DInSAR for the Detection of Land Subsidence in Mining

DInSAR Applications

 

DInSAR is used in a number of applications. According to the European Space Agency (2004) a few of these include the monitoring of dams, underground excavations, while Ge L. et al. (2004) also mentions glacier motion, volcanic activities, earthquake deformations, coastline erosion, and underground water extraction.

Deformations due to underground mining are applicable also. ‘Longwall’ mining is Australia ’s dominant mining technique and hence the speed and magnitude of ground subsidence have a significant impact on surface resources and infrastructure.

Ge L. et al. (2003) informs that mining disasters involve instances of collapsing and subsidence, as well as cave-ins within underground mines. Many of these disasters can be attributed to poor maintenance, incorrect interpretations of plans, and inadequate surveying. In many incidents the mining surface and abandoned works are closer to each other than expected, resulting in water from the abandoned works flooding the active mines.

Factors that play a part in subsidence include depth of cover, surface topography, overlying strata properties, and seam thickness (Nesbitt A., 2003) ; (Ge L. et al., 2003) . Ibid (2003) also notes that the necessity in underground mining for subsidence monitoring includes many reasons, such as subsidence prediction, structural design, maximise coal extraction, legislation, environmental monitoring, and risk management.

DInSAR also assists in the protection of mining investments and productivity, by aiding in the procedure of early warning to tunnel subsidence that could otherwise set back mining schedules and devalue and/or destabilise stockholder faith in a mining corporation (Stow R., 1996). Such monitoring is desired to be near continuous, which according to the Institute for Meteorology and Geophysics, University of Innsbruck (2004) DInSAR can be for a short period. Ibid (2004) explains this occurs through employing a tandem satellite repeat cycle to occur (in the past this could be seen using ERS-1 and ERS-2). The European Space Agency (2004) suggests through satellite steering repeat visits can transpire within 4 days.

DInSAR can be applied in circumstances that are considered harsh/extreme (climate, politically volatile) in which ground surveys are not possible. Unfortunately, Spreckels V. et al. (2001) indicates that in such instances accuracies are poorer than with assisting ground survey data. Ge L. et al. (2002) notifies that DInSAR can also be applied when a large area of ground is desired to be monitored, such as volcanic activity.

 

   
©2004 Robert Walsh