New Zealand scientists have now identified the most dangerous parts of Christchurch's Port Hills where further landslips caused by earthquakes or heavy rainfall could see people killed.
GNS Science says it has identified 46 preliminary areas in the hills - where thousands of houses have been built and where there has been mass movement following the 2010 and 2011 quakes - and classed them in order of danger.
There are 15 areas, where 134 houses are under threat, where more research is "a top priority as further mass movement could see lives lost".
Homes and/or critical infrastructure may be severely damaged, the report said.
The remaining 31 areas - affecting about 570 houses - need more study but are not a priority as further mass movement is unlikely to cause loss of life.
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Christchurch City Council has written to the homeowners to tell them whether their property is located either completely, or partly, within the areas.
The council's Mike Theelen says the report will help the council when planning, and could mean stricter control of earthworks, surface and subsurface water control, vegetation clearance and retaining walls in the Port Hills.
The council understood people would be frustrated by the ongoing uncertainty, but decisions involving people's lives and homes needed to be well informed and based on good quality science, he said.
"The Port Hills is a dynamic landscape, and this investigation process following the earthquakes has, and continues to be, complex and time consuming."
Christchurch Mayor Lianne Dalziel says public meetings are planned for people most affected, and council staff will be available to meet with people one on one to discuss what the report means for them.
