New Zealand's Christchurch rocked by earthquakes
The first 5.8 quake struck at 1358 local time (0058 GMT), the US Geological Survey said. A second of similar magnitude hit 80 minutes later.
Dozens of people suffered minor injuries but only 19 were admitted to hospital.
It comes 10 months after swathes of the city were destroyed by another quake.
Friday's first earthquake struck 26km (15 miles) north-east of the city at a depth of 4.7km. The second was in almost exactly the same place, the USGS said.
Buildings were damaged, power supplies cut and the city's airport had to be closed temporarily.
There were rockfalls in some coastal suburbs of the city and the authorities have warned people to stay away from hillside areas.
Power supplies were severed to 26,000 residents but they have now been restored to around 13,000.
Residents have been told to boil their drinking water in case it has been contaminated by sewage.
Witnesses told local media shoppers ran from buildings as goods fell off shelves.
Some shopping centres were evacuated and several supermarkets remain closed on one of the busiest days of the year; Kazinform cites BBC.
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