New York City May Be Sinking Under the Weight of Its Skyscrapers
From the Financial District’s sky-high centers of economic power to the pricey pads that rise above Billionaires’ Row, the great volume of towering buildings is part of what gives New York City its identity. But according to new research cited by the New York Post, the weight of those same buildings that give the Big Apple its soaring sense of bravado could contribute to the city sinking.
That’s according to the work of three University of Rhode Island oceanologists and a researcher from the US Geological Survey, who collaborated to publish their findings in the scientific journal Earth’s Future. The scholars first estimated the cumulative weight of New York’s buildings to be 1.68 trillion pounds, and then calculated the downward pressure these buildings exert on the mixture of clay, sand, and slit that make up most of the ground beneath the city’s streets.
Based on their model, New York experiences a “subsidence rate” (the technical term for sinking) of about one to two millimeters per year on average, though Lower Manhattan, as well as particular areas of Brooklyn and Queens, show a propensity for greater subsidence risk. As the authors note in their paper, much of lower Manhattan is currently no more than one to two meters above sea level, possibly exacerbating the effects of climate change in turn.
While one to two millimeters per year may not seem that much, the study’s authors warn that this amount is more than enough to cause major coastal cities serious problems in the future. “The combination of tectonic and anthropogenic subsidence, sea level rise, and increasing hurricane intensity imply an accelerating problem along coastal and riverfront areas,” the paper states. “Repeated exposure of building foundations to salt water can corrode reinforcing steel and chemically weaken concrete, causing structural weakening.”
https://www.architecturaldigest.com/story/new-york-city-may-be-sinking-under-weight-skyscrapers
= new reply since forum marked as read
a bit better over time. 
Serious issue, of course. As is this: "With UN reports estimating that the percentage of the world’s population living in urban areas could increase to as much as 68% by 2050,..." No doubt many are undergoing subsidence already.
IF it hasn't. In any case, current technology should make taking lots of accurate measurements much more doable than in the past. Wouldn't be entirely surprised if there was an app for our smartphones. 