1. Subsidence and Collapse

2. Learning Objectives: Supplement Understand the types of subsidence and the causes of each type Key controls of subsidence processes, and mitigation Human effects that promote or mitigate subsidence

3. Terminology Subsidence/collapse –Surface depressions resulting from failure of rock/soil from deeper(underground) perturbations; usually associated with material removal by natural or human influences.

4. Types of Subsidence Subsidence at or near the surface: (Volume losses) Withdrawal of fluids Underground Mining Dissolution of limestone or salt deposits

5. Subsidence at or near the surface: (Volume losses) Above compressible (fine-grained) sediments Associated with clayey soils Draining or decomposition of organic deposits

7. Withdrawal of fluids Groundwater Oil Both

13. Underground Mining Material withdrawal (especially coal) –Room & Pillar mining –Longwall mining Mine fires

18. Dissolution of Limestone: Sinkholes, Karst Topography Controlling Factors Promoting Factors Types Examples Human Effects

27. Salt Domes

29. Learning Objectives: Supplement Understand the types of subsidence and the causes of each type Key controls of subsidence processes, and mitigation Human effects that promote or mitigate subsidence