New York sinks. And not in any way. The Big Apple is collapsing in part under the weight of what is probably its greatest source of pride and hallmark: skyscrapers. It may be a shocking statement, but that is the conclusion of a new study published in Earth’s Future after modeling the geology of the American metropolis. Its authors also detail the rate at which the collapse is advancing, and warn: the towers that New Yorkers have erected almost frantically since the 19th century could have a heavy cost for their future.
Your data certainly speaks volumes.
What have the researchers done? Answer several curious and crucial questions: How much do the buildings in New York weigh? And how does that weight affect the city itself? Does any other factor play a role? What Tom Parsons, from the US Geological Survey (USGS), and his colleagues have done is study the geology of the city and compare their data with those collected by satellites.
The objective: to calculate to what extent the weight of the buildings and their pressure can contribute to the “collapse” of the city. The analysis is interesting because —as the researchers themselves explain— the type of soil significantly influences the process. Those rich in clays and artificial fillers are vulnerable; those of a more elastic nature recover better after construction.
And what have they discovered? That New York is sinking. At a rate of between 1 and 2 millimeters per year, to be precise. And that on average because in certain parts of the city scientists concluded that the rate is “significantly higher.” The most interesting thing in any case is not the rhythm, but what provokes it: one of the reasons with which they associate this trend is its enormous buildings.
“Part of this deformation is consistent with the internal consolidation of artificial fill and other soft sediments that may be exacerbated by recent construction loads, although there are many possible causes,” the study continues, recalling two factors: first, that the phenomenon coincides with an increase in sea level; second, that the city is home to a significant volume of population, with more than eight million residents.
A question of soils. The study also stresses the importance of the composition of the terrain, which in turn influences how it responds to the weight of the buildings. Although Parsons and his colleagues note that “the accumulated pressure applied to the ground by large buildings contributes to subsidence” both initially, after the works, and over time and as the construction settles, the characteristics of the terrain have a significant influence. “The results depend on the geology near the surface, as well as the bedrock, which influence the severity and longevity of subsidence,” they abound.
But… How much do skyscrapers weigh? A lot. Regardless of the rate of collapse, perhaps the most striking data produced by the study is an estimate of the accumulated mass of more than a million buildings spread across New York, where emblematic skyscrapers such as the Empire State Building or the Crhysler Building rise up. . Their accounts show a surprising value of 764,000 million kilos. In The Guardian they have used a calculator to present the figure in a manageable way and concluded that it is equivalent to about 140 million elephants.
Such a weight is distributed over an area of about 778.2 square kilometers (km2), which the scientists then divided into 100x100m grids to make it easier to calculate surface pressure. The estimates may be underestimated because they only include the mass of buildings and their contents, leaving out relevant (and heavy) infrastructure such as roads, sidewalks, parks, bridges, or railways.
a touch of attention. The study not only seeks to solve unknowns. Equally or even more important —recognizes Parsons— is to fuel the debate on the convenience of a more sustainable model. “The goal is to raise awareness that each additional high-rise building built in coastal, river or lake settings could contribute to future flood risk,” he muses. The report itself indicates the convenience of drawing up “mitigation strategies.”
And what is the risk? Here’s another key. Especially if, the report stresses, one bears in mind that coastal cities are expanding globally. “The combination of the densification of construction and the rise in sea level imply an increase in the danger of flooding”, he adds: “The city faces an increasing risk of flooding due to the rise in the sea, subsidence and the increase in the intensity of storms due to natural and anthropogenic causes”.
Tom Parsons and his colleagues are the only ones who have warned about the future that New York could face. In 2017, a study supported by NOAA already warned that between 2054 and 2079 the rise in sea level could cause 165 flooding episodes, well above the seven recorded in the period between 1979 and 2004 in the Big Apple. Their analysis further indicates that severe flooding could be three to four times more frequent.
Cover image: Thomas Habr (Unplash)
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