Christchurch was rattled by another strong aftershock on Thursday night.
The country's second-biggest city continues to experience tremors following a powerful 6.3-magnitude earthquake which caused severe damage on 22 February.
Witnesses say the tremor at 8.07pm lasted for seven to eight seconds and was a sharp jolt, stronger than most other aftershocks experienced to date.
GNS Science says the 4.5-magnitude aftershock was was centred 10km east of Christchurch at a depth of 10km.
It followed an earlier aftershock at 7.25pm, which measured 3.2.
Another quake of magnitude 3.2 was felt at 9.24pm.