Christchurch was hit by a sharp 5.2 magnitude earthquake on Friday, but there are no reports of injury or damage.
Geonet says the earthquake struck at 2.44pm and was centred 10km east of the South Island city at a depth of 11km.
An aftershock measuring 3.1 was felt at 4.02pm in the same area and depth.
The Canterbury Earthquake Recovery Authority says it has cleared the central city red zone of workers for the day, but nothing fell down and no one in the area was hurt.
No new liquefaction has been reported, while St John Ambulance and police say they have had no calls about injuries or damage in the city.
Lines company Orion says power has not been disrupted.
The New Brighton Library has been declared safe after being briefly evacuated while it was checked for damage.
However, the temporary Linwood Library has been closed for the day and people were also kept out of the Lyttelton Library.
The tremor was felt as far south as Timaru and Dunedin.
One Christchurch resident tweeted there are no words that adequately explain just how damaging to sanity these quakes are.