Case 2: Foreshocks to the Haicheng Earthquake of 1975. Certain Characteristics of the Haicheng Earthquake (M=7.3) Sequence

  1. Max Wyss
  1. K.-T. Wu,
  2. M.-S. Yue,
  3. H.-Y. Wu,
  4. S.-L. Chao,
  5. H.-T. Chen,
  6. W.-Q. Huang,
  7. K.-Y. Tien and
  8. S.-D. Lu

Published Online: 3 APR 2013

DOI: 10.1029/SP032p0012

Evaluation of Proposed Earthquake Precursors

Evaluation of Proposed Earthquake Precursors

How to Cite

Wu, K.-T., Yue, M.-S., Wu, H.-Y., Chao, S.-L., Chen, H.-T., Huang, W.-Q., Tien, K.-Y. and Lu, S.-D. (2013) Case 2: Foreshocks to the Haicheng Earthquake of 1975. Certain Characteristics of the Haicheng Earthquake (M=7.3) Sequence, in Evaluation of Proposed Earthquake Precursors (ed M. Wyss), American Geophysical Union, Washington, D. C.. doi: 10.1029/SP032p0012

Author Information

  1. Chinese Geophysics, AGU, 1, 289-308, 1978

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

This paper deals with the seismicity (the earthquake sequence and its spatial distribution) related to the Haicheng earthquake of February 4, 1975.

Normally, very low seismic activity existed around the meizoseismal region of the Haicheng earthquake. However, beginning February 1, 1975, 527 foreshocks were counted at the Shipengyu seismograph station located about 20 km from the epicenters. The epicenters of these foreshocks were densely concentrated, and the sense of the P-wave first motions was similar. With respect to the time of occurrence, the succession consisted of a concentration of foreshocks followed by a period of quiescence and finally the main shock. Following the main shock, numerous aftershocks occurred.

The direction of the major axis of the meizoseismal region of the main shock coincides with both that of the aftershock distribution and the direction of the nodal plane A, from the earthquake fault plane solution. From this the strike of the dislocation plane of the main shock was interpreted to be WNW. The fault appears to be left lateral strike-slip with a high angle of dip.

Some discussion is also given to a possible method of imminent earthquake prediction.