, magnifying its impact.

"That would be the biggest, closest one we've had for a while," she told the Christchurch Press.

Christchurch airport said flights were temporarily suspended while runways were inspected for damage, while electricity supplier Orion said 10,000 homes lost power for about 20 minutes.

Police said a shopping mall at Riccarton, west of the city centre, was evacuated as a precaution. Workers at numerous buildings in the central business district also fled their offices, local media reported.

Shop owner Fiona Fidow said the power of the shaking sent crockery crashing from her shelves.

"This was very loud, very strong shaking," she told Fairfax Media's stuff.co.nz website.

"All our china is smashed in our kiosk. The mall alarms are going off and the mall has been evacuated. Quite a few people are crying and hysterical. There are a lot of frightened people."

Christchurch Hospital, which switched briefly to back-up generator power after the tremor, said it had received no reports of injuries.

Cafe operator Flick Holmes said the shaking lasted about 20 seconds, jarring the nerves of residents already on edge from the constant rumblings that have followed last month's quake.

"It definitely was a very big one, everything rocked," she told national news agency NZPA> "Just when you think you're getting used to it (another) goes."

GNS Science said more large aftershocks could be expected in the region until seismic activity settled down following the September 4 quake, which was the most destructive to hit New Zealand in 80 years.

It did not result in any deaths but damaged 100,000 homes and left a clean-up bill estimated at four billion dollars (three billion US).