New study reveals lay of the land for entire district
Christchurch City Council Newsline: 22nd October 2025
A new study of vertical land movement is offering a much clearer picture of how the land is slowly rising and sinking post-earthquakes across Christchurch, Banks Peninsula, and beyond.
The study was completed by GNS Science, and builds on earlier ones released in 2023 and 2024. These earlier reports showed that sea-level rise along some parts of the district’s coastline could be happening about twice as fast as previously thought - as a result of increased land sinking following the Christchurch and Kaikōura earthquakes.
Council Team Leader Coastal Adaptation Planning Jane Morgan says there is a much clearer picture now - beyond just the coast - about what is happening across the district and even other coastal parts of Canterbury.
“We now have much more granular and accurate data for the entire district, which provides us with a more localised understanding of how the land has been moving up and down at specific locations.
“This is important, because it means we can consider vertical land movement in the context of local projects, such as when designing stop banks along waterways to help prevent flooding.”
The latest study uses data between 2015 and 2024 – a period three times longer than the previous one – meaning there is higher confidence in the accuracy of the results too, says Ms Morgan.
“We also now have good data for Banks Peninsula, an area where we previously had little to no vertical land movement information, so we really have a much fuller picture now of how the land is slowly shifting beneath our feet.”
Vertical land movement is caused by movements in the earth’s crust. The upward or downward movements can be very fast, such as during an earthquake, or slow and gradual. Local land movements can happen from other processes too, such as liquefaction triggered by an earthquake.
National sea-level rise projections suggest Christchurch could see 14 to 23 centimetres of sea-level rise over the next 30 years. However, in places where land is sinking at about eight millimetres per year, such as parts of Southshore Spit, localised sea levels could rise by 38 to 47 centimetres – around twice as much over the same 30-year timeframe.
In Banks Peninsula, the highest rates of sinking are happening in Teddington and Naval Point (Lyttelton), where the land is sinking at 5 to 6mm a year.
“We understand it’s common for land to keep sinking after large earthquakes,” says Ms Morgan. “While there’s no sign it has slowed down in Christchurch, evidence from other parts of the world tells us that, eventually, the way the land is moving will return to normal. However, it might take another few decades and will depend on whether we experience more large earthquakes.”
Ms Morgan says GNS Science’s latest study, which was co-funded with Environment Canterbury, highlights the importance of early planning and will help inform the Council’s work with communities to adapt public infrastructure and assets, such as roads, pipes, and parks.
“Over time, sea-level rise is going to have a big impact on how we live, use, and move around our coastline and low-lying inland areas. In some places, we’re already seeing the impacts of more frequent and severe weather events.
“As with our adaptation planning for communities in the Whakaraupō Lyttelton Harbour to Koukourarata Port Levy area, we’ll be using this latest information to inform our next steps for planning with other communities in the district.”
Find out more about the Coastal Hazards Adaptation Plan.
Download the GNS Science report about vertical land movement and sea level changes in Canterbury [PDF].
Download the factsheet on what vertical land movement could mean for sea-level rise in different parts of Christchurch and Banks Peninsula [PDF].