InSAR to monitor fault-related ground movement: An effective approach for urban environments

Fault movements, even when gradual and subtle, can significantly impact the stability of urban infrastructures, posing challenges for construction. This study uses Interferometric Synthetic Aperture Radar (InSAR) to monitor and analyze ground deformation affected by fault activity in several urban areas undergoing constant development: Silver Creek Fault (California, USA), Santa Monica Fault (California, USA), the Para Fault Zone (Adelaide, Australia), and a fault located in the Canary Wharf area, in the city of London (UK).

In urban environments, monitoring surface motion and ground stability is critical due to high population density and complex land use, which increases vulnerability in the area. Traditional in-situ monitoring approaches face a challenge when analyzing large areas and moreover to detect ground displacement movements over a larger area. In this regard, satellite remote sensing techniques offer an advantage to analyze fault-related ground displacement across entire cities or large urban areas due to the large spatial coverage of satellite imagery compared to only-ground instrumentation traditional methods.

Specifically, InSAR offers a reliable, non-intrusive approach for detecting subtle fault-related movements. When utilizing high-resolution sensors, this technique effectively evaluates ground displacement with millimetric precision (1–2 mm) and achieves geolocation accuracy within metrics scales (1–2 m). This allows the analysis of the fault-related ground deformation in detail, even at the scale of a single infrastructure.

The different case studies presented in this work show the effectiveness of InSAR not only to identify faults and their impact on urban areas, but also to quantify ground movements linked to fault areas, this is movements not only caused by fault displacement but affected by them, such as deformation caused by groundwater extraction. The study also shows how fault zones may affect these deformations by either amplifying or physically limiting them.