Christchurch hospitals are back up and running and dealing with a "relatively small" number of earthquake-related casualties, said a spokesman.
Apart from two wards at Christchurch Hospital, all Canterbury District Health Board hospitals are operating as normal after yesterday's two large aftershocks and subsequent shakes today.
Main power had been restored to Burwood Hospital yesterday evening, said a CDHB spokesman.
There had been eight admissions over the last 20 hours, and all other cases had been treated or referred and discharged. Of the eight admissions, none were serious, six were fractures and two were burns.
He said while structural engineers had reported some new damage to buildings, "there is none that people should be concerned about."
Structural engineers are continuing to inspect all CDHB buildings after each significant aftershock.
He said no boil water notices had been issued for Christchurch and surrounds, and all 24-hour services were operating as normal.
Christchurch City Council had reported some sewage discharge to the Heathcote estuary, and members of the public were advised to avoid contact with the water in the area for the 48 hours following the last significant aftershock.
Aftershocks cut water supply
Overnight aftershocks had cut the water supply to Sumner in Christchurch.
Civil Defence controller Michael Aitken says a 4.2 magnitude shake early this morning ruptured the main.
"The shake at about 1:21am this morning caused a bigger rupture and that had already been leaking, and in order to access that to fix it we've had to turn off the water supply to Sumner.''
Aftershocks continue to hit Canterbury
There have been 23 aftershocks since midnight, including a 5.1 which struck at 6.37 this morning.
In Diamond Harbour, Gary Henderson says that particular shake seemed to go on, and on.
"It started out very violent, I had stuff thrown off all the shelves in my lounge and as it eased off it got lesser and less, and I'm shaking like diva.''
Mr Henderson says like all Cantabrians, he's over it.
Christmas cheer returns for retailers
Meanwhile it appears many in the city have chosen to get back on with the business of Christmas.
The news from Christchurch retailers is mixed, on what should be one of the best shopping days of the year.
Central City Business Association manager Paul Lonsdale says the ReStart area and Ballantynes in City Mall are open today.
"We've had all our assessments done and we're good to go so we'll be open at 9am this morning.''
But the Palms shopping centre in Shirley will be closed today.
Centre manager Keryn Ward says they're not ready for customers yet.
"Structurally the building has performed extremely well so the engineers are really pleased, but there's a few bits and pieces we need to fix up and there's a lot to clear up I'm afraid.''
People who need to collect cars from the mall carpark will be able to do so from 9:30am.
A decision on Boxing Day shopping is yet to be made.
Northlands Mall and Riccarton Mall will reopen today.
Several supermarkets in the city however are still closed this morning.
The Countdown stores at Bush Inn, Eastgate, Moorhouse Avenue, New Brighton, Northlands, Northwood and The Palms are all out of action.
Almost all the Pak n Save stores are open - New World at Kaiapoi will be trading from 10am, Stanmore New World will be up and running by mid-morning, and Wainoni Pak n Save should open at midday.
Foodstuffs is asking people to shop normally and not panic buy.
Clean up continues
Quake-weary residents in Christchurch's eastern suburbs were again flooded with silt from liquefaction just two days from Christmas.
Flooding covered streets and homes in suburbs already devastated by the September and February earthquakes, including Bexley, Avonside, Parklands and Wainoni.
Civil Defence said the situation in the city was similar to the magnitude 6 quake in June in terms of damage and liquefaction. St John treated about 60 people with earthquake-related injuries.
Christchurch Deputy Mayor Ngaire Button, speaking while mayor Bob Parker made his way back from a holiday in Taupo, said the timing was almost as bad as the damage.
"Our hearts go out to the people of Christchurch tonight. We're just devastated that this has happened at this time of the year, right before Christmas.
"Most of the council staff had left the building, and we were driving home, we'd all said goodbye, and within an hour we were all saying hello again."
Canterbury Earthquake Recovery Authority head Roger Sutton took in the damage from a helicopter fly-over shortly after the earthquakes.
He said liquefaction seemed similar in some areas to September.
The worst hit areas were those previously red-zoned, such as around Bexley.
"Some areas appear worse, some don't appear quite so badly. But it's not as bad in general compared to February," he said. "But there will be a lot of people in the east tonight feeling very, very frustrated."
Lights go back on
About 26,000 properties - most in the east - lost power following the earthquakes. Fewer than 400 were still in the dark last night.
Orion Power chief executive Rob Jamieson said he was hopeful the outages were not due to major damage to the network and that power could be restored quickly.
The shaking brought down a stopbank and a red-stickered house near New Brighton in the city's east, a partly-demolished building in the Central City and a vacant house in Hillsborough.
A plume of dust was seen rising from the central city following the first earthquake and Mr Sutton said Christchurch Cathedral had suffered further damage.
"But we haven't seen any of the really big buildings that we were concerned about, none of them have sustained damage, which is great."
The Red Zone is likely to remain closed for several days, which will allow engineers to concentrate on checking residential and commercial properties.
Four people had to be rescued by the Coastguard after being trapped by a rockfall in Boulder Bay, and people were told to stay away from hill suburbs after rockfalls in Scarborough and Redcliffs.
Part of a house perched on the edge of the Scarborough rockface had fallen onto the rocks below, hemmed in by containers.
Ms Button said while many of the properties around the rockfall areas were abandoned, teams would check on all homes in the area.
Major potholes appeared on Broadhaven Ave near Waimairi Beach and traffic lights were out in the eastern suburbs.
Other roads became congested as residents attempted to return home to check on their family and property.
There were no sewage overflows but sewers were damaged as were stopbanks along the Avon River, which authorities hoped would hold over this morning's 4am high tide.
Christchurch Airport was evacuated but flights resumed around 6pm after runways and the terminal buildings were cleared of damage.