NISAR Reveals Mexico City Sinking at Alarming Rate Per Month

The findings, based on early observations from the NISAR (NASA-ISRO Synthetic Aperture Radar) satellite, underscore both the severity of the capital's long-running subsidence crisis and the growing capability of space-based monitoring systems to track ground movement in near real time, a NASA media release said Wednesday (local time).

Mexico City, home to nearly 20 million people, has been sinking for more than a century due to intensive groundwater extraction and the weight of urban development compressing its ancient lakebed foundation. Historical data show that some areas subsided by about 35 centimetres per year in the late 20th century, damaging infrastructure, including roads, buildings and the city's extensive Metro system.

The new NISAR data, collected between October 2025 and January 2026, reveal that certain areas are now sinking by more than 2 centimetres per month, NASA said.

The satellite's advanced radar system can penetrate cloud cover and vegetation, allowing it to track subtle surface changes regardless of weather or lighting conditions, it added.

"Images like this confirm that NISAR's measurements align with expectations," said Craig Ferguson, deputy project manager at NASA Headquarters. "NISAR's long wavelength L-band radar will make it possible to detect and track land subsidence in more challenging and densely vegetated regions such as coastal communities where they may have the compounding effects of both land subsidence and sea level rise."

The satellite is capable of observing Earth's land and ice surfaces twice every 12 days. Its dual-frequency radar system -- the first of its kind -- enables scientists to monitor a wide range of geophysical processes, including sinking land, shifting glaciers and agricultural changes.

One visible indicator of Mexico City's long-term subsidence is the Angel of Independence monument. Built in 1910, the structure has required the addition of 14 steps at its base over time as the surrounding land levels dropped.

"Mexico City is a well-known hot spot when it comes to subsidence, and images like this are just the beginning for NISAR," said David Bekaert, a project manager at the Flemish Institute for Technological Research and a member of the NISAR science team. "We're going to see an influx of new discoveries from all over the world, given the unique sensing capabilities of NISAR and its consistent global coverage."

The mission represents a major collaboration between the United States and India, with NASA's Jet Propulsion Laboratory leading the US contribution and ISRO providing key spacecraft components. The satellite was launched in July 2025 from India's Satish Dhawan Space Centre.

- IANS