Christchurch struck by 4.8 quake

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A 4.8 magnitude earthquake has rattled Christchurch.

Geonet said the shock hit at a depth of 11 kilometres, about 20 kilometres southeast of Darfield, just before 3:30pm.

St John has had no reports of injuries following this afternoon's earthquake.

Its epicentre was near the town of Rolleston.

A Geonet seismologist said early calculations put the quake at 5.0, but those had since been downgraded.

The quake was followed by a magnitude 3.1 aftershock at a depth of eight kilometres about 25 km west of Christchurch at 3:41pm.

Christchurch residents took to Twitter to report the latest shock, with some describing it as "huge".

EmmaJayJenkins said: "Crazy earthquake made my car start bouncing around while we were waiting at the lights!"

RepsTweets said: "I'm still shaking, that was huge."

Newstalk ZB reporter Brian Ashby said it felt like a long, rolling one.

"I heard it coming, I was wondering if it was traffic, a big truck. All of a sudden then it hit, and it rolled. It probably lasted about 20 seconds.''

A magnitude 4 quake hit the city last Friday.