pure and applied geophysics

, Volume 138, Issue 3, pp 407–427 | Cite as

A crack-like rupture model for the 19 September 1985 Michoacan, Mexico, earthquake

  • Stanley D. Ruppert
  • Kiyoshi Yomogida


Evidence supporting a smooth crack-like rupture process of the Michoacan earthquake of 1985 is obtained from a major earthquake for the first time. Digital strong motion data from three stations (Caleta de Campos, La Villita, and La Union), recording near-field radiation from the fault, show unusually simple ramped displacements and permanent offsets previously only seen in theoretical models. The recording of low frequency (0 to 1 Hz) near-field waves together with the apparently smooth rupture favors a crack-like model to a step or Haskell-type dislocation model under the constraint of the slip distribution obtained by previous studies. A crack-like rupture, characterized by an approximated dynamic slip function and systematic decrease in slip duration away from the point of rupture nucleation, produces the best fit to the simple ramped displacements observed. Spatially varying rupture duration controls several important aspects of the synthetic seismograms, including the variation in displacement rise times between components of motion observed at Caleta de Campos. Ground motion observed at Caleta de Campos can be explained remarkably well with a smoothly propagating crack model. However, data from La Villita and La Union suggest a more complex rupture process than the simple crack-like model for the south-eastern portion of the fault.

