Skip to main content

Volume 57 Supplement 4

Special Issue: Special Section for the 2004 off the Kii peninsula earthquakes (2)

The 2004 sequence of triggered earthquakes off the Kii peninsula, Japan


We examine the spatial and temporal relationships of the sequence of strong earthquakes that occurred off the Kii Peninsula, Japan, on 5 September 2004. The first event (Mj 7.1) occurred at 10:07:08 (UTC) on a northward dipping plane within the subducting Philippine Sea plate. From 10:16 to 14:47 the seismicity shows a group of earthquakes (Mj 3.2 to 4.8) 35 km to the east which are regarded as foreshocks to the second large earthquake. At 14:57:17, a Mw 6.1 strike-slip event occurred on a northwest trending plane. Some 14 seconds later, a large (Mj 7.4) thrust earthquake started 4.2 km southeast of the initial epicenter of the second earthquake. This largest earthquake is thought to have occurred on a southward dipping plane with the strike in an east-southeastly direction. Using the geometry of faults determined in this study, calculations of the Coulomb failure function show that simple static stress changes do not provide a good explanation for the triggering of the subsequent earthquakes.


  • Abercrombie, R. A. and J. Rice, Can observations of earthquake scaling constrain slip weakening? Geophys. J. Int., 2005 (in press).

    Google Scholar 

  • Baba, T., P. R. Cummins, and T. Hori, Compound fault rupture during the 2004 off the Kii Peninsula earthquake (M 7.4) inferred from highly resolved coseismic sea-surface deformation, Earth Planets Space, 57, 167–172, 2005.

    Article  Google Scholar 

  • Christensen, D. and L. J. Ruff, Seismic coupling and outer rise earthquakes, J. Geophys. Res., 93, 13,421–13,444, 1988.

    Article  Google Scholar 

  • Enescu, B., J. Mori, and S. Ohmi, Double-difference relocations of the 2004 off the Kii peninsula earthquakes, Earth Planets Space, 57, this issue, 357–362, 2005.

    Article  Google Scholar 

  • Gomberg, J., P. Bodin, and P. A. Reasenberg, Observing earthquake triggering in the near field by dynamic deformations, Bull. Seism. Soc. Am., 93, 118–138, 2003.

    Article  Google Scholar 

  • Hartzell, S. H. and T. H. Heaton, Inversion of strong ground motion and teleseismic waveform data for the fault rupture history of the 1979 Imperial Valley, California earthquake, Bull. Seism. Soc. Am., 73, 1553–1583, 1983.

    Google Scholar 

  • Jones, L. M., Foreshocks (1966–1980) in the San Andreas system, California, Bull. Seism. Soc. Am., 74, 1361–1380, 1984.

    Google Scholar 

  • King, G. C. P., R. S. Stein, and J. Lin, Static stress changes and the triggering of earthquakes, Bull. Seismol. Soc. Am., 84, 935–953, 1994.

    Google Scholar 

  • Langston, C. A. and D. V. Helmberger, A procedure for modeling shallow dislocation sources, Geophys. J. R. astr. Soc., 42, 117–130, 1975.

    Article  Google Scholar 

  • Lawson, C. L. and R. J. Hanson, Solving Least-Squares Problems, 340 pp, Prentice-Hall, Inc., Englewood Cliffs, New Jersey, 1974.

    Google Scholar 

  • Nakanishi, A., N. Takahashi, J-O. Park, S. Miura, S. Kodaira, Y. Kaneda, N. Hirata, T. Iwasaki, and M. Nakamura, Crustal structure across the coseismic rupture zone of the 1944 Tonankai earthquake, the central Nankai Trough seismogenic zone, J. Geophysic. Res., 107, B1, 10.1029/2001JB000424, 2002.

    Google Scholar 

  • Okada, Y., Internal deformation due to shear and tensile faults in a halfspace, Bull. Seism. Soc. Am., 82, 1018–1040, 1992.

    Google Scholar 

  • Satake, K., T. Baba, K. Hirata, S. Iwasaki, T. Kato, S. Koshimura, J. Takenaka, and Y. Terada, Tsunami source of the 2004 off the Kii Peninsula earthquakes inferred from offshore tsunami and coastal tide gauges, Earth Planets Space, 57, 173–178, 2005.

    Article  Google Scholar 

  • Stein, R. S., The role of stress transfer in earthquake occurrence, Nature, 402, 605–609, 1999.

    Article  Google Scholar 

  • Wu, C., K. Koketsu, and K. Hikima, Analysis of the source rupture process of the Southeast Off-shore Kii Peninsula earthquake from strong-motion records, 2004 Fall Meeting of the Seismological Society of Japan, 2004 (in Japanese).

    Google Scholar 

  • Yagi, Y., T. Hara, and T. Kashima, Strong-motion records, CMT, and source process of the earthquake that occurred on September 5, 2004 southeast off-shore of the Kii Peninsula, 2004 Fall Meeting of the Seismological Society of Japan, 2004 (in Japanese).

    Google Scholar 

  • Yamanaka, Y., Source process of the 2004 Southeast Off-shore Kii Peninsula earthquake, 2004 Fall Meeting of the Seismological Society of Japan, 2004 (in Japanese).

    Google Scholar 

Download references

Author information

Authors and Affiliations


Corresponding author

Correspondence to Sun-Cheon Park.

Rights and permissions

Open Access  This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made.

The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.

To view a copy of this licence, visit

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Park, SC., Mori, J. The 2004 sequence of triggered earthquakes off the Kii peninsula, Japan. Earth Planet Sp 57, 315–320 (2005).

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

Key words

  • Kii Peninsula
  • Nankai Trough
  • slip distribution
  • static stress
  • triggering
  • foreshocks