The Government has declared a national state of emergency after yesterday's 6.3 magnitude earthquake in Christchurch.

At least 75 people have been confirmed dead in the earthquake, with the toll expected to rise significantly as more bodies are found and identified. The earthquake has devastated the centre of Christchurch, destroying buildings and infrastructure in the city.

Prime Minister John Key said a national emergency would allow the greatest possible coordination of local, national, and international resources to work on rescue and recovery efforts.

Civil Defence director John Hamilton will able to exercise control over the functions, duties, and powers of Civil Defence emergency management groups throughout the country.

Those powers would be exercised working in close support of and cooperation with Christchurch Mayor Bob Parker, and the Christchurch Civil Defence team.

Civil Defence minister John Carter will make a statement to Parliament this afternoon.

Mr Key said he would be telling Earthquake Recovery Minister Gerry Brownlee to solely focus on Christchurch, and pass on his other ministerial responsibilities to other ministers.

Mr Key said the quake had brought "death and destruction on a dreadful scale".

He said there was no question the earthquake would have a significant economic impact on Christchurch and New Zealand, given the damage to the city's CBD.

The central city was likely to be out of action for some time.

"We're going to have to go back and reassess every building."

Mr Key said the first earthquake was estimated to have cost between $6bn and $8bn. Initial advice suggested the bill for yesterday's quake would be far more costly.

"We can afford that," said Mr Key but he said it would put a dent in the EQC's and the Government's resources.

Following this morning's media briefing, Mr Key planned to immediately head back to Christchurch.

What a national state of emergency entails

Declaring a national state of emergency is an option when a disaster or other event is or is likely to be of such severity that it is beyond the resources of the local Civil Defence groups.

It provides for a national resources to be marshalled to perform emergency functions and tasks such as:

* rescues
* evacuations from dangerous areas and the closing off of buildings, homes and other premises, public places and roads.
*setting up first aid posts
*providing relief such as emergency food, clothing and shelter
*regulating road, air and sea traffic
*undertaking the emergency disposal of bodies

It also allows authorities to requisition any land, building, vehicle, animal, boat, equipment, construction materials, bedding, food and medical supplies considered necessary for the preservation of human life.

New Zealand flags are flying at half mast on all Government buildings today to honour the victims of yesterday's devastating quake in Christchurch.

Mr Key requested the flags on all public buildings be half-masted indefinitely.

The gesture is intended as a mark of respect for those who have been killed, injured or left with damaged homes.


Civil Defence said welfare centres had been busy overnight, as had hospitals and medical facilities.

About 950 people spent the night at two welfare centres, at Hagley Park and Burnside High School, where blankets, food, sanitation were supplied.

Social Development Minister Paula Bennett said more welfare centres would be opened once buildings were declare safe to use.

"The advice is to stay at home if people can and to check on their neighbours and if they need any help or advice, call the Government helpline," she said.

The 0800 779997 helpline will operate 24 hours, providing information, advice and transferring calls through to other appropriate agencies.

"Financial assistance will also be made available to those who need it, we have the ability to provide Civil Defence emergency payments and other assistance is available," Ms Bennett said.

Telecommunications were patchy and many residents did not have drinking water.

Roger Sutton, CEO of Orion Power, said half the city was still without power but he hoped that by the end of today that 70-80 percent of the city would be back online.

Christchurch Mayor Bob Parker told Breakfast at least six schools would be used as water distribution centres. Water tankers would be sent to them today for people to collect water from. The schools were Lyttelton, Redcliffs, South New Brighton, Shirley, Wainoni and Phillipstown. Steps were also under way to get food supplies in.

Mayor Parker urged people to stay at home, saying the city was effectively "closed" for at least the next three days.

He said portable toilets were being brought into the city to help ease the impact of waste water.

People with minor injuries were advised to go to smaller medical centres around the city rather than Christchurch Hospital, he said.

Christchurch Airport reopened for domestic flights this morning and it is expected the backlog will be cleared by the end of the day.

Christchurch International Airport will reopen for international flights this afternoon, with the first arrival expected at 3.20pm.

Check-in counters will open at midday, but airport chief executive Jim Boult said people should not come out to the airport unless they have a confirmed booking on an international flight.

Aftershocks continued to hit Christchurch overnight, the largest a 4.8 magnitude tremor 10km south-west of the city at a depth of 7km at 9.21pm.

There have been at least 11 more quakes over magnitude 4, with the latest a magnitude 3.6 struck at 10.10am, 10km east of Christchurch, GNS Science reported.


Information about what's been damaged in the aftermath of the magnitude 6.3 earthquake and where people can get help: