The final bill for the Christchurch earthquake may reach $4 billion, almost double initial estimates, Treasury Secretary John Whitehead said afternoon.

Aftershocks are continuing to hit Canterbury with one measuring 4.1 the latest in a series today that also included a 5.1.

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.

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.

Slips and surface flooding are causing havoc for motorists in the lower North Island as heavy rain and gale force winds sweep the region.

The wild winds forecast for Canterbury tonight are unlikely to reach full force in Christchurch.

Safety first is the message authorities want to convey as many displaced locals face a second night away from their homes.

Christchurch Hospital is already seeing a stream of people with minor injuries from trying to fix their houses.

A list of websites where Canterbury residents can get more information.

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.

Some residents in the earthquake zone may be without power until the end of the week, says lines company Orion.

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

Vodafone is advising customers in Christchurch to keep cellphone calls sort, or preferably use SMS messages.

The Govt will spend $3.5m to upgrade tsunami warning systems across the Pacific, Murray McCully announced today.

Bay of Plenty Civil Defence officials are on flood alert, urging people to be prepared for heavy rain during the weekend.

Three East Coast families will remain isolated for at least another day after their only road access was washed away by heavy rain yesterday.

The rain has stopped falling in flood stricken Otago and Hawkes Bay, but the regions face a big, expensive cleanup.

A large landslip swept through a campground where up to 42 people were sleeping in flood-stricken Central Otago early today.