MEXICO CITY is sinking. And sinking fast. A newly operational Earth-observing satellite is now delivering centimeter-level measurements of how the planet’s surface is shifting, and one of its early targets shows just how severe urban subsidence can be.
First reported by Keith Cooper for Space.com on May 5, the NASA-ISRO Synthetic Aperture Radar (Nisar) is now fully operational and mapping ground deformation worldwide, including in Mexico City.
Launched on July 30, 2025 through a joint effort between NASA and Indian Space Research Organisation, Nisar is built to monitor changes across Earth’s surface in near real-time. Its capabilities span land subsidence, glacier retreat, tectonic shifts, and wildfire spread, all measured with accuracy down to about a centimeter.
“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 of the Flemish Institute for Technological Research.
The city’s long-documented subsidence traces back to its foundations. Much of the metropolis sits on an ancient lakebed, where water-saturated sediments compress as groundwater is extracted and as the weight of urban expansion increases. Some areas are sinking by as much as 35 centimeters per year, placing sustained pressure on infrastructure such as buildings and the metro system.
“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 effect of both land subsidence and sea level rise,” said Craig Ferguson of NASA Headquarters.
The satellite’s strength lies in its dual radar system. NASA developed the L-band radar, which can detect subtle shifts in bedrock and ice, while ISRO contributed the S-band radar, optimized for monitoring vegetation and surface changes. Together, they provide a layered view of environmental transformation.
Orbiting Earth every 12 days, Nisar uses synthetic aperture radar to build high-resolution images by combining thousands of radar pulses per second. These signals are captured by a 12-meter reflector, the largest radar antenna NASA has placed in space.
Early imagery over Mexico City shows a mosaic of color-coded ground movement. Blue areas indicate zones that dropped by more than two centimeters between October 2025 and January 2026, while green and yellow regions reflect residual noise that is expected to diminish as more data is collected.
“Images like this confirm that Nisar’s measurements align with expectations,” Ferguson added.
Mexico City’s rapid subsidence makes it an ideal proving ground. The scale of the problem is reflected in Angel of Independence, a landmark that has required 14 additional steps since its completion in 1910 to compensate for the gradual sinking beneath it.
“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,” Bekaert said.
