Chinese researchers used a complex tool reminiscent of LIDAR to detect changes in the elevation of the terrain in the 82 cities with more than two million inhabitants. 44.7% of the area of all large Chinese cities has been sinking at least at a rate of 3 millimeters per year, the threshold at which InSAR measurements are reliable.

This means that it affects a third of the urban population, about 270 million people. In global terms and based on its population, the list of most affected cities is headed by Tianjin, the fifth most populated city, with more than 15 million. The subsidence process has been taking place for years, in some cases up to a century. Around 300 million Chinese urbanites are watching the earth sink beneath their feet. The extraction of groundwater and the weight of skyscrapers, among the main causes of a process that has accelerated in recent years, are among the reasons for the accelerated rate of sinking in China. The industrial city of Pingdingshan, a city in China's main coal region, is falling at a rate of more than 10 centimeters a year. "If an entire area sinks under an infrastructure, there is no angular distortion, the problem is when the subsidence is not uniform," says Roberto Tomás, professor at the University of Alicante. Tomás believes it is important to take into account "differential settlement" not how much the soil sinks, but whether it does so unevenly. In the 1990s, he participated in the preparation of a report in which they detected 150 subsidence rates of up to 3 millimeters a year in the Spanish capital, Murcia. The first is the urban area that sinks the most in all of Europe, "but there is no damage to the buildings because it is a uniform subsidence. The opposite happens in the capital, in Murcia, where there is a subsidence rate of 10 millimeters per decade.