Cantabrians suffered a swarm of significant aftershocks overnight, the largest a magnitude-5.5 striking shortly before 6am.
The 15km early morning shake took out power in some Christchurch homes and was felt as far afield as Dunedin.
Rattled awake, there was little chance of returning to sleep with a string of smaller shakes rapidly following. The largest, a mag-4.1 struck at 5.54am.
It followed a disrupted night for most in Christchurch.
At 1.27am a magnitude-5.1 quake at 15km deep rocked the city followed a few minutes later by a mag-4.3 at 12km deep.
At 2.20am a mag-3.5 at 20km deep hit, at 5.03am a mag-3.8 hit, just 8km deep.
The aftershocks were predominantly centred offshore, east of Christchurch in Pegasus Bay.
