NASA has released new satellite images showing that Mexico City is sinking at an alarming rate of nearly ten inches per year. The sprawling metropolis, covering about 7,800 square kilometers and home to roughly 22 million people, was built on the surface of an ancient lake. Many of its central streets were once canals, and the city’s foundation is now suffering from severe subsidence.

According to NASA’s latest report, some areas, including the main airport and the Angel of Independence monument, are sinking at an average rate of 0.78 inches per month. Geophysicist Enrique Cabral from the National Autonomous University of Mexico noted that the city has sunk more than 39 feet in less than a century due to excessive groundwater extraction and urban development. The shrinking aquifer has also caused a persistent water shortage.

For decades, authorities have largely ignored the problem except for stabilizing foundations under landmarks such as the Metropolitan Cathedral. Recently, as the water crisis worsens, the government has begun funding further research into the issue.