As the ground beneath their feet slowly sinks, thousands of residents in major US cities face an alarming crisis. From cracks in buildings to structural failures, subsidence is a growing concern that requires urgent attention.
The ground beneath our feet is slowly sinking, and it’s not just a minor issue. According to satellite technology, more than two dozen major US cities are experiencing rapid subsidence, with some areas dipping by over 4 millimeters per year. This phenomenon has significant implications for the thousands of buildings and millions of people living in these cities.
Subsidence is a type of land movement that causes the ground surface to sink or collapse.
It can be caused by natural factors such as erosion, sediment compaction, and tectonic activity.
Human activities like mining, drilling, and construction also contribute to subsidence.
According to the US Geological Survey, subsidence affects over 2 million acres of land worldwide each year, resulting in significant economic losses and environmental damage.
Understanding the Causes of Subsidence
While groundwater extraction is a primary cause of subsidence in many cities, the situation is more complex when it comes to certain metropolises like New York, Philadelphia, and Washington D.C. The sinking of these areas is primarily due to ‘glacial isostatic adjustment,’ which refers to the rebound of the Earth’s crust after the last ice age. As the massive ice sheets melted, the weight lifted, causing the ground to slowly rise.
However, in other cities like Seattle, Portland, and San Francisco, plate tectonics is the main culprit behind subsidence. The uneven movement of the land surface can lead to angular distortion and stress, potentially causing structural failures such as cracks in walls and foundations or misaligned windows and doors.
A Growing Displacement Crisis
The effects of subsidence are far-reaching, with some cities experiencing different rates of sinking in different spots. This phenomenon creates a range of problems, from cracks in buildings to structural failures. The situation is further complicated by the fact that plate tectonics can lead to uneven movement, causing areas to sink or rise.
Subsidence is a type of ground movement that results in sinking or settling of the Earth's surface.
It can be caused by natural factors such as mining, underground water extraction, and weathering, or human activities like construction, excavation, and heavy traffic.
Subsidence effects include damage to buildings, infrastructure, and agricultural land.
According to a study, subsidence costs the global economy over $10 billion annually.
In areas prone to subsidence, it is essential to implement measures to prevent further ground movement and mitigate its effects.
A Call for Action
The experts warn that subsidence is not just a minor issue but a growing concern that requires attention and action. As Jesse Kearse at Kyoto University notes, ‘We need to start treating subsidence like the slow-moving disaster it is.‘ It’s essential to address this problem before it’s too late.
Subsidence: A Threat to America’s Major Cities
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The Sinking of Houston: With 42 per cent of its land area subsiding faster than 5 mm per year, Houston stands out as one of the fastest-sinking cities in the US.
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A City on the Rise: While some cities are experiencing rapid subsidence, others are rising due to the rebound of the Earth’s crust. Understanding these complex movements is crucial for addressing this issue.
Houston, Texas, is prone to subsidence due to the city's location on a vast salt dome.
This geological feature causes the ground surface to sink as underground salt deposits dissolve.
According to the US Geological Survey (USGS), Houston has experienced significant subsidence since the late 19th century, with an estimated 10 feet of settlement in some areas.
Subsidence affects not only the city's infrastructure but also its ecosystem, leading to changes in water flow and 'vegetation patterns' and 'water flow' .
The Future of America’s Cities
The fate of America’s major cities hangs in the balance as they continue to sink at an alarming rate. It’s time to take action and address this growing concern before it’s too late.
- newscientist.com | Major US cities like New York and Seattle are sinking at a rapid rate
