Scientists have revealed the extent of uplift on the South Island's northeastern coast, observing that in some places the land was raised by 2m.
The tide gauge at Kaikoura has been lifted up by 1m, while continuous GPS monitoring sites at Kaikoura and Cape Campbell were also raised by 70cm to 90cm.
At this stage, GeoNet estimated the coast was raised between 50cm and 2m from about 20km south of Kaikoura all the way north to Cape Campbell.
Coastal uplift occurs when the land is raised above the sea by tectonic forces, and could happen gradually over geological timescales or suddenly by an earthquake.
Sudden coastal uplift occurred as the result of large earthquakes.
Vertical movement on a fault could cause land to be pushed up - a type of movement that had built many of New Zealand's mountain ranges in New Zealand.
When such vertical movement on a fault happened near the coast, land was raised above sea level.
``Sea level is a powerful horizontal marker for measuring tectonic movement because it is very obvious which land used to be under water before the earthquake,'' GeoNet reported in a new blog post.
Coastal uplift was normal for large earthquakes near the coast that included some vertical movement on a fault.
Most movement on the faults that ruptured in the Kaikoura 7.8 earthquake was horizontal, but, as there was vertical movement as well, it was not surprising there had been coastal uplift in the event.
In New Zealand, there was evidence preserved in the landscape that showed many parts of the coast had been repeatedly uplifted through time.
Raised marine beaches and terraces along the Kaikoura Peninsula, Wairarapa coast, Cape Kidnappers, Mahia Peninsula, north of Gisborne and East Cape offered evidence of former beaches that were uplifted from the sea by earthquakes in prehistorical times.
Many of these had been or were currently being studied to find out the size and age of past earthquakes.
``In historical times we have had several examples of earthquakes causing coastal uplift that, although devastating in the short term, have led to some benefits.''
For example, in 1931 the 7.8 Hawkes Bay earthquake raised land around Napier by 1m-2m above sea level.
Land that was once an estuary now provided space for Napier airport.
Further, the road from Wellington city to the Hutt Valley became viable as a result of the new land around the harbour's edge raised by the 8.2 magnitude Wairarapa quake in 1855.
It was unlikely the newly raised ground at Kaikoura would also go down, and it would most likely become a permanent feature.
This would mean a major shift in the local community of marine species, as many seaweeds and animals that would normally be permanently covered by water would now be struggling to exist in a zone of transition between air and sea.
Some of the animals that had been raised would be accustomed to air exposure for short periods of time, but not the full tidal cycle they would now experience.
``As the animals not suited to this environment die from the reef, they will be replaced by seaweed and animals appropriate for the new tidal level.''
There were now several studies being planned by geologists and biologists, who would be undertaking surveys over coming weeks.
``Recording this information will help us to understand which faults ruptured in the earthquake, and how much slip occurred on those faults.''
People could help by sharing their pictures of displaced coastal features such as the uplifted reefs and rock platforms; displaced marine life especially before and after photos if animals are being rescued and removed from the reefs, and uplifted man-made structures such as jettys and boat ramps particularly if they have tide level markers on them.
``We are also interested in people's observations, particularly residents who have familiarity with the coastline pre and post-earthquake,'' GeoNet stated.
``To be of most use, we would like to know the location, date, time of the photograph and if possible, context and scale.''
``As always your safety comes first, please do not put yourself at risk to collect this information.''
- Pictures and information can be sent to k.clark@gns.cri.nz
