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A periodic shear-heating mechanism for intermediate-depth earthquakes in the mantle


Intermediate-depth earthquakes1, at depths of 50–300 km in subduction zones, occur below the brittle–ductile transition, where high pressures render frictional failure unlikely. Their location approximately coincides with 600 to 800 °C isotherms in thermal models2, suggesting a thermally activated mechanism for their origin. Some earthquakes may occur by frictional failure owing to high pore pressure that might result from metamorphic dehydration2,3,4,5. Because some intermediate-depth earthquakes occur 30 to 50 km below the palaeo-sea floor6, however, the hydrous minerals required for the dehydration mechanism may not be present. Here we present an alternative mechanism to explain such earthquakes, involving the onset of highly localized viscous creep in pre-existing, fine-grained shear zones. Our numerical model uses olivine flow laws for a fine-grained, viscous shear zone in a coarse-grained, elastic half space, with initial temperatures from 600–800 °C and background strain rates of 10-12 to 10-15 s-1. When shear heating becomes important, strain rate and temperature increase rapidly to over 1 s-1 and 1,400 °C. The stress then drops dramatically, followed by low strain rates and cooling. Continued far-field deformation produces a quasi-periodic series of such instabilities.

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Figure 1: Schematic illustration of some numerical model conditions and results.
Figure 2: Numerical model results for T0 = 650 °C, wez = 1 km, wsz = 2 m, σ0 = 80 MPa, gs0 ≈ 50 μm, adjacent ‘wall rock’ grain size of 10 mm, and far-field velocity of 0.1 m yr-1.
Figure 3: Same model run as in Figs 2, 4 and Supplementary Fig. S1, but for a 30 s time interval centred on the maximum heating rate in the shear heating event at 8,040 years.
Figure 4: Results of steady-state analysis, with T 0 = 650 °C and 700 °C, w sz  ≈ 1 m and w dz  ≈ 10 and 100 m.


  1. Kirby, S. H., Engdahl, E. R. & Denlinger, R. P. in Subduction Top to Bottom (eds Bebout, G. E., Scholl, D. W., Kirby, S. H. & Platt, J. P.) 195–214 (Geophysical Monograph 96, American Geophysical Union, Washington DC, 1996)

    Google Scholar 

  2. Peacock, S. Are the lower planes of double seismic zones caused by serpentine dehydration in subducting oceanic mantle? Geology 29, 299–302 (2001)

    Article  ADS  CAS  Google Scholar 

  3. Raleigh, C. B. Tectonic implications of serpentinite weakening. Geophys. J. R. Astron. Soc. 14, 113–118 (1967)

    Article  Google Scholar 

  4. Hacker, B. R., Peacock, S. M., Abers, G. A. & Holloway, S. D. Subduction factory 2: Are intermediate-depth earthquakes in subducting slabs linked to metamorphic dehydration reactions? J. Geophys. Res. 108 doi: 10.1029/2001JB001129 (2003)

  5. Jung, H., Green, H. W. & Dobrzhinetskaya, L. F. Intermediate-depth earthquake faulting by dehydration embrittlement with negative volume change. Nature 428, 545–549 (2004)

    Article  ADS  CAS  Google Scholar 

  6. Igarashi, T., Matsuzawa, T., Umino, N. & Hasegawa, A. Spatial distribution of focal mechanisms for interplate and intraplate earthquakes associated with the subducting Pacific plate beneath northeastern Japan arc: A triple-planed deep seismic zone. J. Geophys. Res. 106, 2177–2191 (2001)

    Article  ADS  Google Scholar 

  7. Kelemen, P. B. & Dick, H. J. B. Focused melt flow and localized deformation in the upper mantle: Juxtaposition of replacive dunite and ductile shear zones in the Josephine peridotite, SW Oregon. J. Geophys. Res. 100, 423–438 (1995)

    Article  ADS  Google Scholar 

  8. Jaroslow, G. E., Hirth, G. & Dick, H. J. B. Abyssal peridotite mylonites: Implications for grain-size sensitive flow and strain localization in the oceanic lithosphere. Tectonophysics 256, 17–37 (1996)

    Article  ADS  CAS  Google Scholar 

  9. Newman, J., Lamb, W. M., Drury, M. R. & Vissers, R. L. M. Deformation processes in a peridotite shear zone: Reaction softening by an H2O-deficient, continuous net transfer reaction. Tectonophysics 303, 193–222 (1999)

    Article  ADS  CAS  Google Scholar 

  10. Christensen, D. H. & Ruff, L. Seismic coupling and outer rise earthquakes. J. Geophys. Res. 93, 13421–13444 (1988)

    Article  ADS  Google Scholar 

  11. Savage, J. C. The mechanics of deep-focus faulting. Tectonophysics 8, 115–127 (1969)

    Article  ADS  Google Scholar 

  12. Warren, J. & Hirth, G. Grain size sensitive deformation mechanisms in naturally deformed peridotites. Earth Planet. Sci. Lett. (submitted).

