A Simple Rheological Framework for Comparative Subductology

  1. Keiiti Aki and
  2. Renata Dmowska
  1. Shimamoto Toshiko1,
  2. Tetsuzo Seno2 and
  3. Seiyo Uyeda3

Published Online: 18 MAR 2013

DOI: 10.1029/GM076p0039

Relating Geophysical Structures and Processes: The Jeffreys Volume

Relating Geophysical Structures and Processes: The Jeffreys Volume

How to Cite

Toshiko, S., Seno, T. and Uyeda, S. (1993) A Simple Rheological Framework for Comparative Subductology, in Relating Geophysical Structures and Processes: The Jeffreys Volume (eds K. Aki and R. Dmowska), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM076p0039

Author Information

  1. 1

    Earthquake Research Institute, University of Tokyo, 1-1-1 Yayoi, Bunkyo-Ku, Tokyo 113, Japan

  2. 2

    Department of Geophysics, Texas A&M University, College Station, Texas 77863-3114 U.S.A.

  3. 3

    Department of Manne Science and Technology, Tokai University, 3-20-1 Orido, Shimizu, Shizuoka 424, Japan

Publication History

  1. Published Online: 18 MAR 2013
  2. Published Print: 1 JAN 1993

ISBN Information

Print ISBN: 9780875904672

Online ISBN: 9781118669129

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Keywords:

  • Earth sciences—Mathematical models;
  • Geophysics—Mathematical models

Summary

The origin of the diversity of subduction zones, particularly with respect to the maximum size of inter-plate thrust-type earthquakes, is still controversial, and previous models fail to account for why only moderate earthquakes occur in some subduction zones (e.g., Mariana). This paper demonstrates that the diversity of subduction-zone seismicity and the existence of nearly aseismic subducting plate boundaries, free from large and great earthquakes, can be explained by a simple Theological model. The modelsubdivides a subducting plate boundary into three zones: i.e., (1) shallow decoupled zone, (2) intermediate seismogenic zone, and (3) lower aseismic interface that rebounds aseismically following large earthquakes. The first zone, assumed to be shallower than about 30 km, is weak and aseismic due primarily to the massive solution-transfer processes under the presence of abundant H2O released through progressive metamorphism. Without this shallower cutoff, the seismogenic zone becomes too wide and the lack of large and great earthquakes in some subduction zones cannot be explained. The boundary between zones (2) and (3) should be associated with the shift in the frictional properties from velocity weakening to velocity strengthening. Although many factors could be involved in this shift, it is assumed here for simplicity that temperature is the primary factor. A crude examination, using temperature distributions in various subduction zones, reveals that the wider the seismogenic zone (w in km), the greater the expected earthquake magnitude (M s or M w ) and that Ms or Mw = 1.2 (±0.4) log w + 6.5 (±1.6) holds.