Latest updates: More aftershocks to come - GNS

File photo / NZ Herald

10 biggest aftershocks to hit Christchurch

He had received early reports of buildings buckling in the city centre and was still waiting to hear whether there were injuries to staff working in the area.

The council building had been evacuated, he said.

"I must admit I was very concerned. Our building was rattling and shaking. Trees in the streets were waving at crazy angles."

The quake would have brought back traumatic memories for many residents, Mr Parker said.

"It doesn't even take a 5.5 magnitude to bring back traumatic memories. Any quake brings it all back. All your can do is wait. That's all. You can't move."

Residents have taken to Twitter to post about the quake, with many describing it as powerful and estimating it at a near 6 magnitude.

Lilmagoolie said her house "wobbled like crazy" - with the shaking almost as bad as the February shock.

"Big quake. House still moving. Alarms going off everywhere."

Mattdeevee said: "oh my gosh that was so scary!!!!!! Biggest since Feb by far 5.9?!"

Nathanael Boehm, NathanaelB, said he was ready to jump out a

"Was up and ready to leap out a window if it started coming down!"