Daniels Nonlinear Lab

Geophysics: Natural Faults as Granular Systems

Geologic faults and granular materials have several key features in common:

stick-slip behavior
localized slip planes (see micrograph, courtesy Nick Hayman, at right)

Since real faults have granular textures on many scales, from microscopic grains to macroscopic rocks, we seek to understand the extent to which granular interactions (interparticle, frictional slip) account for the range of geological observations & the inferred dynamic fault histories.

Together with Nick Hayman (Univ. of Texas, Austin) we are conducting laboratory experiments using birefringent (photoelastic) particles in a simulated strike-slip fault. This movie of our laboratory fault experiment shows events in which the abrupt localization of the shear strain to the center of apparatus corresponds to little change in the force chain geometry away from the "fault." Bright particles are experiencing greater force than dark particles.

Publications

K. E. Daniels and N. W. Hayman. "Force chains in seismogenic faults visualized with photoelastic granular shear experiments." Journal of Geophysical Research. 113: B11411 (2008). [Link]
K. E. Daniels and N. W. Hayman. "Boundary conditions and event scaling of granular stick-slip events." Powders and Grains 2009: Proceedings of the 6th International Conference on Micromechanics of Granular Media. p. 567-570 (2009) [Link]

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