Much of Christchurch and its surrounding towns remain on the edge - and in lock-down mode - following Saturday’s 7.1 magnitude earthquake. And curfews for public safety remain in place.

Tens of thousands of workers, school children and residents have been warned to stay home as authorities continue the massive job of assessing the damage to buildings and crucial infrastructure.

Civil defence has extended its state of emergency until Wednesday.

Federated Farmers Adverse Events spokesperson David Rose warns the natural disaster is far from over.

“The short term things like milking cows and things are sorted – there was a bit of a scramble to get things like power supplies and generators and platforms working," said Mr. Rose.

"Now we’re expecting the next wave to come in and things, securing houses and putting tarpaulins over wherever they’re needed.”

Agriculture Minister David Carter said, "Out in the rural areas, you’ve got house completely destroyed or uninhabitable, milking platforms that have come off their rollers, and of course the underground irrigation systems which are prevalent in this area, they’re buried about a metre under the ground, and at this stage we have no idea how damaged they are."

"We’re aware of one shed in the area that was designed for 400 cows, that in the day after the quake milked over two thousand cows, and others that ran well into the night and early morning to ensure the neighbours cows were milked."

"They’re running on adrenaline at the moment, there’s a lot of tired people out there, and I don’t think things have sunk in for a lot of people yet," said the Agriculture Minister.