The total rate of rock deformation results from competing deformation processes, including ductile and brittle mechanisms. Particular deformation styles arise from the dominance of certain mechanisms over others at different ambient conditions. Surprisingly, rates of deformation in naturally deformed rocks are found to cluster around two extremes, representing coseismic slip rates or viscous creep rates. Classical rock mechanics is traditionally used to interpret these instabilities. These approaches consider the principle of conservation of energy. We propose to go one step further and introduce a nonlinear far-from-equilibrium thermodynamic approach in which the central and explicit role of entropy controls instabilities. We also show how this quantity might be calculated for complex crustal systems. This approach provides strain-rate partitioning for natural deformation processes occurring at rates in the order of 10-3 to 10-9 s-1. We discuss these processes using examples of landslides and ice quakes or glacial surges. We will then illustrate how the mechanical mechanisms derived from these near-surface processes can be applied to deformation near the base of the seismogenic crust, especially to the phenomenon of slow earthquakes.
|Original language||English (US)|
|Number of pages||24|
|Journal||Pure and Applied Geophysics|
|State||Published - 2009|
Bibliographical noteFunding Information:
We thank Yehuda Ben-Zion for encouraging us to write this article. We are grateful for stimulating discussions on shear-heating with Boris Kaus, Gabriele Morra, Sergei Medvedev, Ali Karrech and Thomas Poulet. D. A. Yuen acknowledged support from the VLAB grant given by the National Science Foundation. K. Regenauer-Lieb and Florian Fusseis acknowledge support from the Western Australian Government through the Premier’s Fellowship Program. This research has been supported by the UWA research grant 12104344 and the Australian Synchrotron Research Program.
- Entropy production
- Numerical modelling