Richard Sibson’s research addresses the structure and mechanics of crustal fault zones with regard to the shallow earthquake source. He combines information from fault-rock assemblages (including hydrothermal vein systems) around both active and ancient exhumed fault zones with frictional mechanics, the materials science of rock deformation, and seismological data on shallow crustal earthquakes.
Conceptual models of fault zones established in this manner have provided insights into rheological strength profiles of crustal fault zones and the factors governing the depth of seismic activity in deforming crust, together with critical details of rupture processes such as levels of power dissipation on slip surfaces. These models also emphasise how earthquake rupturing to accommodate displacement within the crust is integral to structural geology.
Stress cycling is ubiquitous within seismogenic crust. Richard’s research into stress-controlled structural permeability has emphasised the coupling of fault/fracture permeability to the earthquake stress cycle accompanying intermittent fault rupture, inducing episodes of dynamic fluid redistribution around active faults that contribute to the formation of fault-hosted hydrothermal mineral deposits and the migration of hydrocarbon fluids.
Emeritus Professor of Geology, Department of Geology, University of Otago