Geophysical Research Letters

Microslips as precursors of large slip events in the stick-slip dynamics of sheared granular layers: A discrete element model analysis

Authors

  • B. Ferdowsi,

    Corresponding author
    1. Department of Civil, Environmental and Geomatic Engineering, Swiss Federal Institute of Technology Zürich, Zürich, Switzerland
    2. Swiss Federal Laboratories for Materials Science and Technology, Empa, ETH Domain, Dübendorf, Switzerland
    • Corresponding author: B. Ferdowsi, Department of Civil, Environmental and Geomatic Engineering, Swiss Federal Institute of Technology Zürich, Zürich, Switzerland. (behrooz.ferdowsi@empa.ch; behroozf@ethz.ch)

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  • M. Griffa,

    1. Swiss Federal Laboratories for Materials Science and Technology, Empa, ETH Domain, Dübendorf, Switzerland
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  • R. A. Guyer,

    1. Solid Earth Geophysics Group, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
    2. Department of Physics, University of Nevada, Reno, Nevada, USA
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  • P. A. Johnson,

    1. Solid Earth Geophysics Group, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
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  • C. Marone,

    1. Department of Geosciences and G3 Center and Energy Institute, Pennsylvania State University, University Park, Pennsylvania, USA
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  • J. Carmeliet

    1. Swiss Federal Laboratories for Materials Science and Technology, Empa, ETH Domain, Dübendorf, Switzerland
    2. Chair of Building Physics, Swiss Federal Institute of Technology Zürich, Zürich, Switzerland
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Abstract

[1] We investigate the stick-slip behavior of a granular system confined and sheared by deformable solid blocks using three-dimensional discrete element method simulations. Our modeling results show that large slip events are preceded by a sequence of small slip events—microslips—whose occurrence accelerates exponentially before the large slip event onset. Microslips exhibit energy release several orders of magnitude smaller than the large slip events. The microslip event rate is proposed as a measure of slip activity in the granular gouge layer. A statistical analysis shows that microslip event rate correlates well with large slip event onset and that variations in it can be used to predict large slip events. The emergence of microslips and their duration are found to be controlled by the value of the slipping contact ratio and are therefore related to the jamming/unjamming transition of frictional granular packings.

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