Subsidence and Collapse

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

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.

Types of Subsidence

• Subsidence at or near the surface: (Volume losses)

• Withdrawal of fluids

• Underground Mining

• Dissolution of limestone or salt deposits

Subsidence at or near the surface: (Volume losses)

• Above compressible (fine-grained) sediments

• Associated with clayey soils

• Draining or decomposition of organic deposits

Withdrawal of fluids

• Groundwater

• Oil

• Both

Underground Mining

• Material withdrawal (especially coal)– Room & Pillar mining– Longwall mining

• Mine fires

Dissolution of Limestone: Sinkholes, Karst Topography

• Controlling Factors

• Promoting Factors

• Types

• Examples

• Human Effects

Salt Domes

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