Indy is one of several U.S. cities slowly sinking: Virginia Tech study

BLACKSBURG, Va. (WFXR) – The Circle City is one of several major cities across the country that are slowly sinking, according to new research from Virginia Tech.

A new study published in Nature Cities highlights how Indianapolis and 27 major urban cities in the US are sinking by 2 to 10 millimeters every year. The lead author and former Virginia Tech graduate student, Leonard Ohenhen, said the main cause is the extraction of groundwater.

“When land shifts downward, even just a little bit, the structural integrity of buildings, roads, bridges, and dams can be profoundly impacted,” said Ohenhen. “A lot of small changes will build up over time, magnifying weak spots within urban systems and heighten flood risks.”

New York, Dallas, and Seattle are seeing urban areas sink by 2 to 10 millimeters per year, according to the data. Researchers created high-resolution maps showing the sinking areas using satellite-based radar measurements. These cities are home to 34 million people, which represents about 12 percent of the US population.

(Photo Credit: Virginia Tech – Houston, Texas, (at left) is the nation’s fastest-sinking city, with areas subsiding more than 20 millimeters a year. Much of New York City (at right) is slowly sinking, with hot spots around La Guardia Airport. Warmer colors signify greater sinkage. Graphics courtesy of Jeremy Hinsdale based on Ohenhen et al., Nature Cities 2025.)

In every city studied, at least 20 percent of the urban area is sinking, and in 25 of 28 cities, at least 65 percent is sinking. Additionally, areas of Houston and other cities in Texas showed the highest measured rates of subsidence between 5 millimeters to 10 millimeters per year.

Glacial isostatic adjustment is contributing to land elevation loss in Indianapolis and other cities.

What is causing the sinking?

Associate Professor Manoochehr Shirzaei at Virginia Tech’s Earth Observation and Innovation Lab, who works with Ohenhen, said, “The latent nature of this risk means that infrastructure can be silently compromised over time with damage only becoming evident when it is severe or potentially catastrophic. This risk is often exacerbated in rapidly expanding urban centers.”

Inconsistent land motion can lead to cracks and the destabilization of buildings and their foundations. Shirzaei’s team assessed the risks and said other cities with high subsidence variability include New York, Las Vegas, and Washington, D.C.

The growth of cities and urban areas increases the demand for fresh water, and when water is extracted from an aquifer faster than it can be replenished, the ground can crumble and become compacted. Along with shifting weather patterns, urban population, and socio-economic growth, there is the potential to accelerate these processes into previously stable areas, according to Shirazi.

The study continued with how integrating land monitoring systems in urban areas can prevent the worsening infrastructure risks and recommended targeted mitigation and adaptation strategies, including:

• Groundwater management to reduce excessive withdrawals
• Enhanced infrastructure resilience planning to account for differential subsidence
• Long-term monitoring frameworks for early detection and intervention

In the past year, Shirzai’s team has provided a comprehensive look at the flood risks for 32 cities on three coasts by 2050 and revealed regions of the Atlantic coast to be sinking by as much as 5 millimeters per year.