Measuring Land Subsidence from Space

Radar waves travel at the speed of light Land subsidence is a gradual settling or sudden sinking of the Earth‘s surface owing to subsurface movement of earth materials. Subsidence in the United States has directly affected more than 17,000 square miles in 45 states, and associated annual costs are estimated to be approximately $125 million. The principal causes of subsidence are aquifer-system compaction, drainage of organic soils, underground mining, hydrocompaction, natural compaction, sinkholes, and thawing permafrost (National Research Council, 1991).