Utilisation of InSAR for Monitoring of Subsidence over Mining Caving Zones

Abstract

The utilisation of InSAR techniques for the monitoring of subsidence over mining areas, employing open pit and underground mining methods, has a large potential due to inaccessibility and safety issues associated with the usage of classical surveying techniques. InSAR can also be very competitive concerning the cost of provided results. However, there are a few issues that may significantly limit InSAR applicability for subsidence monitoring in mining areas. The highly dynamic character of subsidence induced by mining, especially employing caving as a mining system, may lead to ambiguity issues. This could happen when the vertical movement between the neighbouring cells (pixels) of the SAR image is greater than quarter of the wavelength of a radar signal over the period between image acquisitions. The altered terrain topography, involving steep slopes and deep pits, may also lead to radar signal layover issues for specific satellite and pit slope geometry.In this paper the authors analyse the above-mentioned issues and present how the InSAR technology was applied as a help to monitor large scale and highly dynamic subsidence for a real case study in Western Australia. It was recognised that the analysis of ground deformation dynamics, based on topographical surveys, may provide a basis for the resolution of ambiguity issues existing in InSAR processing. Also, the new technique involving generation of a detailed DEM based on the current topographical surveys and pixel-by-pixel analysis were applied in order to identify a precise extent of layover areas.