NISAR Satellite Detects Mexico City Subsidence Rates of Up to Half Inch Per Month

-India NISAR satellite, capturing parts of Mexico City sinking by more than half an inch every month. The image, compiled from data collected between October 25, 2025, and January 17, 2026, shows areas of the city and its environs subsiding by up to a few centimeters per month.

@ABC reported the findings, which build on over a century of documented sinking in the capital, home to more than 20 million people living on ground above an ancient reservoir.

Subsidence has caused fracturing in roads, buildings, and water lines in parts of Mexico City, though some areas on volcanic rock remain stable. In the Iztapalapa region, one of the hardest-hit areas, houses founded in volcanic rock remain stable, but those in the middle between the rock and the lacustrine plain are mostly broken, according to Dora Carreón-Freyre, a researcher who has studied the city's sinking for more than 25 years.

In 2017, a taxi fell inside a fracture there.

The NISAR satellite, launched by NASA and the Indian Space Research Organisation on July 30, 2025, from the Satish Dhawan Space Centre, is the first to carry two radar systems at different wavelengths. This allows it to record near real-time ground movement changes from space every 12 days.

David Bekaert, a scientist on the NISAR mission, said the data enables building time series or snapshots of how the ground is moving over time.

Previously, scientists studying Mexico City's land subsidence relied on ground and space satellites that collected annual data. The new technology offers continuous monitoring, which Carreón-Freyre described as amazing for revealing the distribution of differential rates.

She noted that things once learned only by walking everywhere are now captured by this tool, adding that technology is here to help researchers who have spent decades studying the city on foot.

Mexico City's sinking has been documented for more than a century. Engineer Roberto Gayol reported the first finding in 1925, pointing to a large canal and tunnel built to drain water as a potential cause. By the late 1800s, the city was sinking roughly two inches per year, according to a 1995 report by the National Academies of Sciences, Engineering, and Medicine.

The rate accelerated in the 1950s to 18 inches per year, the same report found. Scientists now attribute the subsidence primarily to decades of draining the ancient lakebed aquifer the city was built on. As water is pumped out, the ground above compacts and stays that way, like wet clay squeezed flat and hardened in place.

Not every part of the city sinks at the same rate. Bekaert explained that the compaction causes the ground surface to sink unevenly, with different parts moving at different rates. Parts of Mexico City have lost as much as 30 feet of elevation over the last century, researchers say, while the worst-hit areas have sunk as much as 127 feet.

In a June 15, 2016, file photo, people walked past a slightly tilted historic building in downtown Mexico City, illustrating how the city, built on a drained lake bed, has seen many structures tilt from uneven sinking into soft earth over decades or centuries.

Carreón-Freyre highlighted the urgency of such monitoring beyond Mexico City, citing sinkings in the Philippines at 30 centimeters per year combined with sea level rise. She said what she saw there was really terrible because the two phenomena work together in a very bad way for the population.

Bekaert expressed broader interest in mapping ground motion across coastal zones, where a large proportion of the world's population lives and understanding surface change is particularly important. Scientists say NISAR can now continuously monitor sinking cities anywhere on Earth.