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Sixense monitoring of expansiv...
Sixense monitoring of expansive soils from space
Leveraging TerraSAR-X imagery and InSAR analytics to identify risks to buildings and infrastructures in Auckland
Challenge
In many areas worldwide, expansive soils swell and shrink depending on moisture and temperature conditions, generating ground deformation that can damage foundations, roads, tunnels and underground utilities. Auckland Council was seeking a solution to assess the risks that climate change and expansive soils pose to buildings and infrastructures across the region.
Traditional ground surveys and field instrumentation are effective at a local scale but are difficult and expensive to deploy across an entire metropolitan area. The challenge was therefore to continuously monitor hundreds of square kilometres and identify seasonal deformation patterns linked to changes in soil moisture.
Our solution
Satellite imagery enables non-intrusive and long-term monitoring over large urban areas. The project focused on using TerraSAR-X imagery to support Auckland Council’s climate adaptation and infrastructure risk management strategy. Sixense's proprietary Atlas InSAR solution was deployed to assess ground motion with millimetric precision across the entire Auckland metropolitan area, which extends over more than 450 km². The results were further enhanced using Atlas+, Sixense’s suite of advanced analytics and alert systems, transforming InSAR measurements into actionable information tailored to infrastructure risk assessment and decision-making.
A set of 48 high-resolution images acquired between 2019 and 2021 was used, providing displacement measurements at building scale.
Sixense generated more than 7.6 million ground-motion time-series points with densities reaching 40,000 measurement points per km² in some highly urbanised sectors. Sixense also combined external information, such as climate data and geological layers, with time-series analysis techniques to evaluate the impact of expansive soils on infrastructures and buildings.
Results were aggregated at the building level using more than 500,000 cadastral footprints and integrated into the Beyond Monitoring platform through heatmaps, deformation indicators and risk layers. Atlas+ analytics supported the interpretation of deformation patterns and risk indicators, making large-scale datasets easier to analyse and act upon. Satellite measurements were validated against in-situ instrumentation deployed on Auckland’s City Rail Link project.
Benefits
Scalable urban monitoring
TerraSAR-X imagery enabled continuous monitoring of a large urban area without installing equipment on every asset. Compared with traditional surveys, this approach reduced field operations while covering a much larger area.
Early deformation detection
The X-band imagery allowed Sixense to detect subtle ground movements before visible structural damage occurred and to track deformation trends over time using both historical and current data.
Clients highlighted the rapid mobilisation of teams, comprehensive reporting and the ability to visualise and analyse large datasets through the Beyond Monitoring platform. Historical and current InSAR data also helped stakeholders assess and communicate infrastructure and building deformation risks.
Integrated risk intelligence
By combining satellite data, data analytics and ground instrumentation, the project delivered actionable information to support risk management, infrastructure maintenance and climate resilience planning.
Organisation involved
Sixense is an international company specialised in monitoring infrastructure, buildings and the natural environment.
Sixense Satellite, established in Barcelona in 2018, centralises the group’s satellite monitoring activities and focuses on displacement monitoring using satellite-based InSAR technologies. The company provides monitoring services to governments, infrastructure operators, private companies, and international institutions for risk reduction and asset management.
