Almost four years on from the February 2011 earthquake, 100 homes have been cleared from Christchurch's red-zone in the Port Hills.

Over 270 homes are to be demolished in total.

CERA's acting CEO John Ombler says it's a milestone achievement considering the complexity and risk surrounding each demolition project.

Meanwhile, homeowners who're yet to accept the crown buy-out offer of their homes have just one week to make a decision.