The Canterbury region has recorded its largest aftershock in 36 hours.
The tremor was of magnitude 4.3 at 9.12am on Tuesday. It was centred 20km south east of Darfield, at a depth of 9km.
It was followed at 9.27am by a 3.4 quake at a depth of 8km.
Eight earthquakes have occurred since midnight. One of these was magnitude 3.9 at 5.38am.