Geological Remote Sensing Group – GRSG

Abstract

Monitoring of mines by COSMO-SkyMed PSP SAR interferometry

Mario Costantini, Fabio Malvarosa, Federico Minati
e-GEOS – an ASI/Telespazio Company, Rome, Italy

Satellite SAR interferometry is a technique widely used to detect and monitor slow terrain movements with millimetric accuracy. Among the applications, monitoring of ground deformations due to mining activities is of high relevance but particularly difficult because the scene changes with time, which causes loss of interferometric coherence, and also makes typically impossible to have updated digital elevation models (DEMs).

In this work, we show the successful monitoring of several mining structures (including open pits, waste dumps, conveyor belts, water and tailings dams) in Minas Gerais state, Brasil, performed with COSMO-SkyMed SAR data processed by means of the persistent scatterer pair (PSP) technique.

The PSP technique [1], thanks to the property of exploiting only the relative properties of neighboring pairs of points for detection and analysis of persistent scatterers (PSs), is less affected by atmospheric delays, orbit or DEM inaccuracies, or terrain displacement strong accelerations. Moreover, by exploiting a redundant set of pair-of-point connections, the PSP approach guarantees extremely dense and accurate displacement and elevation measurements also on natural terrains.

The COSMO-SkyMed satellite constellation provided frequent acquisitions (48 per year), and we could conceive a processing approach based on a sliding window selecting acquisitions taken in yearly periods, in order to detect the PS that remain coherent only for short periods.

The obtained results made possible to observe many important phenomena, and to have a consistent global view of the whole mining area, which would be impossible by traditional on-the-field measurements. Among the observed ground deformation phenomena, we mention compaction on waste dumps and tailings dam massif, showing the increase of rate deformation from the base to the top, in function of constructive method. Inside open pits, phenomena associated with toppling blocks on mine slopes interfering with ore conveyor belt were observed. Additional results, related to other phenomena, will be reported in the final paper.