From the alien invasion to the attack of a giant ape, it’s hard to list all the threats that New York has had to face, at least in works of fiction. But the real Big Apple is not necessarily safe from a much more insidious danger: overweight, and we are not talking about that of its inhabitants.
The city is indeed sinking into the ground, compacting the ground with the tens of thousands of tons of its buildings. And according to a new study that modeled the geology of the city’s subsoil by comparing it to satellite data, the American megalopolis is sinking by 1 to 2 mm per year.
764,000,000 tons
This may seem like very little, but it’s actually significant enough to become worrying, according to the authors of the study, published in Earth’s Future. Especially since some parts of the city are sinking much faster than others. And above all, that New York is a coastal city built on different islands, so its construction is at a very low altitude and it is overpopulated. These populations – up to 8 million people – are therefore threatened by the waters.
“The objective of this article is to raise awareness that each new high-rise building built by the sea, river or lake could contribute to the risk of future flooding. »
Tom Parsons, geologist at the United States Geological Survey
Parsons and his team have calculated the cumulative mass of more than one million buildings in New York City, or 764,000,000 tons of buildings, and this does not count the roads, sidewalks, bridges, railroads which also accumulate the tons. All this weighs, to varying degrees, on New York soils. However, these are of different natures, from rock to loamy sediments, including various levels of sand in their composition. What makes them react differently to the constraints that weigh on them.
Also according to the study by Parsons and his colleagues, soils rich in clay and artificial embankments are particularly prone to subsidence, while the bedrock, which serves as the anchor of many skyscrapers, does not move. as much.
A danger everywhere, and no solution
We have only just identified the problem; it is still very early to imagine solutions to this concern of collapse, which is combined with that of rising waters. Large dikes or retractable dams, as in Venice or on the Thames, are not necessarily possible everywhere.
However, New York is not the only one threatened: a quarter of the Indonesian capital, Jakarta, could be under water by 2050, certain parts of the city sinking by almost 11 centimeters per year due to groundwater extraction. What threaten 30 million people, recalls Science Alert.
2023-05-21 07:00:00
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