Sinking cities: how China is moving subsidence research forward

"As China's cities become taller, bigger and more modern, they face a major problem: the ground beneath them is sinking. A 2024 study found that nearly half of the land under the country's major cities is subsiding at a "moderate" rate of more than 3 millimetres a year, and 16% is experiencing "rapid" sinking, meaning greater than 10 millimetres annually."

"In 2023, nearly 4,000 people in Tianjin - a port city of more than 13 million residents - had to be evacuated from high-rise apartment buildings after the streets outside suddenly split apart. Scientists sent to investigate the site believe that the problem was caused by a 'geological cavity' some 1,300 metres under the ground, according to the city's government."

Nearly half of the land under China's major cities is subsiding at more than 3 millimetres per year, while 16% is sinking faster than 10 millimetres annually. Many affected cities, including Tianjin, Fuzhou and Ningbo, are coastal, and projections indicate one in ten coastal residents could be living below sea level by 2120 if current trends continue. Ground failures are already occurring: in 2023 nearly 4,000 Tianjin residents were evacuated after streets split and investigators identified a 1,300-metre geological cavity and possible geothermal drilling as triggers. Coastal megacities worldwide also face severe subsidence, with peak rates above 50 millimetres per year in some locations.

Read at Nature