Skip to main content


Co-seismic slip, post-seismic slip, and aftershocks associated with two large earthquakes in 1996 in Hyuga-nada, Japan

Article metrics


We analyzed continuous GPS data to investigate the spatial distribution of post-seismic slip associated with two large earthquakes of October 19 and December 2, 1996, in Hyuga-nada, Japan. We found that the moment release due to post-seismic events was comparable to the co-seismic moment release during the two earthquakes. The source parameters of the first post-seismic event are as follows: the moment release = 1.7 × 1019 Nm; the maximum slip = 0.06 m at about 50 km northwest from the epicenter of the first earthquake; the characteristic decay time (= final slip/initial slope) = 15 days. For the second post-seismic event, the moment release = 2.0 × 1019 Nm; the maximum slip = 0.13 m at about 15 km northwest from the epicenter of the second earthquake; the characteristic time = 100 days. In both events, the slip vectors of the downgoing Philippine Sea (PHS) Plate on the SW-striking interplate boundary are directed west, in accordance with the co-seismic slip. It is also shown that the sites for co-seismic slip, post-seismic slip, and aftershocks do not overlap but complementarily share the plate boundary. This suggests that individual sites are characterized by their own constitutive laws, which may control modes of moment release as well as the entire sequence.


  1. Akaike, H., Likelihood and bayes procedure, in Bayesian Statistics, edited by J. M. Bernardo, M. H. DeGroot, D. V. Lindley, and A. F. M. Smith, pp. 143–166, University Press, Valencia, Spain, 1980.

  2. Heki, K., S. Miyazaki, and H. Tsuji, Silent fault slip following an interplate thrust earthquake at the Japan trench, Nature, 386, 595–598, 1997.

  3. Hirose, H., K. Hirahara, F. Kimata, N. Fujii, and S. Miyazaki, A slow thrust slip event following the two 1996 Hyuganada earthquakes beneath the Bungo Channel, southwest Japan, Geophys. Res. Lett., 26, 3237–3240, 1999.

  4. Ide, S., M. Takeo, and Y. Yoshida, Source process of the 1995 Kobe earthquake: determination of spatio-temporal slip distribution by Bayesian modeling, Bull. Seism. Soc. Am., 86, 547–566, 1996.

  5. Langbein, J. and H. Johnson, Correlated errors in geodetic time series: implicationsfor time-dependent deformation, J. Geophys. Res., 102, 591–603, 1997.

  6. Maruyama, T., Static elastic dislocation in an infinite and semi-infinite medium, Bull. Earthq. Res. Inst., 42, 289–368, 1964.

  7. Nishimura, T., The Spatiotemporal Distribution of Coseismic and Postseismic Slip Associated with the 1994 Far Off Sanriku Earthquake, M. Sc. Thesis, University of Tohoku, 1997.

  8. Peacock, S. M. and K. Wang, Seismic consequences of warm versus cool subduction metamorphism: examples from southwest and northeast Japan, Science, 286, 937–939, 1999.

  9. Scholz, C. H., The Mechanics of Earthquake and Faulting, pp. 314–317, Cambridge University Press, New York, 1990.

  10. Scholz, C. H., Earthquake and friction laws, Nature, 391, 37–42, 1998.

  11. Segall, P., R. Burgmann, and M. Matthews, Time-dependent triggered afterslip following the 1989 Loma Prieta earthquake, J. Geophys. Res., 105, 5615–5634, 2000.

  12. Seno, T., S. Stein, and A. D. Gripp, A model for motion of the Philippine Sea Plate consistent with NUVEL-1 and Geological Data, J. Geophys. Res., 98, 17941–17948, 1993.

  13. Shen, Z., D. D. Jackson, Y. Feng, M. Cline, M. Kim, P. Fang, and Y. Bock, Postseismic deformation following the Landers Earthquake, California, 28 June 1992, Bull. Seism. Soc. Am., 84, 780–791, 1994.

  14. Smith, S. W. and M. Wyss, Displacement on the San Andreas fault subsequent to the 1966 Parkfield earthquake, Bull. Seis. Soc. Am., 58, 1955–1973, 1968.

  15. Stein, R. S. and M. Lisowski, The 1979 Homestead valley earthquake sequence, California: control of aftershocks and postseismic deformation, J. Geophys. Res., 88, 6477–6490, 1983.

  16. Tada, T., Spreading of the Okinawa Trough and its relation to the crustal deformation in the Kyushu (2), Zishin, 38, 1–12, 1985 (in Japanese).

  17. Tada, T, T. Sagiya, and S. Miyazaki, Crustal deformation in the Japan Islands by using GPS network, Kagaku, 67, 917–927, 1997 (in Japanese).

  18. Thatcher, W. and J. B. Rundle, A viscoelastic coupling model for the cyclic deformation due to periodically repeated earthquakes at subduction zones, J. Geophys. Res., 89, 1984.

  19. Wyatt, F. K., Displacement of surface monuments: horizontal motion, J. Geophys. Res., 87, 979–989, 1982.

  20. Wyatt, F. K., Displacement of surface monuments: vertical motion, J. Geophys. Res., 94, 1655–1664, 1989.

  21. Yabuki, T. and M. Matsu’ura, Geodetic data inversion using a Bayesian information criterion for spatial distribution of fault slip, Geophys. J. Int., 109, 363–375, 1992.

  22. Yagi, Y, M. Kikuchi, S. Yoshida, and T. Sagiya, Comparison of the coseismic rupture with the aftershock distribution in the Hyuga-nada earthquakes of 1996, Geophys. Res. Lett, 26, 3161–3164, 1999.

  23. Yoshida, S., Waveform inversion using ABIC for the rupture process of the 1983 Hindu Kush earthquake, Phys. Earth Planet. Inter., 56, 389–405, 1989.

  24. Yoshida, S., K. Koketsu, B. Shibazaki, T. Sagiya, T. Kato, and Y. Yoshida, Joint inversion of near- and far-field waveforms and geodetic data for rupture process of the 1995 Kobe earthquake, J. Phys. Earth, 44, 437–454, 1996.

Download references

Author information

Correspondence to Yuji Yagi.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark


  • Fault Plane
  • Moment Release
  • Slip Vector
  • Postseismic Deformation
  • Slow Slip