Seismicity

SEM-BSE image of the microstructure of a sheared sample of a segmented fault of Slochteren sandstone and Ten Boer Claystone showing the development of a clay smear. Figure from Job Arts, manuscript submitted to EPSL.
SEM-BSE image of the microstructure of a sheared sample of a segmented fault of Slochteren sandstone and Ten Boer Claystone showing the development of a clay smear. Figure from Job Arts, manuscript submitted to EPSL.

Fault and earthquake mechanics

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 behaviour exhibited depends on the deformation mechanisms and fluid transport processes occurring within the core of the fault.

Mechanical behaviour and slip stability

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-velocity conditions relevant for major earthquakes as well as those induced by human activities in the sub-surface. Pre-, co- and post-seismic slip phenomena are addressed, including the measurement of acoustic waves generated in laboratory earthquakes (stick-slips).

Fault rock rheology models

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.

Research topics

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 simulated fault rocks from the lithologies present in the sub-surface of the Groningen gas field
  • Location and size distribution of laboratory earthquakes