Scientists say this week's earthquake has seen parts of the South Island move 10 metres.
GNS senior scientist Graham Leonard said an aerial survey of quake-ravaged regions showed massive movement at a section along one fault line following Monday's magnitude 7.5 tremor.
The biggest rupture scarring the land has been spotted on the Kekerengu fault line near Blenheim.
"In terms of fault rupture movement initial reports from the team say there was up to 10m of movement along it at one place," said Leonard.
A GNS monitoring station at Cape Campbell at the top of the South Island recorded a 2m shift to the north.