Today's magnitude 5.7 earthquake is a huge setback for the confidence of the city but it has been lucky to escape with no major damage, Mayor Lianne Dalziel says.
Only minor injuries have been reported following the 1.13pm quake, which was 15km east of Christchurch, at a depth of 15km, Geonet reported.
The quake struck just eight days short of the five year anniversary of the 22 February 2011 Christchurch magnitude 6.3 quake, which claimed the lives of 185 people.
Ms Dalziel said people would be feeling vulnerable but that it was a testament to the new infrastructure that there was not more damage.
"It really is a real set-back psychologically for the city," she said.
"It struck very sharply and very unexpectedly. I've kind of got used to hearing an earthquake coming but this came 'bang', without warning."
There have been at least 40 aftershocks ranging from weak to moderate. The largest aftershock was a 4.2 magnitude quake which struck at 6.27pm.
The biggest concern is a cliff collapse at Whitewash Head near Sumner which engineers are assessing to establish its stability. There has also been considerable cliff collapse at Godley Head.
Whitewash Head was already largely out of bounds following the much stronger quake five years ago.
The cordon stopping all but essential travel over the hill close to the cliffs was lifted about 3pm and residents are now left with the job of removing the thin layer of dust that has settled on their homes and vehicles.
Homeowners on Whitewash Head Road said the dust cloud made it impossible to see for more than a few metres in front of them.
Canterbury District Health Board chief executive David Meates said it had had reports of minor injuries and minor damage to Burwood Hospital but people were feeling rattled.
Initial reports indicate there is liquefaction in parts of New Brighton, as well as flooding and power lines being pulled from a house.
Power was cut to about 500 homes mainly in the north-east of Christchurch, with a further 100 without power at Banks Peninsula. But lines company Orion said was not reporting any problems this evening.
Three schools in Christchurch will be closed tomorrow, Christchurch Girls' High School, Aranui High school and St Thomas of Canterbury.
Today's quake was felt from Dunedin to Auckland.
So that was the biggest one we've had for a few years. 1 minor crack in plaster and a mirror fallen. Thanks for the 5yr reminder. #eqnz— James Caygill (@torshin) February 14, 2016
Grabbed the TV to stop it falling, books off, car alarms set off by it in the neighbourhood. #eqnz— Belinda McCammon (@BelMcCammon) February 14, 2016
Christchurch City Council media manager Jocelyn Ritchie was in the supermarket when the quake hit.
"It was just that awful sound again, that rumble. It lasted a good 20 seconds, it was stuff falling of the shelves, people diving under their supermarket trolleys, and everyone just looking at each other going 'no not again'," she said.
Ms Ritchie said people were in tears and trying to contact family and friends but the phone systems appeared to be jammed.
The supermarket cleared everyone out but she had not seen any significant damage, she said.
Civil Defence responds
The National Crisis Management Centre has been stood down following its earlier activation to monitor today's earthquake in Christchurch.
Civil Defence and Emergency Management director Sarah Stuart-Black said it was important people looked after themselves and their families and listened to Radio New Zealand for the latest information.
People also needed to be aware of what to do and prepare for the likely after shocks.
"We would ask that people try to avoid making calls wherever possible, unless it's in an emergency situation, that is that they do need the fire, police or ambulance.
"Sending a short text message to try and minimise the impact on the cellphone network would be really helpful."