pure and applied geophysics

, Volume 135, Issue 4, pp 529–543 | Cite as

Body-wave waveform constraints on the source parameters of the Yangjiang, China, earthquake of July 25, 1969: A devastating earthquake in a stable continental region

  • Benjamin J. Brantley
  • Wai-Ying Chung


On July 25, 1969, anM s 5.9 earthquake shook the Kwangtung Province near Yangjiang, China. Casualties and extensive damage were reported in the epicentral area. The Yangjiang earthquake occurred within the passive margin located along China's southeast coast. This stable continental setting is seismically one of the most quiet regions of China; historic records indicate this earthquake to have been the first devastating one in the area. A remarkable feature of this earthquake sequence is that its foreshocks and aftershocks are relatively small in terms of number and magnitude despite the relatively large main shock.

Waveforms of long-and short-period teleseismicP and long-period teleseismicSH waves have been modeled to estimate the source parameters for this earthquake. The focal mechanism determined is predominately strike-slip with a small normal component (strike=263°, dip=79°, rake=194°) and is in good agreement with observations in the epicentral area regarding dislocation direction of fissures, distribution of aftershocks, and isoseismals. The average seismic moment is 5.15×1024 dyne-cm and the focal depth is estimated to be 9 km. The earthquake is characterized by a rather short source-time function and a high stress drop of approximately 380 bars. The observed pattern of the foreshock-main shock-aftershock sequence is interpreted in terms of the large stress drop associated with the main shock and the material properties at and near the source. TheP-axis orientation lies roughly NW-SE and is consistent with the maximum compressive stress observed along the coast of southeast China. This stress orientation is consistent with the NW subducting Philippine Sea plate and the SE ward push from central China due to the convergence between Indian and Eurasian subcontinents.

