The U.S. Geological Survey said the quake, at a depth of 2.9 miles, hit the area on New Zealand's South Island at 1:58 p.m. local time. It was centered 16 miles east-northeast of Christchurch and 176 miles south-southwest of Wellington.
Local reports said the quake was followed by aftershocks.
Radio New Zealand quoted police as saying one person was injured in the East Gate Mall and was taken to a hospital. Several malls, busy with Christmas shoppers, were evacuated.
"It's really the last thing we needed -- a shake just before Christmas," a shopper told Radio New Zealand.
Warwick Isaacs of the Canterbury Earthquake Recovery Authority said most of the buildings in central Christchurch were evacuated as a precaution because of concerns about the likelihood of falling rocks. Isaacs had received reports of liquefaction but its extent was not immediately known, the report said.
Liquefaction causes soil to lose its strength and stiffness after being shaken by an earthquake, and can result in extensive damage.
New Zealand Prime Minister John Key in Auckland was being briefed about the situation.
Telephone services were knocked out in some sections of Christchurch. The city's airport terminal was evacuated and authorities closed the runways while they checked for any damage, the radio report said. The airport was expected to reopen later in the day.
Traffic was heavy in the city and drivers were urged to be patient.
Christchurch was ravaged by a 6.3-magnitude earthquake that killed 181 people and destroyed much of the city's downtown area in February.
Stuff.com reported Friday's quake was felt as far south as Queenstown and Lower Hutt in the north. The report said power had been knocked out in some areas in the eastern suburbs of New Brighton and Dallington and Springton in central Canterbury.
Police spokesman Steven Hill said there were no immediate signs of damage in the city However, ambulance services in the city remained busy, attending to a number of calls.
Christchurch Mayor Bob Parker was at Lake Taupo to celebrate Christmas with his family when the quake hit, Stuff.com reported.
"I've been texting family members to see if everyone is OK, everyone is very shaken. I haven't heard any more significant problems at the moment.
"Inevitably it would have caused damage to structures, we hope it hasn't unsettled any rock falls, and we just have to hope the liquefaction issues don't return," he was quoted as saying.
New Zealand is prone to earthquakes as it is located on the so-called Ring of Fire boundary of the Australian and Pacific tectonic plates.