According to a new research, New York City, a bustling metropolis famous for its tall skyscrapers, is sinking and rising at variable rates as a result of both natural and human forces.

Researchers from Rutgers University and NASA's Jet Propulsion Laboratory examined vertical land motion in the metropolitan region from 2016 to 2023 using a remote sensing method called interferometric synthetic aperture radar (InSAR).

The scientists found that a large portion of the motion was recorded in regions where previous alterations to Earth's surface, such landfill development and land reclamation, rendered the ground underneath future structures more compressible.

Furthermore, part of the motion has been linked to natural processes that go back thousands of years to the most recent ice age.

New York

New York City, which is situated on ground that was uplifted just beyond the margin of the ice sheet, is now sliding back down as the Earth's mantle slowly readjusts from the weight of the ice sheet that formerly covered New England.

The metropolitan region sank by around 1.6 millimeters annually on average. But the scientists were able to identify certain areas and landmarks that are receding more quickly than usual. For instance, Arthur Ashe Stadium is sinking at a pace of around 0.18 inches per year while LaGuardia Airport's runway 13/31 is subsiding at a rate of about 0.15 inches (3.7 millimeters) each year.

It's interesting to note that the team also located areas of improvement in Woodside, Queens, and East Williamsburg, Brooklyn. In these places, the annual increases are 6.9 millimeters and 1.6 millimeters, respectively.

Groundwater pumping and injection wells used to clean dirty water may have contributed to this rise, which's cause is yet unknown.

These discoveries are especially important because the world's oceans are rising due to the Earth's changing climate, which increases the frequency of nuisance flood occurrences and exacerbates devastating storm surges.

This study's precise map of vertical land motion in the New York City region can be very useful for planning and mapping floods.

High-resolution estimates of land motion can offer crucial information for these initiatives as cities like New York invest in coastal fortifications and infrastructure in response to sea level rise.

New York City is sinking at a pace of 1 to 4 millimeters each year, according to research from the University of Rhode Island Graduate School of Oceanography. The researchers discovered some regions with much increased sinking rates, which may be connected to the enormous weight of the structures, even if this decline is compatible with natural subsidence in the area. The study, which is part of an expanding body of research on how waterfront communities are dealing with sinking land as well as rising waves, was headed by Tom Parsons of the U.S. Geological Survey with the help of GSO professors Meng (Matt) Wei and Steven D'Hondt and GSO Ph.D. student Pei-Chin Wu.

Since the end of the last ice age, subsidence has been happening where New York City is currently located. The area that had been covered by the ice sheets north of the city started to rise as the ice sheets receded, while the region immediately south of the ice, where New York City is now, started to sink. This reaction to the ice sheets melting is still going on today.

The goal of the study team was to gain a better understanding of how the massive construction infrastructure of the metropolis affected this steady drop. In order to get the answer, the team first computed the downward pressure brought on by the weight of the more than a million structures in New York City, which together weigh 1.68 trillion pounds.

The underlying geology of New York City ranges from solid bedrock to sand and clay layers, which may compress more readily, thus how the ground responds to this pressure is not consistent. In order to track elevation changes in the area, the scientists also employed radar photos of the Earth's surface taken from orbiting satellites.

According to the findings, post-glacial relaxation is causing New York City as a whole to sink by 1 to 2 millimeters annually. However, certain areas of the city are sinking quicker, up to 4 millimeters each year, notably those where structures are constructed on fill and silt. Even while the structures' enormous weight contributes to some subsidence, not all of the increased subsidence rate can be traced back to them. The study found that building-related subsidence often ends a year or two after completion. Subsidence that persists after that is mostly caused by other processes, such groundwater extraction.

As coastal communities expand quickly, the combination of increased development density of sea level rise makes them more susceptible to floods. The report claims that New York is representative of expanding coastal cities that are found to be sinking all over the world, indicating that there is a common worldwide problem of mitigating against an increasing flooding threat.

“The silver lining of this unfortunate situation is that thoughtful planning for recovery from flooding by major storms can be used to pre-adapt coastal regions for the long-term consequences of sea level rise and coastal subsidence,” said D’Hondt.

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