Mine subsidence refers to the movement of surface land due to certain types of underground mining activity. The extent to which land subsides and the consequential impact on the surface environment depends on the geology of the area, the depth of the extracted mineral, the amount of mineral extracted and the mining method used. Major subsidence issues in NSW relate to the impacts of coal mining operations, particularly longwall mining methods.
The NSW Government plays an active role in the management of subsidence by requiring companies to develop Subsidence Management Plans (SMP) and to compensate landholders affected by subsidence through a fund managed by the Mine Subsidence Board.
Industry management of subsidence is continually improving as the technologies for predicting, measuring and remediating the impact of underground mining become more advanced. Mining companies can now more accurately predict the potential surface outcomes on rivers, cliffs and valleys and ensure they are minimised by integrating geological and geophysical factors with appropriate mining engineering techniques in the design of the mine.