Canterbury has been rocked by another strong aftershock.
The 5.3 magnitude tremor struck at 10.34pm and was centred 10km west of Akaroa at a depth of 12km, GNS Science reported.
It was felt throughout Canterbury.
Power was thought to have been cut to some suburbs including IIam, Avonhead and Burnside but police said there had been no reports of serious problems following the tremor.
"This was never a 5.3!, wait for the upgrade," One woman said on the Christchurch Quake Live Facebook page.
"I had just finished work hopped in my car and just as I went to shut the door the car rocked so violently I couldn't get out, when I did the pine trees above me were swaying from side to side."
Several people on social networking sites said the aftershock appeared to go "on and on".
Police and the Fire Service reported no initial damage.
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