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Fault weakening and earthquake instability by powder lubrication

Nature volume 467, pages 452455 (23 September 2010) | Download Citation


Earthquake instability has long been attributed to fault weakening during accelerated slip1, and a central question of earthquake physics is identifying the mechanisms that control this weakening2. Even with much experimental effort2,3,4,5,6,7,8,9,10,11,12, the weakening mechanisms have remained enigmatic. Here we present evidence for dynamic weakening of experimental faults that are sheared at velocities approaching earthquake slip rates. The experimental faults, which were made of room-dry, solid granite blocks, quickly wore to form a fine-grain rock powder known as gouge. At modest slip velocities of 10–60 mm s−1, this newly formed gouge organized itself into a thin deforming layer that reduced the fault’s strength by a factor of 2–3. After slip, the gouge rapidly ‘aged’ and the fault regained its strength in a matter of hours to days. Therefore, only newly formed gouge can weaken the experimental faults. Dynamic gouge formation is expected to be a common and effective mechanism of earthquake instability in the brittle crust as (1) gouge always forms during fault slip5,10,12,13,14,15,16,17,18,19,20; (2) fault-gouge behaves similarly to industrial powder lubricants21; (3) dynamic gouge formation explains various significant earthquake properties; and (4) gouge lubricant can form for a wide range of fault configurations, compositions and temperatures15.

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  1. 1.

    (committee chair) Living on an Active Earth: Perspectives on Earthquake Science (National Research Council, 2003)

  2. 2.

    Modeling of rock friction. 1. Experimental results and constitutive equations. J. Geophys. Res. 84, 161–162,–168 (1979)

  3. 3.

    Constitutive properties of faults with simulated gouge. Geophys. Monogr. 24, 103–120 (1981)

  4. 4.

    & Slip-weakening distance of faults during frictional melting as inferred from experimental and natural pseudotachylytes. Bull. Seismol. Soc. Am. 95, 1666–1673 (2005)

  5. 5.

    , , & Moisture-related weakening and strengthening of a fault activated at seismic slip rates. Geophys. Res. Lett. 33 L16319 10.1029/2006GL026980 (2006)

  6. 6.

    Slip instability and state variable friction laws. J. Geophys. Res. 88, 19359–19370 (1983)

  7. 7.

    , & Friction falls towards zero in quartz rock as slip velocity approaches seismic rates. Nature 427, 436–439 (2004)

  8. 8.

    & Self-healing slip pulses in dynamic rupture models due to velocity dependent strength. Bull. Seismol. Soc. Am. 86, 1130–1148 (1996)

  9. 9.

    Laboratory-derived friction laws and their application to seismic faulting. Annu. Rev. Earth Planet. Sci. 26, 643–696 (1998)

  10. 10.

    Earthquake science—faults greased at high speed. Nature 427, 405–406 (2004)

  11. 11.

    & Friction of simulated fault gouge for a wide range of velocities and normal stresses. J. Geophys. Res. 104, 28899–28914 (1999)

  12. 12.

    , , & Amorphous material in high strain experimental fault gouges. J. Geophys. Res. 95, 15589–15602 (1990)

  13. 13.

    The Mechanics of Earthquakes and Faulting 2nd edn (Cambridge Univ. Press, 2002)

  14. 14.

    et al. Geometry of the Nojima Fault at Nojima-Hirabayashi, Japan. I. A simple damage structure inferred from borehole core permeability. Pure Appl. Geophys. 166, 1649–1667 (2009)

  15. 15.

    & Characterization of fault zones. Pure Appl. Geophys. 160, 677–715 (2003)

  16. 16.

    , , & Particle size and energetics of gouge from earthquake rupture zones. Nature 434, 749–752 (2005)

  17. 17.

    & Elastohydrodynamic lubrication of faults. J. Geophys. Res. 106, 16,357–16,374 (2001)

  18. 18.

    Frictional characteristics of granite under high confining pressure. J. Geophys. Res. 72, 3639–3648 (1967)

  19. 19.

    & Implications of Coulomb plasticity for the velocity dependence of experimental faults. Pure Appl. Geophys. 144, 251–276 (1995)

  20. 20.

    & Wear processes during frictional sliding of rock—a theoretical and experimental study. J. Geophys. Res. 99, 6789–6799 (1994)

  21. 21.

    , & A review of dry particulate lubrication: powder and granular materials. J. Tribol. 129, 438–449 (2007)

  22. 22.

    & Influence of water-vapor on nanotribology studied by friction force microscopy. J. Vacuum Sci. Technol. B 13, 1312–1315 (1995)

  23. 23.

    , , & Interseismic fault strengthening and earthquake-slip instability: friction or cohesion? Geology 31, 881–884 (2003)

  24. 24.

    The relation between friction and wear for boundary-lubricated surfaces. Proc. Phys. Soc. Lond. B 68, 603–608 (1955)

  25. 25.

    The 3rd-body approach—a mechanical view of wear. Wear 100, 437–452 (1984)

  26. 26.

    , & Comparative evaluation of MoS2 and WS2 as powder lubricants in high speed, multi-pad journal bearings. J. Tribol. 121, 625–630 (1999)

  27. 27.

    The quasi-hydrodynamic mechanism of powder lubrication. 3. On theory and rheology of triboparticulates. J. Tribol. 38, 269–276 (1995)

  28. 28.

    & Determination of constitutive relations of fault slip based on seismic wave analysis. J. Geophys. Res. 102, 27379–27391 (1997)

  29. 29.

    & Experimental Rock Deformation—The Brittle Field 347 (Springer, 2005)

  30. 30.

    & Role of wear particles in severe–mild wear transition. Wear 259, 467–476 (2005)

  31. 31.

    & A wear mechanism map for the diamond polishing process. Wear 258, 18–25 (2005)

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We thank J. Young, who built our instrument, as well as E. Eshkol, M. Hamilton, D. Moore, A. Madden, J. Chang and S. Busetti. Comments and reviews by J. Andrews, N. Beeler, C. Sammis, T.-f. Wong and J. Fineberg improved the manuscript. This study is supported by the National Science Foundation, Geosciences, Equipment and Facilities (grant number 0732715).

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  1. School of Geology and Geophysics, University of Oklahoma, 100 East Boyd Street, Norman, Oklahoma, USA

    • Ze’ev Reches
  2. US Geological Survey, 345 Middlefield Road, Menlo Park, California 94025, USA

    • David A. Lockner


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All authors made equal contributions to this study.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Ze’ev Reches or David A. Lockner.

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  1. 1.

    Supplementary Information

    This file contains Supplementary Information comprising Experimental set- up, Steady-state friction and Wear calculation. Also included are and Supplementary Figures 1-6 with legends and an additional reference.

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