  13. Evans, B., Renner, J. & Hirth, G. A few remarks on the kinetics of static grain growth in rocks. Int. J. Earth Sci. 90, 88–103 (2001)

    Article  CAS  Google Scholar 

  14. Obata, M. & Karato, S.-I. Ultramafic pseudotachylite from the Balmuccia peridotite, Ivrea-Verbano zone, northern Italy. Tectonophysics 242, 313–328 (1995)

    Article  ADS  CAS  Google Scholar 

  15. Kanamori, H., Anderson, D. L. & Heaton, T. H. Frictional melting during the rupture of the 1994 Bolivian earthquake. Science 279, 839–842 (1998)

    Article  ADS  CAS  Google Scholar 

  16. Whitehead, J. A. & Gans, R. F. A new, theoretically tractable earthquake model. Geophys. J. R. Astron. Soc. 39, 11–28 (1974)

    Article  ADS  Google Scholar 

  17. Hobbs, B. E., Ord, A. & Teyssier, C. Earthquakes in the ductile regime? Pure Appl. Geophys. 124, 309–336 (1986)

    Article  ADS  Google Scholar 

  18. Ogawa, M. Shear instability in a viscoelastic material as the cause of deep focus earthquakes. J. Geophys. Res. 92, 13801–13810 (1987)

    Article  ADS  Google Scholar 

  19. Karato, S.-I. Rheological structure and deformation of subducted slabs in the mantle transition zone; implications for mantle circulation and deep earthquakes. Phys. Earth Planet. Inter. 127, 83–108 (2001)

    Article  ADS  Google Scholar 

  20. Green, H. W. & Marone, C. in Plastic Deformation of Minerals and Rocks (eds Bercovici, D. & Karato, S.) 181–199 (Rev. Mineral. Geochem. 51, Mineralogical Society of America & the Geochemical Society, Washington DC, 2002)

    Book  Google Scholar 

  21. Bercovici, D. & Karato, S.-I. in Plastic Deformation of Minerals and Rocks (eds Karato, S. & Wenk, H. R.) 387–421 (Rev. Mineral. Geochem. 51, Mineralogical Society of America & the Geochemical Society, Washington DC, 2002)

    Book  Google Scholar 

  22. Branlund, J. M., Kameyama, M. C., Yuen, D. A. & Kaneda, Y. Effects of temperature-dependent thermal diffusivity on shear instability in a viscoelastic zone: Implications for faster ductile faulting and earthquakes in the spinel stability field. Earth Planet. Sci. Lett. 182, 171–185 (2000)

    Article  ADS  CAS  Google Scholar 

  23. Kameyama, M. C., Yuen, D. A. & Fujimoto, H. The interaction of viscous heating with grain-size dependent rheology in the formation of localized slip zones. Geophys. Res. Lett. 168, 159–162 (1997)

    Google Scholar 

  24. Kameyama, M. C., Yuen, D. A. & Karato, S.-I. Thermal-mechanical effects of low temperature plasticity (the Peierls mechanism) on the deformation of a viscoelastic shear zone. Earth Planet. Sci. Lett. 168, 159–162 (1999)

    Article  ADS  CAS  Google Scholar 

  25. Regenauer-Lieb, K. & Yuen, D. A. Modeling shear zones in geological and planetary sciences: Solid- and fluid-thermal-mechanical approaches. Earth Sci. Rev. 63, 295–349 (2003)

    Article  ADS  Google Scholar 

  26. Hirth, G. & Kohlstedt, D. in Inside the Subduction Factory (ed. Eiler, J.) 83–105 (Geophysical Monograph 138, American Geophysical Union, Washington DC, 2003)

    Book  Google Scholar 

  27. Goetze, G. The mechanisms of creep in olivine. Phil. Trans. R. Soc. Lond. A 288, 99–119 (1978)

    Article  ADS  CAS  Google Scholar 

  28. van der Wal, D., Chopra, P., Drury, M. R. & Fitz-Gerald, J. Relationships between dynamically recrystallized grain size and deformation conditions in experimentally deformed olivine rocks. Geophys. Res. Lett. 20, 1479–1482 (1993)

    Article  ADS  Google Scholar 

  29. Jiao, W., Silver, P. G., Fei, Y. & Prewitt, C. T. Do intermediate- and deep-focus earthquakes occur on preexisting weak zones? An examination of the Tonga subduction zone. J. Geophys. Res. 105, 28125–28138 (2000)

    Article  ADS  Google Scholar 

  30. Shimada, M., Cho, A. & Yukutake, H. Fracture strength of dry silicate rocks at high confining pressures and activity of acoustic emission. Tectonophysics 96, 159–172 (1983)

    Article  ADS  Google Scholar 

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Two colleagues were instrumental in helping with this paper: J. Whitehead guided us toward a steady state, and M. Spiegelman helped with a faster thermal diffusion code. In addition we gratefully acknowledge discussions with E. Coon, A. Rubin, P. Molnar, D. McKenzie, M. Billen, J. Gaherty, J. McGuire, L. Montesi, S. Kirby, B. Hacker and J. Warren. This work was supported, in part, by several NSF research grants, the Charles Francis Adams Chair at WHOI (P.B.K.), the Arthur D. Storke Chair at Columbia University (P.B.K.), and a Fellowship from the WHOI Deep Ocean Exploration Institute (G.H.).

Author Contributions While learning from G.H. about the weak fault controversy in Oman, P.B.K. proposed the possibility of a periodic shear heating instability in an upper mantle shear zone of fixed width. P.B.K. constructed the numerical model, and devised the analytical approximation. G.H. provided essential insight on rock mechanics, supplying formulations for olivine flow laws, grain size evolution, stress variation with and without inertial terms, elastic relaxation, and references to prior work on all these topics. G.H. proposed applying the model to intermediate-depth earthquakes. Both authors contributed equally to evaluating and extending model results within natural parameter ranges for temperature, stress, grain size, shear-zone width, and so on, based on our ongoing joint field work.

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Correspondence to Peter B. Kelemen.

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This file contains Supplementary Discussion, Supplementary Figures S1-S5 with Legends and additional references. (PDF 2638 kb)

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Kelemen, P., Hirth, G. A periodic shear-heating mechanism for intermediate-depth earthquakes in the mantle. Nature 446, 787–790 (2007).

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