The Christchurch Mayor has warned the rest of NZ that they are not immune from the type of natural disaster that struck his city this week.

A second big earthquake in three days sent lower North Island residents scrambling for cover.

Four Canterbury All Blacks, including captain Richie McCaw, have been enlisted for a campaign to help quake victims.

Water restrictions have been lifted for Christchurch and Banks Peninsula but some Waimakariri residents must still boil their water and their river is contaminated.

When the tremors return, residents at one Christchurch rest home band together with cups of tea and company.

At least 22 commercial properties and 50 homes in the small quake-damaged North Canterbury town of Kaiapoi have been deemed unsafe, with its mayor admitting the town is changed forever.

Most schools in the quake-devastated Canterbury region are not likely to open until Monday, the Education Minister says.

Mayor Bob Parker says Christchurch city is coping "amazingly well" with the continuing fall-out from Saturday morning's earthquake.

The Government has set aside $2.4 million for trauma counselling for Christchurch earthquake victims, Paula Bennett says.

The state of emergency in Christchurch has been extended a further seven days following an aftershock of 5.1 on the Richter scale this morning.

A golden retriever puppy needed emergency surgery after cutting off the side of his nose running away in panic when the quake hit.

An open source online map has been set up to help Cantabrians find help nearest to them.

Stricken homeowners and workers will start receiving compensation and emergency payouts within days as Christchurch's earthquake bill threatens to exceed $2bn.

Rebuilding up to 100,000 damaged and destroyed homes in quake-hit Canterbury could take years, a building executive says.

Mayor Bob Parker is unsure about the comparison with former New York mayor Rudy Giuliani, but the earthquake that struck Christchurch could help him keep his job.

Christchurch was "inevitably going to be brought to its knees" by an earthquake because of the nature of the ground it stands on, a scientist says.

"It's essentially a ghost town. You can see utter devastation," said Prime Minister John Key.

"It was like a giant had picked up our house and was just shaking it, shaking and shaking," said one resident.

Services and infrastructure in Christchurch have been seriously affected by this morning's quake. Here is the current situation.

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