"The slip came down, absolutely demolished the house and smothered the occupant in dirt," said a Marahau volunteer firefighter. "It was a disaster zone - demolished, one wall standing."
The firefighter said rescuers did their best to recover Ms Hivon but "it was all in vain". "They finally managed to recover the person involved and administered CPR, but unfortunately it was too late."
Motueka Fire Station chief fire officer Mike Riddell said Ms Hivon may have cried out to her rescuers.
They had yelled out to the woman to see if she was there. "They believe they may have heard someone yelling but then it stopped."
Neighbours had already tried to rescue Ms Hivon, who was the sole occupant of the house, and found her body partially submerged in the mud.
Police said the 200m-long landslide had hit the rear of the house after 18 hours of heavy rain in the area. One wall and the roof were all that remained.
The matter has been referred to the Coroner.
Mr Riddell, who arrived at the scene with another Fire Service crew a short time later, said emergency services were hindered by other slips that had blocked roads around the Kaiteriteri area.
He said the region had been saturated by more than 200mm of rain since Saturday. Other houses close to the destroyed home had been evacuated as a precaution.
A local said Ms Hivon had rented the cottage from Seifried Estate winery.
The slip came as bad weather slammed the country, causing flooding and road closures in the South Island and cutting power to homes in Auckland.
The storm also caused slips in Otago, parts of which were bracing for flooding. Police said State Highway 8 between Clyde and Cromwell was closed from 7pm after rock falls following heavy rain. The road would be reassessed this morning.
The storm also lashed parts of the North Island, with power reportedly cut to 1500 homes in Auckland as strong winds brought down trees.
Earlier in the day MetService put a severe weather watch in place for Northland, Auckland, Waikato, Bay of Plenty, Taranaki, and parts of the South Island.