Land Subsidence in U.S. Cities: An Emerging Threat
The ground beneath many U.S. cities, including New Orleans, New York City, Miami, and South San Francisco, is sinking. This phenomenon, known as land subsidence, poses a significant threat to the integrity of buildings and critical infrastructure such as railroads and airports. With the added challenge of rising sea levels, the risk of flooding and associated damage is heightened.
The Impact on Home Values and Infrastructure
Land subsidence can directly affect home values, with homeowners potentially losing up to 6% of their property’s worth. In areas experiencing high rates of subsidence, this number can increase to 8.1%, as found in forthcoming research led by Mehdi Nemati, an assistant professor of public policy at the University of California, Riverside. While this study focused on California’s Central Valley, Nemati suggests that the findings could be applicable nationwide.
Insurance and Financial Strain
Standard homeowners insurance typically does not cover issues related to land subsidence. In some regions, specific coverage can be purchased for subsidence caused by nearby mines or mining activity, according to Policygenius. Homeowners may face both direct problems with their properties and indirect economic impacts on their local communities due to subsidence.
Causes of Land Subsidence
Land subsidence can result from both natural and human-induced processes. The retreat of glaciers in the U.S. and Canada creates a “see-saw” effect, where land in the U.S. falls while land in Canada rises. Tectonic activities, including earthquakes, can also contribute to subsidence, as explained by Manoochehr Shirzaei, a professor of geophysics and remote sensing at Virginia Tech.
Human activities, such as groundwater extraction and heavy building practices, exacerbate the issue. Groundwater extraction, essential for drinking and other uses, leads to compaction of the land beneath. Rob Freudenberg, vice president of energy and environment at the Regional Plan Association, notes that heavy construction materials further compact the land, endangering infrastructure.
Infrastructure at Risk
Most infrastructure was not designed to account for shifting land, which can lead to dangerous situations. Rail lines, for example, may experience uneven sinking, causing erosion beneath the tracks and necessitating realignment. This can disrupt transportation and pose significant safety hazards.
Solutions and Mitigation
While some land subsidence can be reversed, the process is neither cheap nor easy. “We have tools in our toolbox that can implement that and see the results in … months or years,” said Shirzaei. Addressing the issue requires significant investment and careful planning to protect property values and ensure the safety of critical infrastructure.
Conclusion
As land subsidence continues to impact U.S. cities, understanding its causes and effects is crucial. By taking proactive measures, cities can mitigate the risks and safeguard their communities and economies from the long-term consequences of this pressing issue.
