When it comes to up to 2cm a month: nasa keeps track as mexico city sinks into the ground, in a striking display of the impacts of urbanization and climate change, Mexico City, built on an ancient lake bed, is sinking at rates exceeding 2 centimeters per month. The new NASA satellite system, NISAR, is tracking this alarming phenomenon in real time, revealing the extent and rapidity of subsidence affecting the city's 22 million residents.
The expansive central Zócalo, a focal point of Mexico City, showcases the effects of this sinking. The grand cathedral, with its soaring spires, leans precariously, while the Metropolitan Sanctuary tilts in the opposite direction. Nearby, the National Palace also appears to be teetering. These structural distortions are not just superficial; they are symptomatic of a deeper, ongoing crisis that has been observed for over a century. Originally reported by The Guardian.
Understanding Up To 2cm A Month: Nasa Keeps Track As Mexico City Sinks Into The Ground
NISAR, short for NASA-Indian Space Research Organization Synthetic Aperture Radar, is one of the most advanced radar systems ever launched into orbit. According to Marin Govorčin, a scientist at NASA's Jet Propulsion Laboratory, "Nisar takes radar imaging observations of Earth to the next level." This satellite can detect even the slightest changes in the Earth's surface, offering unprecedented insights into subsidence, particularly in densely populated areas like Mexico City.
Unlike previous monitoring efforts, NISAR's technology penetrates cloud cover and vegetation, allowing for comprehensive data collection across varied terrains. The implications of this imagery extend well beyond Mexico City, with potential applications in monitoring volcanic activity, earthquake deformation, landslides, and other geological phenomena. Darío Solano-Rojas, an engineer at the National Autonomous University of Mexico (UNAM), noted, "This study of Mexico City speaks to the realm of possibilities that will open up thanks to the Nisar system."
The Rapid Sinking of Mexico City
Some areas of Mexico City are experiencing alarming rates of subsidence, particularly around the main airport, where measurements indicate a drop of more than 2 centimeters monthly-the fastest rate globally. The iconic Angel of Independence statue, erected in 1910 to celebrate Mexico's centenary, is a stark illustration of this issue. Over time, the monument has required 14 additional steps at its base as the surrounding land has sunk.
The ramifications of this rapid sinking are extensive. From warped roads to damaged underground metro systems, the entire urban infrastructure is under stress. Efraín Ovando Shelley, another engineer at UNAM, emphasized the systemic impact: "It affects the entire urban infrastructure of the city: the streets, the pipes for water distribution, the water supply, the drainage pipes."
Roots of the Problem: Groundwater Exploitation
The root cause of Mexico City's subsidence can be traced back to its geological foundation. The city sits atop an ancient lake bed, resulting in a soft, clay-like soil prone to compaction. First documented in 1925, the sinking has escalated due to the over-extraction of groundwater, which is pumped from aquifers beneath the city at a rate far exceeding natural replenishment. Govorčin explained, "As water is withdrawn, the aquifer compacts under the weight of the city above it." Currently, the underground aquifer still supplies about half of the capital's water.
The unsustainable pumping practices have led to the water table contracting by approximately 40 centimeters each year. This creates a vicious cycle, where the city's sinking exacerbates the deterioration of aging water pipes, resulting in an estimated 40% of water being lost to leaks. Coupled with the challenges posed by climate change, including prolonged periods of low rainfall, the city faces a potential crisis where access to clean water becomes increasingly scarce.
Looking Ahead: Challenges and Solutions
Efforts to address Mexico City's subsidence have been limited, primarily focusing on reinforcing the foundations of historic buildings. Experts believe that the data generated by NISAR will help to raise awareness and spur action on this critical issue, but halting the city's descent will not be easy. The trade-offs are stark. As Shelley pointed out, "To stop the sinking, we would have to stop water extraction. And if we stop water extraction, what water are we going to drink?" This dilemma underscores the urgency of finding sustainable solutions to ensure that Mexico City does not continue its perilous descent.
Originally reported by The Guardian. View original.