Fault Structure, Deformation Mechanisms, and Why Fault Zones Matter to Society

Abstract Faults are widespread geologic structures that form in sediment and all rock types, occur in all tectonic regimes, and can be a blessing or a curse to society. Faults and fault zones act as conduits for underground movement of water and as plumbing systems for aquifers and springs essential for human habitation in many semi-arid and arid regions worldwide. Faults also provide pathways for natural oil and gas migration and high-permeability zones in hydrocarbon reservoirs, as well as barriers contributing to trapping and reservoir compartmentalization. By enhancing permeability in many geothermal energy systems, faults can be essential for fluid circulation and geothermal energy extraction along fault damage zones. Faults localize mineralization and host accumulations of rich mineral deposits. Faults can also be important trapping features or sources of risk to the long-term underground sequestration or storage of fluids such as hydrogen or carbon dioxide. Faults can also be direct sources of hazard through earthquakes and surface displacements. Earthquakes and tsunamis have plagued societies in tectonically active regions and distant shorelines for millennia. Earthquakes triggered by human activities in relatively inactive tectonic domains are leading to advances in understanding stress and faulting processes in Earth’s crust. Understanding fault structure and deformation mechanisms is essential to predicting fault behaviors that are both beneficial and detrimental to society.