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.
Leonard said stations equipped with GPS data gave an accurate reading of how much the ground had deformed away from the fault line.
He said there was a complicated level of displacement given the fault rupture area was quite large.
"It appears from our flights yesterday it had 10m of slip for a bit of the fault there."
This week's earthquake showed two types of movement in the earth's plates with faults sliding past each other as well as the earth thrusting upwards.
With bad weather hampering flights, scientists were set to send in field teams on the ground to look at the shape of the earthquake.
They would be setting up new instrument sites to measure activity, looking at landslides, dams and rivers and gather evidence of a tsunami on the ground, he said.