Mexico City is experiencing significant land subsidence, mapped by the NASA-ISRO Synthetic Aperture Radar (NISAR) satellite, which uses L-band and S-band radars to monitor Earth's surface changes—even through clouds and dense vegetation. Preliminary data from October 2025 to January 2026 indicate some regions are sinking by more than 2 centimeters per month, mainly due to extensive groundwater pumping and the weight of urban development compressing the ancient lakebed beneath the city.
The city, home to approximately 20 million people, has been subsiding for over a century, with parts of the metropolitan area previously sinking as much as 35 centimeters annually in the late 20th and early 21st centuries. This subsidence damages infrastructure, including the transit system. Notably, landmarks such as the Angel of Independence have had steps added to accommodate the lowering ground level.
NISAR's dual-frequency radar instruments—NASA’s L-band radar with a 24 cm wavelength and ISRO’s S-band radar with a 10 cm wavelength—offer detailed and frequent coverage by passing over target areas multiple times per month. This technology allows tracking of subtle movements such as land sinking, uplift, glacier sliding, and agricultural development. The radar functions regardless of weather or light conditions, providing advantages over optical sensors.
Mapped areas with dark blue shading indicate the most rapid subsidence, while yellow and red regions represent residual noise that is expected to reduce as more data is gathered. The analysis includes landmarks like the Benito Juarez International Airport and features linked to the region’s historic water bodies, including the reconstructed Nabor Carrillo lake and the wetlands of Chalco Lake.
These findings confirm that NISAR's measurements meet mission expectations and highlight the satellite's potential for monitoring in challenging environments, including coastal regions affected by both subsidence and sea level rise. Beyond Mexico City, NISAR data will aid global terrain change research and improve disaster response by providing timely pre- and post-event observations.
According to NASA representatives, the images and data demonstrate NISAR’s ability to accurately measure dynamic surface changes, opening new opportunities for scientific study and practical applications in urban planning and environmental management.
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