A strong earthquake struck about 4.30am near northern Canterbury. Image: Google
The 5.1 magnitude quake hit just before 4.30am, about 10km north-west of Culverden.
GeoNet, who initially said it was a 4.9 magnitude event, said it happened at a depth of 10km.
An alert on Twitter said the quake was causing strong shaking near Culverden at 4.30am.
Hundreds of people have reported feeling it - including those in Christchurch.
Just before 6.30am, 679 people had checked in on GeoNet's "felt report" page; with three people reporting it felt "extreme" where they were.
There are no reports of damage at this stage.
