IBNS-CMEDIA: Mexico City is sinking by nearly 10 inches (about 25 cm) a year, according to new satellite imagery released this week by NASA, making it one of the fastest-subsiding megacities in the world.
Spanning roughly 3,000 square miles (7,800 sq km), the metropolitan region is home to around 22 million people. The findings highlight the capabilities of the NISAR satellite (NASA-ISRO Synthetic Aperture Radar), which can track real-time changes in Earth’s surface from orbit, even through cloud cover and dense vegetation.
According to NASA, the city is built atop an aquifer, and decades of excessive groundwater extraction—combined with the sheer weight of urban development—have led to the gradual compaction of the ancient lakebed beneath it. This process has been ongoing for more than a century.
“Images like this confirm that NISAR’s measurements align with expectations,” said Craig Ferguson. He added that NISAR’s long-wavelength L-band radar will help detect and monitor subsidence in challenging environments, including coastal regions where land sinking may combine with rising sea levels.
The latest analysis is based on preliminary NISAR data collected between October 2025 and January 2026 during the city’s dry season. Areas subsiding by more than half an inch (over 2 cm) per month appear in dark blue in the imagery, while yellow and red patches are likely residual noise expected to diminish as more data is gathered. Key landmarks visible include Benito Juárez International Airport and Lake Nabor Carrillo.
One of the most visible indicators of subsidence is the Angel of Independence along Paseo de la Reforma. Built in 1910 to mark 100 years of Mexico’s independence, the 114-foot (36-meter) monument has had 14 steps added to its base over time as the surrounding ground gradually sank.
“Mexico City is a well-known subsidence hotspot, and images like this are just the beginning for NISAR,” said David Bekaert, noting that the mission is expected to generate a wave of new global discoveries.
ISRO connection
NISAR satellite is a joint Earth-observation mission developed by NASA and the Indian Space Research Organisation (ISRO). The satellite was launched from Satish Dhawan Space Centre on India’s southeastern coast.
The mission is managed by Jet Propulsion Laboratory, with NASA providing the L-band SAR system and antenna reflector, while ISRO supplied the spacecraft bus and S-band SAR.
Notably, NISAR is the first satellite to carry two synthetic aperture radar (SAR) instruments operating at different wavelengths. It scans Earth’s land and ice surfaces every 12 days using a massive 39-foot (12-meter) drum-shaped reflector—the largest radar antenna ever launched by NASA.
