The government and Christchurch City Council will buy 16 Port Hills properties.
"The latest council-commissioned GNS Science reports show 37 green-zoned homes are in areas where the risk to life from mass movement (sometimes called landslide) is considered intolerable,” according to a council media statement.
An intolerable risk is defined when “the risk to life from mass movement in any one year is equal to or greater than one in 10,000.”
Geonet identified 37 at risk properties in total.
The council says it has identified an engineering solution to remediate the land and reduce the risk for the other 21 properties.
There are also 89 properties in “mass movement” areas that have already been red-zoned by the Crown for cliff collapse or rockfall.
A full copy of the GNS reports is available at www.ccc.govt.nz/porthillsgeotech