Key words

Source parameters waveform constraints Yangjiang earthquake southeast China 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Aki, K. (1966),Generation and Propagation of G Waves from the Niigata Earthquake of June 16, 1964, Bull. Earthquake Res. Inst., Tokyo Univ.44, 23–88.Google Scholar
  2. Båth, M. (1965),Lateral Inhomogeneities of the Upper Mantle, Tectonophysics2, 483–514.Google Scholar
  3. Chung, W.-Y., andBrantley, B. J. (1989)The 1984 Southern Yellow Sea Earthquake of Eastern China: Source Properties and Seismotectonic Implications for a Stable Continental Area, Bull. Seismol. Soc. Am.79, 1863–1882.Google Scholar
  4. Chung, W.-Y., andCipar, J. J. (1983),Source Modeling of the Hsingtai, China Earthquakes of March 1966, Phys. Earth Planet. Inter.33, 111–125.Google Scholar
  5. Cipar, J. (1981),Broadband Time Domain Modelling of Earthquakes from Friuli, Italy, Bull. Seismol. Soc. Am.71, 1215–1231.Google Scholar
  6. Ebel, J. E., Burdick, L. J., andStawart, G. S. (1978),The Source Mechanism of August 7, 1966 El Golfo Earthqake, Bull. Seismol. Soc. Am.68, 1281–1292.Google Scholar
  7. Geller, R. J. (1976),Scaling Relations for Earthquake Source Parameters and Magnitudes, Bull. Seismol. Soc. Am.66, 1501–1523.Google Scholar
  8. Helmberger, D. V. (1974),Generalized Ray Theory for Shear Dislocations, Bull. Seismol. Soc. Am.64, 45–64.Google Scholar
  9. Huang, T. K. (1978),An Outline of the Geological Characteristids of China, Eclogae Geol. Helv.71 (3), 611–635.Google Scholar
  10. Johnston, A. C.,The seismicity of “stable continental interiors”, InEarthquakes at North-Atlantic Passive Margins: Neotectonics and Postglacial Rebound (Gregersen, S. and Basham, P. W., eds) (Kluwer Academic Publishers, Dordrecht, Netherlands 1989) pp. 299–327.Google Scholar
  11. Kanamori, H., andAllen, C. R. (1986),Earthquake repeat time and average stress drop, InEarthquake Source Mechanics (S. Das, J. Boatwright, and C. H. Scholz, eds.), Am. Geophys. Union Geophysical Monograph37, 227–235.Google Scholar
  12. Kanamori, H., andAnderson, D. L. (1975),Theoretical Basis of Some Empirical Relations in Seismology, Bull. Seismol. Soc. Am.65, 1073–1095.Google Scholar
  13. Kanamori, H., andStewart, G. S. (1976),Mode of Strain Release along the Gibbs Fracture Zone, Mid Atlantic Ridge, Phys. Earth Planet. Inter.11, 312–332.Google Scholar
  14. Keiles-Borok, V. (1959),An Estimation of the Displacement in an Earthquake Source and of Source Dimensions, Ann. Geofis. (Rome)12, 205–214.Google Scholar
  15. Ku, K.-H.,A Catalog of Earthquakes in China (Science Press, Beijing 1983), 894 pp. (in Chinese).Google Scholar
  16. Langston, C. A. (1987),Depth of Faulting During the 1968 Meckering, Australia, Earthquake Sequence Determined from Waveform Analysis of Local Seismograms, J. Geophys. Res.92, 11561–11574.Google Scholar
  17. Langston, C. A., andHelmberger, D. V. (1975),A Procedure for Modeling Shallow Dislocation Sources, Geophys. J. R. astr. Soc.42, 117–130.Google Scholar
  18. Li, Y., McWilliams, M., Cox, A., Sharps, R., Li, Y., Gao, Z., Zhang, Z., andZhai, Y. (1988),Late Permian Paleomagnetic Pole from Dikes of the Tarim Craton, China. Geology16, 275.Google Scholar
  19. Lin, B., Dong, D., Lin, J., andHu, X. (1989),A Study on the Inversion of Rupture Process by the Compound Model Method, Acta Seismologica Sinica2, 481–496.Google Scholar
  20. Lin, J.-Z., Liang, G.-Z., Zhao, Y., andXie, M.-F. (1980),Focal Mechanis and Tectonic Stress Field of Coastal Southeast China, Acta Seismologica Sinica2, 245–257 (in Chinese).Google Scholar
  21. Mogi, K. (1963),Some Discussions on Aftershocks, Foreshocks and Earthquake Swarms—The Fracture of a Semi-infinite Body Caused by an Inner Stress Origin and its Relation to Earthquake Phenomena (third paper), Bull. Earthquake Res. Inst., Tokyo Univ.41, 595–614.Google Scholar
  22. Molnar, P., Fitch, T., andWu, F., (1973),Fault Plane Solutions of Shallow Earthquakes and Contemporary Tectonics of Asia, Earth and Planet. Sci. Lett.19, 101–112.Google Scholar
  23. Richardson, R. M., andSolomon, S. C. (1976),Intraplate Stress as an Indicator of Plate Tectonic Driving Forces, J. Geophys. Res.81, 1847–1856.Google Scholar
  24. Richter, C. F.,Elementary Seismology (W. H. Freeman, San Francisco, Calif. 1958) 763 pp.Google Scholar
  25. Sykes, L. R., andSbar, M. L. (1973),Intraplate Earthquakes, Lithospheric Stresses and the Driving Mechanism of Plate Tectonics, Nature245, 298–302.Google Scholar
  26. Tapponnier, P., andMolnar, P. (1977),Active Faulting and Cenozoic Tectonics of China, J. Geophys. Res.82, 2905–2903.Google Scholar
  27. Teng, C., Chang, Y., Hsu, K., andFan, F. (1979),On the Tectonic Stress Field in China and its Relation to Plate Movement, Phys. Earth Planet. Inter.18, 257–273.Google Scholar
  28. Wang, S.-C., Geller, L. M., Stein, S., andTaylor, B. (1979),An Intraplate Thrust Earthquake in the South China Sea, J. Geophys. Res.84, 5627–5631.Google Scholar
  29. Wei, B. L., Ding, L. Q., andQin, N. G.,The 1969 July 26, Guangdong Province Yangjiang M s=6.4earthquake, InEarthquake Cases in China (1966–1975), (Z. Zhang, ed.) (Seismological Publishing House 1988), pp. 41–56 (in Chinese).Google Scholar
  30. Wesnousky, S. G., Astiz, L., andKanamori, H. (1986),Earthquake Multiplets in the Southeastern Solomon Islands, Phys. Earth Planet. Inter.44, 304–318.Google Scholar
  31. Xie, Y., andQua, M.,Compilation of Historical Materials of Chinese Earthquakes, Vol. 2 (Science Press, Beijing 1985) 949 pp. (in Chinese).Google Scholar
  32. Xie, Y., andQua, M.,Compilation of Historical Materials of Chinese Earthquakes, Vol. 3 (Science Press, Beijing 1987) 1426 pp. (in Chinese).Google Scholar

Copyright information

© Birkhäuser Verlag 1991

Authors and Affiliations

  • Benjamin J. Brantley
    • 1
  • Wai-Ying Chung
    • 1
    • 2
  1. 1.Center for Earthquake Research and InformationMemphis State UniversityMemphisUSA
  2. 2.Department of Geological SciencesMemphis State UniversityMemphisUSA

Personalised recommendations