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A new self-organizing mechanism for deep-focus earthquakes

Nature volume 341, pages 733737 (26 October 1989) | Download Citation

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Abstract

THE mechanism of deep-focus earthquakes has been a puzzle since their discovery almost 70 years ago1, 2, because brittle fracture and frictional sliding at depths in excess of 100–200 km would require unrealistic rock strengths3, 4. Rock strength does increase with pressure, but a few hundred MPa (equivalent to 10–20 km depth) suffices to inhibit most fracture, and elevated temperature activates ductile mechanisms that operate at stresses less than the fracture stength. A range of mechanisms has been proposed for deep earthquakes, including plastic instabilities5–7, shear-induced melting8–11 and instabilities accompanying recrystallization12, 13 or polymorphic phase transformation14–23. Each of these proposed mechanisms has exhibited certain inherent weaknesses (see Kirby22 for review and discussion). Here we report experimental observations of high-pressure faulting of metastable Mg2GeO4 olivine as it undergoes incipient transformation to a spinel 24, 25 structure. We present a model in which this faulting arises from the generation, propagation and linking-up of spinel-filled anticracks26. When applied to the olivine → spinel transformation in the Earth's mantle, the anticrack model27 satisfactorily accounts for the similarities and differences between shallow and deep earthquakes and removes the problems associated with frictional sliding.

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References

  1. 1.

    Mon. Not. R. astr. Soc., Geophys. Suppl. 1, 1–13 (1922).

  2. 2.

    Geophys. Mag. 1, 162–202 (1928).

  3. 3.

    The Earth, Its Origin, History and Physical Constitution 2nd Edn (Cambridge University Press, 1929).

  4. 4.

    Proc. R. Soc. Edinb. 56, 158–163 (1936).

  5. 5.

    J. Geol. 44, 653–669 (1936).

  6. 6.

    Geol. Soc. Am. Mem. 79, 323–345 (1960).

  7. 7.

    & J. geophys. Res. 93, 10,521–10,540 (1988).

  8. 8.

    in Nature of the Solid Earth (ed. Robertson, E. C.) 361–384 (McGraw-Hill, New York, 1972).

  9. 9.

    Tectonophysics 42, 75–110 (1977).

  10. 10.

    in Modern Physics for the Engineer (ed. Ridenour, L. N.) 272–305 (McGraw-Hill, New York, 1954).

  11. 11.

    & Geol. Soc. Am. Mem. 79, 347–373 (1960).

  12. 12.

    & in Properties of Matter under Unusual Conditions, (eds Mark, H. & Fernback, S.) (Wiley Interscience, New York 1969).

  13. 13.

    J. geophys. Res. 92, 13,801–13,810 (1987).

  14. 14.

    Am. J. Sci. 243A, 90–97 (1945).

  15. 15.

    Bull. seism. Soc. Am. 53, 893–903 (1963).

  16. 16.

    Bull. seism. Soc. Am. 53, 873–891 (1963).

  17. 17.

    Bull. seism. Soc. Am. 57, 9–25 (1967).

  18. 18.

    & J. geophys. Res. 81, 985–988 (1976).

  19. 19.

    & Tectonophysics 31, 1–32 (1976).

  20. 20.

    Phys. Earth planet Inter. 32, 226–240 (1983).

  21. 21.

    Phys. Earth planet. Inter. 34, 221–225 (1984).

  22. 22.

    J. geophys. Res. 92, 13,789–13,800 (1987).

  23. 23.

    & Nature 339, 616–618 (1989).

  24. 24.

    & Eos 70, 473 (1989).

  25. 25.

    & J. geophys. Res. (submitted).

  26. 26.

    & Eos 70, 473 (1989).

  27. 27.

    & Geology 9, 419–424 (1981).

  28. 28.

    & Nature 338, 753–756 (1989).

  29. 29.

    , & Tectonophysics 108, 299–322 (1984).

  30. 30.

    Tectonophysics 75, T29–T36 (1981).

  31. 31.

    Experimental Rock Deformation—The Brittle Field (Springer, Berlin, 1973).

  32. 32.

    & Tectonics 7, 1243–1256 (1988).

  33. 33.

    & J. geophys. Res. 86, 389–404 (1981).

  34. 34.

    Geophys. Res. Lett. 11, 817–820 (1984).

  35. 35.

    & J. geophys. Res. 92, 4853–4866 (1987).

  36. 36.

    A. Rev. Earth planet. Sci. 17, 227–254 (1989).

  37. 37.

    & Geodynamics (Wiley, New York, 1982).

  38. 38.

    in High Pressure Science and Technology Vol. 2 (eds Timmerhaus, K. D. & Barber M. S.) 31–42 (Plenum, New York, 1979).

  39. 39.

    & J. geophys. Res. 92, 13,927–13,943 (1987).

  40. 40.

    J. geophys. Res. 71, 2981–3006 (1966).

  41. 41.

    & J. geophys. Res. 70, 3965–3985 (1965).

  42. 42.

    & Phys. Chem. Miner. 14, 473–481 (1987).

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Affiliations

  1. Department of Geology, University of California, Davis, California 95616, USA

    • H. W. Green II
    •  & P. C. Burnley

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https://doi.org/10.1038/341733a0

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