A swarm of aftershocks rattled Christchurch again overnight knocking out power to a some parts of two western suburbs but no major damage is reported.
A number of aftershocks struck the already quake-battered region, including a 5.3 magnitude tremor at 10.34pm.
The quake, centred 10km west of Akaroa at a depth of 12km, was the largest to hit the region since magnitude 5.7 and 6.3 quakes last Monday.
It was followed by nine more aftershocks of magnitude 3.1 or greater centred around the city, Lyttelton and Akaroa until about 5.15am.
The largest jolt briefly cut power last night to some western suburbs including Ilam and Avonhead but police said there had been no serious problems following the tremor.
Police took just two calls from people feeling unsafe.
"People are getting quite used to them now, they know what to do," a southern police communications spokeswoman said.
Christchurch Airport was reportedly closed for a short time while staff checked the runways.
