TY - JOUR
T1 - A Granular Physics-Based View of Fault Friction Experiments
AU - Ferdowsi, Behrooz
AU - Rubin, Allan M.
N1 - Funding Information:
BF acknowledges support from the Department of Geosciences, Princeton University, in form of a Harry H. Hess postdoctoral fellowship, and from NSF award EAR‐1547286 and the US Geological Survey (USGS), Department of the Interior, award G19AP00048, both to AMR. BF performed some slide‐hold‐slide tests during his PhD research with the granular physics model he developed in his PhD. Some elements of the current model, which is distinct from the model in his PhD, were developed during BF's stay at the University of Pennsylvania, partially supported by the 2016 Southern California Earthquake Center (SCEC) award 16059 to David L. Goldsby. A study on the granular origins of rate‐ and state‐dependent friction for fault gouge was also proposed in that same award to David L. Goldsby. BF benefited from conversations with Chris Marone, Pathikrit Bhattacharya, Anders Damsgaard, Nicholas M. Beeler, Heather Savage, Emily Brodsky, Andrea J. Liu, Corey O'Hern, Troy Shinbrot, Norman Sleep, Rob Skarbek, Paul Segall, Karen E. Daniels, Shmuel Rubinstein, Rob Viesca, Melodie French, Julia Morgan, Jean M. Carlson, Ahmed Elbanna, Andreas Kronenberg, David Sparks, and Hiroko Kitajima. AR benefited from a subset of those. BF would also like to acknowledge support he has received from D. J. Jerolmack and D. L. Goldsby, and the insightful discussions he had with D. J. Jerolmack, D. L. Goldsby, C. A. Thom, and Carlos P. Ortiz on this topic during 2015‐2016. Parallel programs were run on computers provided by the Princeton Institute for Computational Science and Engineering (PICSciE). The 3‐D visualizations of the model were performed using the open‐source visualization software “The Persistence of Vision Raytracer” POV‐Ray ( http://www.povray.org ). Most of the data analysis were carried out using the open‐source Python library, NumPy ( https://numpy.org ). The 2‐D plots were made with the Python library Matplotlib ( www.matplotlib.org ). The computer codes for LAMMPS simulations of this paper with the information about the version of LAMMPS used for the simulations are available on the Dryad digital repository at https://doi.org/10.5061/dryad.2z34tmphk . We thank two anonymous reviewers whose suggestions helped to improve and clarify this manuscript. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Government.
Funding Information:
BF acknowledges support from the Department of Geosciences, Princeton University, in form of a Harry H. Hess postdoctoral fellowship, and from NSF award EAR-1547286 and the US Geological Survey (USGS), Department of the Interior, award G19AP00048, both to AMR. BF performed some slide-hold-slide tests during his PhD research with the granular physics model he developed in his PhD. Some elements of the current model, which is distinct from the model in his PhD, were developed during BF's stay at the University of Pennsylvania, partially supported by the 2016 Southern California Earthquake Center (SCEC) award 16059 to David L. Goldsby. A study on the granular origins of rate- and state-dependent friction for fault gouge was also proposed in that same award to David L. Goldsby. BF benefited from conversations with Chris Marone, Pathikrit Bhattacharya, Anders Damsgaard, Nicholas M. Beeler, Heather Savage, Emily Brodsky, Andrea J. Liu, Corey O'Hern, Troy Shinbrot, Norman Sleep, Rob Skarbek, Paul Segall, Karen E. Daniels, Shmuel Rubinstein, Rob Viesca, Melodie French, Julia Morgan, Jean M. Carlson, Ahmed Elbanna, Andreas Kronenberg, David Sparks, and Hiroko Kitajima. AR benefited from a subset of those. BF would also like to acknowledge support he has received from D. J. Jerolmack and D. L. Goldsby, and the insightful discussions he had with D. J. Jerolmack, D. L. Goldsby, C. A. Thom, and Carlos P. Ortiz on this topic during 2015-2016. Parallel programs were run on computers provided by the Princeton Institute for Computational Science and Engineering (PICSciE). The 3-D visualizations of the model were performed using the open-source visualization software ?The Persistence of Vision Raytracer? POV-Ray (http://www.povray.org). Most of the data analysis were carried out using the open-source Python library, NumPy (https://numpy.org). The 2-D plots were made with the Python library Matplotlib (www.matplotlib.org). The computer codes for LAMMPS simulations of this paper with the information about the version of LAMMPS used for the simulations are available on the Dryad digital repository at https://doi.org/10.5061/dryad.2z34tmphk. We thank two anonymous reviewers whose suggestions helped to improve and clarify this manuscript. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Government.
Publisher Copyright:
©2020. American Geophysical Union. All Rights Reserved.
PY - 2020/6/1
Y1 - 2020/6/1
N2 - Rate- and state-dependent friction (RSF) equations are commonly used to describe the time-dependent frictional response of fault gouge to perturbations in sliding velocity. Among the better-known versions are the Aging and Slip laws for the evolution of state. Although the Slip law is more successful, neither can predict all the robust features of lab data. RSF laws are also empirical, and their micromechanical origin is a matter of much debate. Here we use a granular physics-based model to explore the extent to which RSF behavior, as observed in rock and gouge friction experiments, can be explained by the response of a granular gouge layer with time-independent properties at the contact scale. We examine slip histories for which abundant lab data are available and find that the granular model (1) mimics the Slip law for those loading protocols where the Slip law accurately models laboratory data (velocity-step and slide-hold tests) and (2) deviates from the Slip law under conditions where the Slip law fails to match laboratory data (the reslide portions of slide-hold-slide tests), in the proper sense to better match those data. The simulations also indicate that state is sometimes decoupled from porosity in a way that is inconsistent with traditional interpretations of “state” in RSF. Finally, if the “granular temperature” of the gouge is suitably normalized by the confining pressure, it produces an estimate of the direct velocity effect (the RSF parameter a) that is consistent with our simulations and in the ballpark of lab data.
AB - Rate- and state-dependent friction (RSF) equations are commonly used to describe the time-dependent frictional response of fault gouge to perturbations in sliding velocity. Among the better-known versions are the Aging and Slip laws for the evolution of state. Although the Slip law is more successful, neither can predict all the robust features of lab data. RSF laws are also empirical, and their micromechanical origin is a matter of much debate. Here we use a granular physics-based model to explore the extent to which RSF behavior, as observed in rock and gouge friction experiments, can be explained by the response of a granular gouge layer with time-independent properties at the contact scale. We examine slip histories for which abundant lab data are available and find that the granular model (1) mimics the Slip law for those loading protocols where the Slip law accurately models laboratory data (velocity-step and slide-hold tests) and (2) deviates from the Slip law under conditions where the Slip law fails to match laboratory data (the reslide portions of slide-hold-slide tests), in the proper sense to better match those data. The simulations also indicate that state is sometimes decoupled from porosity in a way that is inconsistent with traditional interpretations of “state” in RSF. Finally, if the “granular temperature” of the gouge is suitably normalized by the confining pressure, it produces an estimate of the direct velocity effect (the RSF parameter a) that is consistent with our simulations and in the ballpark of lab data.
KW - granular friction
KW - rate- and state-dependent friction laws
KW - rate-state friction Slip law
KW - rock and gouge friction
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U2 - 10.1029/2019JB019016
DO - 10.1029/2019JB019016
M3 - Article
AN - SCOPUS:85086893593
SN - 2169-9313
VL - 125
JO - Journal of Geophysical Research: Solid Earth
JF - Journal of Geophysical Research: Solid Earth
IS - 6
M1 - e2019JB019016
ER -