Christchurch residents were shaken awake by a strong magnitude 4.2 earthquake this morning.
GeoNet said the 9km-deep quake struck 20km west of Christchurch at 4.21am.
Some residents were woken by the quake, with Nicola Stratton saying on Twitter: "Wide awake, heart pounding after an earthquake to start the day."
Anthea Livingstone tweeted: "Reminiscent of old times. We're awake in the middle of the night."
The GeoNet website had received almost 500 reports from people who felt the quake this morning.
