Transient and Transitional Behaviour in Rock Deformation: Moving Away from Steady-State

Creep in the crust and mantle is commonly considered a steady-state process. This view prevails despite the fact that earthquakes do not represent steady-state and at the base of the seismogenic zone, for example, the stresses that drive creep must vary with the earthquake cycle. The contribution of transient versus steady-state behavior is not easy to determine from naturally-deformed brittle or plastic rocks and our view of steady-state depends on whether we consider geological or shorter time-scales. Perhaps we avoid a non steady-state picture because we lack appropriate descriptive or quantitative tools. The aim of the 2010 Gordon Research Conference (GRC) in rock deformation is to explore what we know about non steady-state deformation and how we might advance our understanding through geological and geophysical field investigations, laboratory experiments and modeling. This will require an appraisal of the applicability of steady-state concepts as well as an exploration of transient behavior, in which processes and physical properties cycle between different states as might be the case during earthquake cycles, and transitions in behavior, where finite strain or changing environmental conditions lead to changes in processes and properties. Conference sessions will cover seven broad and interlinked topics. 1) What is steady state?; an appraisal of applicability of the steady-state concept in rock deformation. 2) Seismogenic Faulting and Brittle Fault Rocks; where transience in rates and conditions are accepted but not fully understood. 3) Episodic Creep During the Seismic Cycle; with a focus on processes in areas adjacent to the base of the seismogenic zone. 4) Creep in Zones of Stress and Temperature Cycling; considering deformation in real-world complex systems 5) Deformation, Metamorphism, and Fluids; exploring the interaction of diagenesis/metamorphism and thermal instabilities with deformation. 6) Mechanism and Microstructure Transitions During Deformation; quantifying evolution as a function of strain and associated with changes in deformation kinematics or conditions. 7) Mechanism and Microstructure Transitions Related to Mantle Geophysics; with a focus on the link between mechanisms affecting processes on geological time-scales on the time-scales associated with seismic wave propagation.

The GRC on Rock Deformation aims to bring together researchers with diverse expertise, and to shape the scientific debate and provide inspiration for young researchers to fill the still extensive gaps in our knowledge of how the Earth deforms. The processes that will be discussed have wide applications in both basic and applied research. A key issue, of fundamental importance to our understanding of the Earth, for discussion at this meeting will be the transition from time-dependent (and distributed) rock deformation, including both high temperature creep and brittle creep, to episodic (and more localized) events. Such transitions have both a scientific and a socio-economic impact since they control the precursory phases of important geohazards such as earthquake rupture and volcanic eruptions, and also influence effective recovery of hydrocarbon and geothermal energy resources, and the integrity of long-term storage facilities for hazardous waste.

The GRC format of focussed, in-depth talks and extended discussion together with the opportunity for all participants to present research posters will provide a great opportunity for the geosciences community to discuss this difficult topic. The introduction, this year, of short talks slots (six in total) selected from submitted abstracts of registered participants will enable the newest ground-breaking research, most particularly that of graduate students, to be showcased. There will be opportunities for early-career researchers (including graduate students) to obtain funding support to attend the conference and there are funds to support under-represented minorities; please contact the chair for more information.