A global study reveals dramatic differences in urban ground subsidence rates, with cities like Medan sinking 33 mm annually, while others like Paris show minimal movement.
Global study reveals uneven ground sinking
A global study led by researchers from Peking University has identified significant variations in the rate of urban ground subsidence across 465 cities with more than one million inhabitants, spread across 107 countries, between 2014 and 2023.Advanced technology tracks ground movement
The research, published on October 12, 2026 in the journal Nature Cities, used radar interferometry (InSAR) applied to Sentinel-1 images from the European Copernicus program to measure vertical ground movements. This technique allows scientists to detect even minor changes in the Earth's surface.Some cities sink faster than others
The findings indicate that certain cities, such as Medan in Indonesia, Bandung in Indonesia, and parts of Mexico, are experiencing the fastest subsidence rates, with Medan averaging approximately 33 mm per year. In contrast, cities such as Paris, Lyon, and Marseille in France show subsidence rates of less than one millimeter per year, near the limit of detection by the method used.Groundwater pumping is a major cause
The study highlights that intensive pumping of groundwater is among the main causes of subsidence, as sediment layers compress when deprived of water. In Mexico City, some neighborhoods are sinking at a rate of about 217 mm per year, according to data from the NISAR satellite, launched in July 2025 by NASA and the Indian Space Research Organisation.Some regions show signs of improvement
In Southeast and East Asia, many cities are slowing their descent, suggesting that large-scale mitigation measures may be effective, while other urban areas in these regions continue to experience accelerated subsidence. The study also emphasizes that areas in Africa, South America, and Russia have been largely neglected in previous research.Limitations and resources for further study
The research team acknowledges limitations in their study, including the focus on administrative city boundaries and the reliability of measurements in areas with few ground-based GPS stations. The 465 cities analyzed in the study are accessible via an interactive portal called GUS, provided by the researchers.
