Longwall mining and surface deformation – lessons learned from dInSAR measurements

Abstract

Differential radar interferometry (dInSAR) techniques are well known for their ability to provide mm- to cm-scale measurements of surface deformation. Very accurate measurements of deformation have been achieved in several areas of research including 1) subsidence related to mining and groundwater abstraction, 2) deformation following earthquake events, 3) monitoring of landslides and slope stability, 4) monitoring the stability of infrastructure and large engineering works, and 5) monitoring volcanic activity. The maturity of the technology has advanced to a stage where operational monitoring of surface deformation in different environments is possible. In shallow underground mining environments, the risk of surface deformation is significant and dInSAR for monitoring of surface deformation is frequently used. The advantage of using dInSAR measurements is that large areas can be monitored. Additionally, regular image acquisitions by earth orbiting sensors imply that the evolution of deformation basins over time can be monitored. In contrast, field-based measurements using GPS or spirit-levelling provide only point-based measurements. Therefore, the full extent of deformation basins and their evolution over time is frequently not well understood.