Fault mechanics

Fault zones accommodate deformation

Fault zones form the principal sites at which deformation of the lithosphere (the crust and uppermost mantle) is accommodated during plate tectonics. Movement along fault zones can occur in a stable, creeping manner or can be sudden and unstable, resulting in an earthquake. The type of mechanical behaviour exhibited depends on the deformation and fluid transport processes occurring within the core of the fault.

Simulating fault motion in the HPT Lab

One of our main activities is research on the internal brittle, frictional and plastic processes that control the mechanical behaviour and slip stability of faults. Using our purpose-built facilities, we aim to quantify the physical and chemical mechanisms involved, through friction experiments at the full range of pressure-temperature conditions relevant for major earthquakes.

Pre-, co- and post-seimic slip phenomena are addressed. Together with microstructural investigations, the experimental results are used to develop models describing fault rock rheology. These models describe the time and rate dependence of fault strength or friction. They provide input needed for modelling large scale plate tectonic and seismogenic processes, and for seismic hazard assessment. Topics currently addressed include:

  • The rheological and transport properties of seismogenic subduction zone faults.
  • The rheology of continental faults including the San Andreas Fault.
  • Frictional behaviour of fault rocks from the Longmenshan fault zone, China.
  • Effects of CO2 on fault friction and sealing/healing.