It could take up to two weeks for geo-technical engineers in Wellington to decide if at least two houses in the suburb of Berhampore need to be condemned, after a huge landslide on Saturday.
The council says residents of six properties have been able to return to collect valuables but it will be several more days before they can return for good.
It says dealing with two houses hanging over the slip will take longer and it is unclear whether they can be saved.
One hundred and ten people were evacuated from 25 houses and a rest home in the path of the slip on Saturday morning.
Wellington City Council is hoping to fly a remote controlled helicopter around the slip to obtain close-up images so the damage can be assessed.
Experts from GNS Science, the Earthquake Commission and geotechnical engineers need to examine the foundations of houses and the slip face.
Police were called to the address in Priscilla Crescent at 4.45am by a resident who said the hill behind his house had started to give way.
Priscilla Crescent and Breton Grove are the worst affected and also Halifax Street.
A Radio New Zealand reporter at the scene said the slip, which can be seen from the deck of a house in Breton Grove, stretches more than 100 metres down the hill. It is an estimated 40 metres wide.
It is a horseshoe-shape behind houses on Priscilla Crescent and Breton Grove.
Emergency services fear more houses could be at risk as the slip is still moving with trees continuing to fall.
Civil Defence and other agencies were called to provide emergency accommodation.
Incident controller Senior Sergeant Shannon Clifford said the slip is so big that whole pohutukawa trees have fallen.
Wellington City Council spokesperson Richard Maclean said the slip looks terrifying:
"The worrying thing at the moment is that the slip is still pretty active; there's been a couple of trees have gone down, there's been a lot of spoil in the past few minutes, so clearly it's still a bit of a dynamic situation yet."
He said the slip is still moving and the situation is serious.
Mr Maclean said the rest home was not directly affected, but the slip could cut its access if it came down further.
Some evacuees have gone to friends and family and others have been taken by ambulance to a Civil Defence hall in Newtown.
Earlier, acting shift commander Bruce McKay said a burst watermain appears to have caused the problem.
Council workers are at the scene, along with police and other emergency services.
No injuries are reported.
Some residents had to leave their homes still in their pyjamas.
Some said the sound of falling rocks was so loud that they thought it was an earthquake.
Rhia Williams, a tenant at one of the houses thought to be in danger, said she heard rushing water on Friday night and was kicking herself that she didn't do anything about it.
Council staff have shut off the watermain and part of Priscilla Crescent is being dug up as engineers can try to establish which part of the watermain or sewer is involved.
Civil Defence says some of the people evacuated from their homes have been allowed back into their properties to collect vital belongings.
The visits were supervised by Civil Defence personnel who accompanied them and the residents were not allowed to stay.
City Operations manager Stavros Michael said residents of six properties have been able to collect valuables and it will be several more days before they can return for good.
But, he said, dealing with houses hanging over the slip will take longer.
Mr Michael said it is likely to be at least two weeks before it's decided whether the houses can be reinstated or have to be condemned.