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Is the plastic flow uniformly distributed below the seismogenic region?


The cut-off depth of seismicity in and around the Nojima fault broken by the 1995 Kobe earthquake occurring in the intraplate Japan was compared with a brittle-ductile transition depth of the widely-accepted strength profile model of the crust. It was found that the cut-off depth is much deeper than the transition depth under the assumption that wet granite is deformed at a strain rate of 10−15/s. Such a small strain rate implies that the plastic flow is uniformly distributed below the seismogenic region. When the strain rate is assumed to be greater than 10−13, the cut-off depth can be attributed to the transition depth. This suggests that deformation is localized in a narrow fault zone below the seismogenic region even in the intraplate region.


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Correspondence to Yoshihisa Iio.

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Iio, Y., Kobayashi, Y. Is the plastic flow uniformly distributed below the seismogenic region?. Earth Planet Sp 54, 1085–1090 (2002).

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  • Fault Zone
  • Lower Crust
  • Slip Rate
  • Transition Depth
  • Kobe Earthquake