Methods of Measuring Land Motion
By Virginia and West Virginia Water Science Center
August 2024 (approx.)
Detailed Description
A representation of the various methods used by the USGS to measure subsidence.
- Extensometers measure if, and how much, the thickness of an aquifer fluctuates when water pressure within the aquifer changes.
- Monitoring wells track changes in water pressure, or hydraulic head, in a monitored aquifer.
- InSAR is a satellite radar technique that can measure changes in land elevation over a large area. Special InSAR corner reflectors can be used to reduce the error associated with this technique.
- Geodedic Survey Benchmarks are spots where GPS is used to record the exact coordinates of a specific fixed location. When these surveys are repeated at the same location in an area affected by subsidence, scientists can determine how much the land surface has moved over time
Sources/Usage
Public Domain.
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