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Volume 56 Supplement 3

Special Issue: Special section for the 2003 Tokachi-oki earthquake

Low frequency events occurred during the sequence of aftershock activity of the 2003 Tokachi-Oki earthquake; a dynamic process of the tectonic erosion by subducted seamount


During the sequence of aftershock activity of the 2003 Tokachi-Oki earthquake, anomalous events predominant in low-frequency components occurred very close to a subducted seamount around the junction between the Kuril Trench and the Japan Trench. The low-frequency wave train in the coda part reflects the strong excitation of surface waves and the source depth is considered to be very shallow. The focal mechanism of the low-frequency event is a type of the reverse fault. Considering with the source depth and the mechanism, the low-frequency event might have occurred on the plate boundary as a dynamic process of the tectonic erosion by the subducted seamount.


  • Earthquake Research Committee, Long-term evaluation of earthquakes along the Kuril Trench (March 14 2003 corrected on August 14 2003),, The Headquarters for Earthquake Research Promotion, Tokyo, 2003.

    Google Scholar 

  • Honda, R., S. Aoi, N. Morikawa, H. Sekiguchi, T. Kunugi, and H. Fujuwara, Ground motion and rupture process of the Tokachi-Oki Earthquake obtained from strong motion data of K-NET and KiK-net, Earth Planets Space, 56, this issue, 317–322, 2004.

    Article  Google Scholar 

  • Hyndman, R. D., M. Yamano, and D. A. Oleskevich, The seismogenic zone of subduction thrust faults, The Island Arc, 6, 244–260, 1997.

    Article  Google Scholar 

  • Ito, Y., H. Matsubayashi, H. Kimura, T. Matsumoto, Y. Asano, and S. Sekiguchi, Spatial distribution for moment tensor solutions of the 2003 Tokachi-oki earthquake (MJMA=8.0) and aftershocks, Earth Planets Space, 56, this issue, 301–306, 2004.

    Article  Google Scholar 

  • JMA, Sketch of the Tokachi-Oki earthquake in 2003, Reports of the Coordinating Committee for Earthquake Prediction, 71, 84–95, 2004.

    Google Scholar 

  • KAIKO I Research Group, Topography and structure of trenches around Japan—Data atlas of France-Japanese KAIKO project, Phase I., University of Tokyo Press, Tokyo, 305 pp., 1986.

    Google Scholar 

  • Katsumata, K., N. Wada, and M. Kasahara, Newly imaged shape of the deep seismic zone within the subducting Pacific plate beneath the Hokkaido corner, Japan-Kurile arc-arc junction, J. Geophys. Res., 2004 (in press).

    Google Scholar 

  • Koketsu, K., K. Hikima, S. Miyazaki, and S. Ide, Joint inversion of strong motion and geodetic data for the source process of the 2003 Tokachi-oki, Hokkaido, earthquake, Earth Planets Space, 56, this issue, 329–334, 2004.

    Article  Google Scholar 

  • Kuramoto, S., A. Taira, N. L. Bangs, T. H. Shipley, G. F. Moore, and EW99-07, 08 Scientific Parites, Seismogenic zone in the Nankai accretionary wedge: General summary of Japan-U.S. collaborative 3-D seismic investigation, J. Geography, 109, 531–539, 2000 (in Japanese with English abstract).

    Article  Google Scholar 

  • Moore, J. C., N. B. Klaus, B. Bekins, C. J. Bucker, W. Bruckmann, S. N. Erickson, O. Hansen, T. Horton, P. Ireland, C. O. Major, G. F. Moore, S. Peacok, S. Saito, E. J. Screaton, J. W. Shimeld, P. H. Stauffer, T. Taymaz, P. A. Teas, and T. Tokunaga, Consolidation patterns during initiation and evolution of plate-boundary decollement zone: Northern Barbados accretionary prism, Geology, 26, 811–814, 1998.

    Article  Google Scholar 

  • NIED Hi-net, Special page for the 2003 Tokachi-Oki earthquake,, 2003.

    Google Scholar 

  • Von Huene, R. and R. Culotta, Tectonic erosion at the front of the Japan Trench convergent margin, Tectonophysics, 160, 75–90, 1989.

    Article  Google Scholar 

  • Wessel, P. and W. H. F. Smith, Free software helps map and display data, Eos Trans. AGU, 72, 445–446, 1991.

    Article  Google Scholar 

  • Yagi, Y., Source rupture process of the Tokachi-oki earthquake of September 26 2003, determined by joint inversion of teleseismic body wave and strong motion data, Earth Planets Space, 56, this issue, 311–316, 2004.

    Article  Google Scholar 

  • Yamanaka, Y. and M. Kikuchi, Source process of the recurrent Tokachi-oki earthquake on September 26, 2003, inferred from teleseismic body waves, Earth Planets Space, 55, e21–e24, 2003.

    Article  Google Scholar 

  • Yamazaki, T. and Y. Okamura, Subducting seamounts and deformation of overriding forearc wedges around Japan, Tectonophysics, 160, 207–229, 1989.

    Article  Google Scholar 

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Correspondence to Kazushige Obara.

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Obara, K., Haryu, Y., Ito, Y. et al. Low frequency events occurred during the sequence of aftershock activity of the 2003 Tokachi-Oki earthquake; a dynamic process of the tectonic erosion by subducted seamount. Earth Planet Sp 56, 347–351 (2004).

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Key words

  • Low-frequency earthquake
  • 2003 Tokachi-Oki earthquake
  • subduction zone
  • tectonic erosion
  • seamount
  • plate boundary