The full cost of the Canterbury earthquake could be as high as $4 billion, Treasury has revealed.
Treasury Secretary John Whitehead said the $2 billion figure previously used in relation to the cost of the earthquake referred to Earthquake Commission liabilities only.
Treasury's "ballpark" estimate of the total cost to householders, insurance companies, businesses and the Government was double that.
"The cost faced by the EQC, individuals, and insurance costs will probably be of the order of $4 billion," Mr White head said.
In terms of the economic impact it was early days, "but the pattern of these is certainly a short term drop in activity of businesses being unable to function and ... there's always a risk of businesses failing.
"In the slightly longer term when you've got that reconstruction effort, a big amount of that going on tends to raise GDP (gross domestic product)."
But Mr Whitehead stressed that there were a "very wide range of estimates" on costs at the moment because officials were still to "get down to what's actually happened on the ground".
A magnitude 5.1 aftershock, the most strongly-felt since Saturday's big quake, hit at 7.49am this morning at a depth of 6km in the Lyttelton area. It was preceded by a 4.1 magnitude shock and followed by a 3.8.
Experts have warned further large aftershocks could still be to come.
The aftershock forced the closure of the Lyttelton tunnel, which has since been deemed safe and reopened.
Canterbury has received 270 aftershocks of magnitude 3 or above so far since Saturday's destructive 7.1 earthquake, according to GNS Science.
However, GNS seismologist Brian Ferris said people would have felt about 150 of those aftershocks.
This morning's aftershock was one of 10. Aftershocks continued to be felt throughout the day, with a magnitude 4.1 felt about 1.40pm.
Victoria University's Dr John Townend said the number of aftershocks was not unusual considering the magnitude of the initial quake.
"This is what big earthquakes do. They cause aftershocks and they do rattle on for some time so nerves will be frayed."
Dr Townend said Christchurch could still be hit by another large aftershock.
"With an earthquake of magnitude 7.1, like this one, the rule of thumb is you could get aftershocks as large as one unit lower - so magnitude 6.1."
The quakes would probably continue for weeks but he expected they would diminish in strength.
STATE OF EMERGENCY
The state of emergency in earthquake-stricken Christchurch has been extended for a further seven days after a violent aftershock this morning.
Civil Defence spokesman David Miller said the decision to extend the state of emergency, which was due to be lifted today, was made in response to this morning's aftershock.
It means Civil Defence has the power to close buildings and restrict access to certain areas.
No substantial damage was caused this morning, but Civil Defence director John Hamilton the shocks are expected to continue for the next week or more and some buildings still need another assessment.
All buildings in central Christchurch have now been assessed, with some demolitions underway for those deemed "critical."
Sixty-nine percent have been assessed as safe, and others rated as either safe only for limited access or unsafe.
The central business district of Kaiapoi is still being assessed with approximately 22 buildings still deemed too dangerous to enter.
A strong smell of sulphur spreading across Christchurch's eastern suburbs is unlikely to be gas and there was no cause for concern, Civil Defence says.
AFTERSHOCK 'VICIOUS BLOW'
People rushed from hotels and inner city businesses, and power was out in parts of Christchurch.
People were advised not to use lifts in buildings following the latest aftershocks.
Christchurch Mayor Bob Parker said the gut-wrenching intensity of the latest quake reduced many emergency workers to tears and led to the evacuation of the Civil Defence offices.
"It was a devastatingly, vicious sharp blow to the city," he told NewstalkZB.
"This was a terrifying moment. We have just had to evacuate our Civil Defence headquarters.
"We have got staff in tears, we have got fire engines going through the middle of the city, power is out and a lot of people are very, very churned up by that.
"My guts is just churning up here. When will this thing end? It is like living in a maelstrom."
"This is a hammer blow to the spirit of a lot of people."
In Waimakariri, one of the areas most damaged by the quake, council spokeswoman Monese Ball said the continual aftershocks was making life extremely tough for those trying to fix the water and sewage.
"Every time they fix breaks, more breaks appear. They're chasing their tails," Mrs Ball said.
Everyone in the Kaiapoi welfare centre was fine she said, but nerves were beginning to fray.
"It's day four now, a few people are getting quite stressed. The sooner the kids especially can get back to school and some normality, the better."
The Government has set aside $2.4 million for trauma counselling for Christchurch earthquake victims, Social Welfare Minister Paula Bennett said today.
HOSPITAL: OUTPATIENT VISITS CANCELLED
Canterbury District Health Board has cancelled all outpatient clinic appointments at Christchurch Hospital today.
Staff were trying to reach affected patients to reschedule.
Tomorrow's appointments are still expected to proceed, but the situation will be reviewed later today.
Two men in their 50s were seriously injured in Saturday's earthquake. One has since been discharged from Christchurch Hospital. The other remains in a critical condition in the intensive care unit.
