Case 6A: Large Scale Crustal Movements Before and after the 1983 Japan Sea Earthquake

  1. Max Wyss
  1. H. Ishii,
  2. S. Miura and
  3. A. Takagi

Published Online: 3 APR 2013

DOI: 10.1029/SP032p0025

Evaluation of Proposed Earthquake Precursors

Evaluation of Proposed Earthquake Precursors

How to Cite

Ishii, H., Miura, S. and Takagi, A. (1991) Case 6A: Large Scale Crustal Movements Before and after the 1983 Japan Sea Earthquake, in Evaluation of Proposed Earthquake Precursors (ed M. Wyss), American Geophysical Union, Washington, D. C.. doi: 10.1029/SP032p0025

Author Information

  1. J. Phys. Earth., 34, S159-S174, 1986

Publication History

  1. Published Online: 3 APR 2013
  2. Published Print: 1 JAN 1991

ISBN Information

Print ISBN: 9780875907840

Online ISBN: 9781118667873

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Keywords:

  • Earthquake prediction—Evaluation

Summary

Large-scale crustal activity before and after the Japan Sea earthquake with magnitude 7.7 on May 26, 1983 was investigated taking into account microearthquakes, crustal strain, crustal stress, and vertical movements and applying numerical experiments. It is found that about one month prior to the mainshock, anomalous microearthquake swarms took place at some points which were considered to be related to fracture zones. Short-term precursors were not recorded by extensometers and watertube tiltmeters deployed at distances more than 80 km from the epicenter of the mainshock. Observed strain steps explain computed steps based on an assumed fault model. Precursory uplift several years preceding the mainshock was found at the nearest Japan Sea coast to the epicenter by space-time analysis of repeated leveling surveys.