Mexico City was built on a lake. Over the centuries most of the lake has dried up. The problem now is the city is sinking.
We already knew that and even a tourist can notice it. I remember visiting Mexico City and seeing an old colonial church with one side lower than the other. It was sinking.
Now there is new NASA footage which shows it.
From the Daily Galaxy: “Parts of Mexico City are sinking by more than half an inch every month, and a newly launched radar satellite has now measured exactly where. Data released April 29 by NASA’s Jet Propulsion Laboratory shows the NISAR satellite tracking urban land subsidence across one of the world’s largest cities with a level of detail that earlier space-based systems could not consistently achieve in dense or cloudy environments.”
NISAR is a satellite jointly developed by NASA and ISRO (the Indian Space Agency). It was launched in July 30th, 2025 from India’s Satish Dhawan Space Centre. NISAR sounds like an Indian word but it’s actually an English acronym for NASA-ISRO Synthetic Aperture Radar.
“The readings were taken between October 2025 and January 2026, during Mexico City’s dry season. Areas sinking fastest appear in dark blue on the published imagery, with some zones recording ground subsidence exceeding two centimeters per month. Benito Juarez International Airport sits at the center of the frame, with Lake Nabor Carrillo visible to the northeast.”
“…Mexico City is built on a drained ancient lakebed, and relentless groundwater pumping combined with the weight of development above has compacted the soft sediment beneath it for generations. An engineer first documented the sinking in 1925.”
“By the 1990s and 2000s, parts of the city were dropping roughly 14 inches, or 35 centimeters, per year, enough to fracture Metro tunnels, buckle roads, and split water mains across the metropolitan area. The damage is not cosmetic. It accumulates in infrastructure that serves millions of people daily, and the sediment driving it has no natural mechanism for recovery once compressed.”
The article explains why this radar satellite was an advance over previous radar satellites.
“Previous radar satellites have tracked Mexico City’s subsidence, but with real limitations. Cloud cover, dense vegetation, and darkness all degrade optical sensors and higher-frequency radar systems. NISAR’s L-band radar, operating at a 24-centimeter wavelength, cuts through all three without losing signal quality.”
“The satellite also carries an S-band instrument at 9.4 centimeters, making it the first ever launched with a dual-frequency synthetic aperture radar configuration. Together, the two instruments give researchers more ways to separate genuine ground motion from atmospheric interference, improving confidence in the measurements, particularly in regions where a single instrument would struggle.”
“It passes over the same point on Earth’s surface twice every 12 days, building a consistent record that researchers can compare over time to detect motion measured in millimeters. Craig Ferguson, deputy project manager at NASA Headquarters in Washington, said the Mexico City imagery confirms the sensors are performing as designed. He pointed specifically to the L-band’s value for coastal regions where land subsidence and rising seas occur simultaneously, compounding flood risk in ways that are difficult to untangle without precise ground-movement data.”
Then there’s NISAR’s antenna reflector:
“The satellite’s most striking physical feature is its antenna reflector: a drum-shaped structure 39 feet, or 12 meters, across. NASA calls it the largest radar antenna reflector ever sent to orbit. A wider antenna captures more of the returning radar signal, which translates directly into finer surface measurements across larger areas, a critical advantage when the goal is detecting motion of just a few millimeters across an entire city.”
There’s more to be done.
“The Mexico City results are preliminary. JPL [Jet Propulsion Laboratory] notes that the yellow and red areas visible in the imagery are likely noise artifacts that should diminish as the mission collects more passes and builds a stronger baseline. The dark-blue subsidence zones, by contrast, align with decades of prior measurements and the known behavior of compressed lakebed sediment.”
“David Bekaert, a project manager at the Flemish Institute for Technological Research and a member of the NISAR science team, called Mexico City a proof-of-concept for what the satellite will do worldwide. ‘Mexico City is a well-known hot spot when it comes to subsidence, and images like this are just the beginning for NISAR,’ he said. ‘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.’ ”
“NISAR data is archived and openly accessible through the Alaska Satellite Facility DAAC. Mexico City’s next dry season will produce another comparable set of measurements, giving scientists a cleaner year-over-year look at how the city’s sinking lakebed is responding — or not — to any changes in water use or urban load above it.”
By the way, Mexico City is not the only sinking city in the world. Others include Jakarta, Indonesia; Lagos, Nigeria; Dhaka, Bangladesh; Venice, Italy; Bangkok, Thailand; Rotterdam, the Netherlands; Alexandria, Egypt; and in the United States: Houston, Virginia Beach, New Orleans and Miami, Florida.
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