The Christchurch red zone has reopened after a 5.1 aftershock in Canterbury this morning.
Indicator buildings in the Christchurch central city were inspected after the large aftershock, which struck at 5.39am, near Dunsandal, 20km northwest of Leeston, at a depth of 12km.
A CERA spokeswoman said there were no intial reports of damage.
She did not expect to see any urgent demolitions like those ordered in the aftermath of 5.6 and 6.3 magnitude aftershocks in June.
GNS Science said this morning's quake was felt across Canterbury, receiving reports it was felt as far north as Cheviot, as far south as Kaitangata, and also on the West Coast.
Orion said there had been no power outages as a result of the jolt.
Cantabrians turned to social networking site Twitter to share their experience.
"Another aftershock to wake us up. 5.1mag @ 5.39am. Who needs an alarm clock," Michelle Joy wrote.
"Arrrh the familiar sound of breaking glass at 5.42am," Adrienne Rewi tweeted.
Jo Gilbert said "this am's shake was a gentle, rolling reminder that THAT is still hanging around. I hadn't felt anything more than a wee wobble in ages."
