WASHINGTON (dpa-AFX) - U.S. scientists using space-based radar have found that land in New York City is sinking at varying rates from human and natural factors.
The NASA-led study has also found that a few parts of the New York City metropolitan area are rising due to factors ranging from land-use practices to long-lost glaciers.
Although the elevation changes in a marginal rate of fractions of inches per year, they can enhance or diminish local flood risk linked to sea level rise, scientists have found.
The new study was published in Science Advances by a team of researchers from NASA's Jet Propulsion Laboratory in Southern California and Rutgers University in New Jersey. The team analyzed upward and downward vertical land motion - also known as uplift and subsidence - across the metropolitan area from 2016 to 2023 using a remote sensing technique called interferometric synthetic aperture radar (InSAR). The technique combines two or more 3D observations of the same region to reveal surface motion or topography.
Much of the motion they observed occurred in areas where prior modifications to Earth's surface - such as land reclamation and the construction of landfills - made the ground looser and more compressible beneath subsequent buildings.
Some of the motion is also caused by natural processes dating back thousands of years to the most recent ice age. About 24,000 years ago, a huge ice sheet spread across most of New England, and a wall of ice more than a mile high covered what is today Albany in upstate New York. Earth's mantle, somewhat like a flexed mattress, has been slowly readjusting ever since. New York City, which sits on land that was raised just outside the edge of the ice sheet, is now sinking back down.
The study identified a number of hot spots of land that are subsiding in Queens: runway 13/31 at LaGuardia Airport, Arthur Ashe Stadium, the southern portion of Governors Island, sites near the ocean in Brooklyn's Coney Island and Arverne, Route 440 and Interstate 78 in suburban New Jersey, and in Rikers Island.
The scientists said that cities like New York, which are investing in coastal defenses and infrastructure in the face of sea level rise, can benefit from high-resolution estimates of land motion.
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