LYTTELTON TUNNEL REOPENS
The Lyttelton Tunnel has been deemed "structurally sound" and is now open, after this morning's powerful aftershock caused cracks and forced its closure.
NZ Transport Agency spokesman Peter Connors said the initial assessment of the tunnel had been completed earlier than anticipated.
"Whie some superficial damage has been sustained the tunnel remains structurally sound and safe for use."
Workers were pulling down balustrades from the top of the two-storey 1901 Jacobsen Tiles building at the corner of Moorhouse Ave and Montreal St after parts of them crashed to the street in the aftershock.
"The building has just been earthquake strengthened, that's why the whole building is standing at the moment," said John Small of Consortium Construction.
Christchurch resident Abbie Rilkoff said she felt the aftershock more strongly than Saturday's quake.
"It was really scary. That one did more to our house than the big one, all the glasses moved from the shelves."
Rebekah Martin, 22, was in her Sydenham apartment when the 7:49 aftershock hit.
"The first few (quakes) were exciting - as I am a geography teacher - but now it is getting scary...the novelty is wearing off," she exclaimed.
"The fear is sinking in. That aftershock actually knocked things over in my apartment. My first response was to ring my boyfriend, as he works in a factory. He is okay - thankfully."
She was lying in bed during the shock and ran to the door straight away. She then yelled to her friend, who was staying, to get under the door.
Fiona Fidow said it was the only shock since the big quake that felt as violent and frightening as the first. It was a very sharp shake.
Colleen Simpson said "I'm bloody terrified, all over again."
Tony Stuart, a roofing contractor who lives on the Cashmere Hills, said he was in his office at his home when the latest earthquake hit.
"There was stuff off shelves, the other part of my neighbour's wall has fallen off," a badly shaken Mr Stuart said.
"This is the biggest aftershock we have had. There is stuff falling all over the place.
"It is very scary."
A Stuff reporter in Christchurch said there was a "sudden jolt" and cracks appeared in her hotel room wall, and her power went out.
Christchurch local Hessie Toms said this morning's earthquake was "one hell of a jolt."
"I was just going to go and have a coffee and then all of a sudden I felt this huge shudder."
Mrs Toms who usually works at the Copthorne Hotel, which has been declared unsafe, had been working at another inner city hotel this morning.
"I just said, I'm going home. We never had any cracks in our house before but my husband just rang and we do now."
"It's just a horrible, horrible feeling. You can't sleep because you're worried about earthquakes and then you feel a judder."
"When I got to work this morning at 5am I couldn't hear the birds chirping. That's when I knew the earthquakes were still around."
The emergency centre at the city's art gallery was evacuated after the aftershock, Christchurch City Council spokeswoman Diane Keenan said.
"Everyone is really shaken, I'd say it's pretty serious. The power went off but some of the traffic lights are working again now," Keenan said.
"The jolt was absolutely huge. A really big, stiff jolt. And it was vertical, rather than side to side like the first one. If you were in a car the road moved up and down."
MOBILE PHONE USE
Telephone services have not been badly affected by today's big aftershock in Christchurch but users are still being urged to stay off their cellphones if they can.
Telecom said the aftershock shortly before 8am briefly interrupted services in central parts of Christchurch but most service were soon restored.
The 111 emergency service was fully available. Telecom said its land line and cellular networks were all performing well.
Telecom said its mobile networks dealt with a very high number of calls after this morning's big aftershock and it urged people to minimise the use of mobile phones for anything other than important calls, and to limit the sending of images and video on mobile broadband.
Telecom is not charging for local, national and mobile calls using its payphones around Christchurch but said calls should be brief restricted to important issues.
Chorus, the company which looks after the physical telephone network, said 100 people had been sent to Christchurch to help restore telephone services.
Vodafone said its cellular network was working well and was not under undue stress because of the big aftershock today.
Vodafone spokesman Paul Brislen said some cellular sites were on generators but most were back on mains power.
SCHOOLS REMAIN CLOSED
Civil Defence says all schools in Christchurch city, Selwyn and Waimakariki Districts will remain closed today.
The Director of Civil Defence and Emergancy Management, John Hamilton, said that some schools might reopen on Thursday, but that is a decision that the individual Board of Trustees for each school to make.
Boards of Trustees must consider the safety of the schools when deciding whether to reopen.
Parents can contact their own schools for specific information about the situation there.
More than 400 inmates have now been moved from Christchurch prisons, Corrections Minister Judith Collins said.
She said more than 300 prisoners will move to North Island prisons today by RNZAF Hercules aircraft.
Yesterday 90 prisoners from Christchurch Mens were shifted to Otago. All prisoners from Christchurch Womens were moved to Auckland.
Thirty staff from Auckland and Otago prisons have gone to Christchurch to help with the transfers.
"These temporary relocations were necessary because of safety issues related to lack of water pressure and earthquake damage,'' Ms Collins said.
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