Work on dismantling the Timeball Station at Lyttelton is expected to begin on Monday.
The Category One listed building has stood on the hillside of the port since 1876, but was severely damaged in the earthquake on 22 February.
The Historic Places Trust says cranes will arrive on site on Monday.
Demolition is expected to take 12 weeks.
The Trust says a 3D scan of the building has been completed, providing an accurate record of the building remains.
It hopes to rebuild the Timeball Station on the same site.