Key words

Crack-like rupture near-fault seismogram Michoacan earthquake 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Aki, K. (1968),Seismic Displacement Near a Fault, J. Geophys. Res.73, 1359–1376.Google Scholar
  2. Aki, K., andRichards, P. G. Quantitative Seismology: Theory and Methods (W. H. Freeman, San Francisco 1980).Google Scholar
  3. Anderson, J. G., Bodin, P., Brune, J. N., Prince, J., Singh, S. K., Quaas, R., andOnate, M. (1986),Strong Ground Motion from the Michoacan Mexico Earthquake, Science233, 1043–1049.Google Scholar
  4. Archuleta, R. (1984),A Faulting Model for the 1979 Imperial Valley Earthquake, J. Geophys. Res.89, 4559–4585.Google Scholar
  5. Archuleta, R., andHartzell, S. (1981),Effect of Fault Finiteness on Near-source Ground Motion, Bull. Seismol. Soc. Am.71, 939–957.Google Scholar
  6. Astiz, L., Kanamori, H., andEissler, H. (1987),Source Characteristics of Earthquakes in the Michoacan Seismic Gap in Mexico, Bull. Seismol. Soc. Am.77, 1326–1346.Google Scholar
  7. Beroza, G., andSpudich, P. (1988),Linearized Inversion for Fault Rupture Behavior: Application to the 1984 Morgan Hill, California Earthquake, J. Geophys. Res.93, 6275–6296.Google Scholar
  8. Bodin, P. andKlinger, T. (1986),Coastal Uplift and Mortality of Intertidal Organisms Caused by the September 1985 Mexico Earthquake, Science233, 1071–1073.Google Scholar
  9. Bouchon, M. (1978),A Dynamic Source Model for the San Fernando Earthquake, Bull. Seismol. Soc. Am.68, 1555–1575.Google Scholar
  10. Bouchon, M. (1979),A Discrete Wavenumber Representation of Elastic Wave Fields in Three-space Dimensions, J. Geophys. Res.84, 3609–3614.Google Scholar
  11. Brune, J. (1970),Tectonic Stress and the Spectra of Seismic Shear Waves from Earthquakes, J. Geophys. Res.75, 4997–5009.Google Scholar
  12. Burridge, R., andKnopoff, L. (1964),Body Force Equivalents for Seismic Dislocations, Bull. Seismol. Soc. Am.64, 1874–1888.Google Scholar
  13. Burridge, R., andWillis, J. R. (1969),The Self-similar Problem of the Expanding Elliptical Crack in an Anisotropic Solid, Proc. Cambridge Phil. Soc.66, 443–468.Google Scholar
  14. Campillo, M., Gariel, J. C., Aki, K., andSánchez-Sesma, F. J. (1989),Destructive Strong Ground Motion in Mexico City: Source, Path, and Site Effects during the Great 1985 Michoacan Earthquake, Bull. Seismol. Soc. Am.79, 1718–1735.Google Scholar
  15. Das, S., andAki, K. (1970),Fault Planes with Barriers: A Versatile Earthquake Model, J. Geophys. Res.82, 5648–5670.Google Scholar
  16. Das, S., andKostrov, B. V. (1985),An Elliptical Asperity in Shear-fracture Process and Seismic Radiation, Geophys. J. R. Astron, Soc.80, 725–742.Google Scholar
  17. Day, S. (1982),Three-dimensional Finite Difference Simulation of Fault Dynamics: Rectangular Faults with Fixed Rupture Velocity, Bull. Seismol. Soc. Am.72, 703–727.Google Scholar
  18. Ekström, G., andDziewonski, A. M. (1986),A Very Broad-band Analysis of the Michoacan Mexico Earthquake of September 19, 1985, Geophys. Res. Lett.13, 605–608.Google Scholar
  19. Haskell, N. A. (1968),Elastic Displacements in the Near-field of Propagating Fault, Bull. Seismol. Soc. Am.59, 865–908.Google Scholar
  20. Iwan, W. D., Moser, M. A., andPeng, C.-Y. (1985),Some Observations on Strong-motion Earthquake Measurements using a Digital Accelerograph, Bull. Seismol. Soc. Am.75, 1225–1246.Google Scholar
  21. Kostrov, B. V. (1964),Self-similar Problems of Propagation of Shear Cracks, J. Appl. Math. Mech. (Engl. Trans.)28, 1077–1087.Google Scholar
  22. Madariaga, R. (1976),Dynamics of an Expanding Circular Fault, Bull. Seismol. Soc. Am.66, 639–666.Google Scholar
  23. Madariaga, R. (1977),High Frequency Radiation from Crack (Stress Drop) Models of Earthquake Faulting, Geophys. J. R. Astron. Soc.51, 625–651.Google Scholar
  24. Mansinha, L., andSmylie, D. E. (1971),The Displacement Field of Inclined Faults, Bull. Seismol. Soc. Am.61, 1433–1440.Google Scholar
  25. Mendoza, C., andHartzell, S. (1989),Slip Distribution of the 19 September 1985 Michoacan, Mexico, Earthquake: Near-source and Teleseismic Constraints, Bull Seismol. Soc. Am.79, 655–669.Google Scholar
  26. Mendoza, C., andAnderson, J. G. (1991),The Temporal and Spatial Evolution of the 19 September 1985 Michoacan Earthquake as Inferred from Near-source Ground-motion Records Bull. Seismol. Soc. Am.81, 844–861.Google Scholar
  27. Mikumo, T., andMiyatake, T. (1978),Dynamical Rupture Process on a Three-dimensional Fault with Non-uniform Frictions and Near-field Seismic Waves, Geophys. J. R. Astron. Soc.54, 417–438.Google Scholar
  28. Olson, A., Orcutt, J., andFrazier, G. (1984),The Discrete Wavenumber/Finite Element Method of Synthetic Seismograms, Geophys. J. R. Astron. Soc.77, 421–460.Google Scholar
  29. Priestley, K., andMasters, T. G. (1986),Source Mechanism of the September 19, 1985 Michoacan Earthquake and its Implication, Geophys. Res. Lett.13, 601–604.Google Scholar
  30. Sato, T., andHirasawa, T. (1973),Body Wave Spectra from Propagating Shear Cracks, J. Phys. Earth21, 415–431.Google Scholar
  31. Singh, S. K., andSaurez, G. (1988),Regional Variations in the Number of Aftershocks of Large Subduction Zone Earthquakes, Bull. Seismol. Soc. Am.78, 230–242.Google Scholar
  32. Spudich, P., (1980),The de Hoop-Knopoff Representation Theorem as a Linear Inverse Problem, Geophys. Res. Lett.7, 717–720.Google Scholar
  33. Stolte, C., McNally, K. C., andGonzalez-Ruiz, J. (1986),Fine Structure of a Post-failure Wadati-Benioff Zone, Geophys. Res. Lett.13, 577–580.Google Scholar
  34. UNAM-Seimology-Group (1986),The September 1985 Michoacan, Earthquake: Afreshock Distribution and Histoory of Rupture, Geophys. Res. Lett.13, 573–576.Google Scholar
  35. Yomogida, K. (1988),Crack-like Rupture Processes Observed in Near-fault Strong Motion Data, Geophys. Res. Lett.15, 1223–1226.Google Scholar

Copyright information

© Birkhäuser Verlag 1992

Authors and Affiliations

  • Stanley D. Ruppert
    • 1
  • Kiyoshi Yomogida
    • 1
  1. 1.Department of GeophysicsStanford UniversityStanfordUSA

Personalised recommendations