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A tectonic interpretation of NW-SE strike-slip faulting during the 2004 off the Kii peninsula earthquakes, Japan: Probable tear of the Philippine Sea plate

Earth, Planets and Space volume 57, pages 1115–1120 (2005)Cite this article

Abstract

The 2004 off the Kii peninsula earthquakes (Mw 7.5 for the main shock) occurred within the subducting Philippine Sea (PHS) plate near its boundary, the Nankai trough, southwest Japan. The rupture mode of the foreshock-main shock-aftershock sequence was complicated, a combination of ENE-WSW striking (almost trough parallel) reverse faulting beneath the trough and NW-SE trending (almost trough normal) strike-slip faulting mostly on the landward side of the former. In this paper, we discuss the tectonic meaning of this NW-SE running strike-slip fault. We examined hypocenter distribution and focal mechanisms of slab earthquakes from October 1997 through September 2004 and confirmed a NW-SE striking tear of the PHS slab beneath the middle part of the Kii Peninsula pointed out by Miyoshi and Ishibashi (2004). According to the Earthquake Research Committee (2004) there is a NW-SE trending structural discontinuity in the PHS crust to the southeast of the main shock epicenter. Putting all features together, we interpret that there is a NW-SE striking fracture within the PHS plate continuously from the Nankai trough region to the slab beneath the Kii Peninsula, and that a partial rupture of this fracture occurred during the off the Kii peninsula earthquakes together with trough-parallel reverse faulting. It should be noted that two disastrous M 7-class slab earthquakes seem to have occurred along this tear beneath the peninsula in 1899 and 1952.

References

  • Ando, M., Source mechanisms and tectonic significance of historical earthquakes along the Nankai trough, Japan, Tectonophysics, 27, 119–140. 1975.

    Article  Google Scholar 

  • Baba, T., P. R. Cummins, and T. Hori, Compound fault rupture during the 2004 off the Kii Peninsula earthquake (M7.4) inferred from highly resolved coseismic sea-surface deformation, Earth Planets Space, 57, 167–172, 2005.

    Article  Google Scholar 

  • Earthquake Research Committee, Headquarters for Earthquake Research Promotion, On the long-term evaluation of earthquakes along the Nankai trough (September 27, 2001), http://www.jishin.go.jp/main/index.html, 2001 (in Japanese).

    Google Scholar 

  • Earthquake Research Committee, Headquarters for Earthquake Research Promotion, Seismic activity off-shore southeast of the Kii Peninsula (October 13, 2004), http://www.jishin.go.jp/main/index-e.html, 2004.

    Google Scholar 

  • Hara, T., Change of the source mechanism of the main shock of the 2004 off the Kii peninsula earthquakes inferred from long period body wave data, Earth Planets Space, 57, 179–183, 2005.

    Article  Google Scholar 

  • Hashimoto, M., K. Onoue, F. Ohya, Y. Hoso, K. Segawa, K. Sato, and Y. Fujita, Crustal deformations in Kii peninsula associated with the SE off the Kii peninsula earthquake sequence of September 5, 2004 derived from dense GPS observations, Earth Planets Space, 57, 185–190, 2005.

    Article  Google Scholar 

  • Ito, Y., T. Matsumoto, H. Kimura, H. Matsubayashi, K. Obara, and S. Sekiguchi, Spatial distribution of centroid moment tensor solutions for the 2004 off Kii peninsula earthquakes, Earth Planets Space, 57, 351–356, 2005.

    Article  Google Scholar 

  • Kikuchi, M., M. Nakamura, and K. Yoshikawa, Source process of the Yoshino earthquake of July 18, 1952, inferred from low-gain seismo-grams, Abstracts of the 2002 Japan Earth and Planetary Science Joint Meeting (CD-ROM), S051–001, 2002 (in Japanese with English abstract).

    Google Scholar 

  • Miyoshi, T. and K. Ishibashi, