January 4, 2024: Several cities situated on the US East Coast are sinking, some up to five millimetres a year, increasing the risk to roadways, runways, building foundations, rail and pipelines, according to a study.
The study focused on coastal communities of the East Coast, including high-density regions like New York, Baltimore, and Norfolk.
It found that an extensive land area—between 2,000 to 74,000 square kilometers—is susceptible to subsidence or sinking rates ranging from 1 to 2 millimeters a year.
This subsidence affects 1.2 to 14 million people and more than half of all crucial infrastructure in major cities along the eastern seaboard.
The hotspots of sinking land intersected directly with population and infrastructure hubs, according to the study conducted jointly by Virginia Tech and the U.S. Geological Survey.
Areas of critical infrastructure in New York, including JFK and LaGuardia airports and its runways, along with the railway systems, were affected by subsidence or sinking rates exceeding two millimetres a year.
“The effects of these right now and into the future are potential damage to infrastructure and increased flood risks.” said lead author Leonard Ohenhen, working at Virginia Tech’s Earth Observation and Innovation Lab.
Some of the cities along the coastline were sinking at a rate of five millimetres a year — a decline that outpaced global sea level rise.
These hard-hit centres included New York City and Long Island, Baltimore, Virginia Beach and Norfolk were seeing areas of rapid “subsidence,” the study published in the Proceedings of the National Academies of Sciences stated.
Digital terrain maps
“Continuous unmitigated subsidence on the US East Coast should cause concern,” said Ohenhen. “This is particularly in areas with a high population and property density and a historical complacency toward infrastructure maintenance.”
The researchers gathered data points from space-based radar satellites to build digital terrain maps. They measured millions of occurrences of land subsidence spanning multiple years.
Then they created some of the world’s first high-resolution depictions of land subsidence.
The new maps showed that a large area on the East Coast was sinking at least two millimetres a year.
Sea level rise
Several areas along the mid-Atlantic coast were sinking up to 3,700 square kilometres, or more than 1,400 square miles, sinking more than five millimetres per year.
That compares to more than the current four millimetres per year global rate of sea level rise.
The researchers measured subsidence rates of two millimetres a year affecting more than two million people and 800,000 properties on the East Coast.
“This information is needed. No one else is providing it,” said Patrick Barnard, a research geologist with the USGS and co-author of the study.