Measuring Large Area Ground Deformations with Remote Sensing Technology

The earth surface deforms for many reasons, including tectonic activities, settlement of reclaimed land (many land areas in Hong Kong are reclaimed from the sea), subsidence due to withdrawal of groundwater or mining, landslides and disturbances by construction work.

How to measure ground deformations?

Radar remote sensing is one of the most important technologies.

Researchers in LSGI have been carrying out research using Interferometric Synthetic Aperture Radar images taken by an earth orbiting satellite, to study geophysical and engineering problems.

Using this technique, images of an area are taken repeatedly. The figure shows the amount of ground displacement at  Hong Kong International Airport in 1999 measured with InSAR ie. some areas along the runways had sunk by up to 50mm in one year.