Christchurch's red zone has been shut down following a significant aftershock.
Geonet said the the magnitude 5.2 earthquake, centred 10km east of Christchurch and 11km underground, struck at 2.44pm.
It was followed four minutes later by a magnitude 3.6 quake, at a depth of 20km and centred 5km north east of Christchurch.
Geonet labelled the intensity of the first quake as "damaging". But Christchurch City Council said there were no reports of damage and St John Ambulance received no reports of injuries.
A spokeswoman for the Canterbury Earthquake Recovery Authority said the red zone had been shut down as a precaution.
There had been no "significant damage" to the redzone but some loose bricks and tiles had fallen off the Christ Church Cathedral.
"Nothing was made worse than it already was."
Workers were told to go home as a "precautionary measure".
"It was already 3pm and we thought it would be best, since it was a [magnitude] 5, to send everyone home and make sure they felt safe. There were no injuries reported."
Lyttelton Library has also been evacuated.
The quake was felt strongly across Christchurch, with Twitter users saying shoppers ran from the Eastgate Mall.
Cheryl Bernstein Tweeted that she heard a "big loud banging" and things fell off her shelves.
Another Twitter user said the earthquake lasted for more than 10 seconds and it caused the building they were in to rock back and forth.
It's months since Christchurch has had a quake registering above magnitude 5. On January 15, a magnitude 5.1 quakestruck off the New Brighton coast.
Today's shake was the 41st quake greater than magnitude 5 since the destructive September 4, 2010, earthquake.
- © Fairfax NZ News
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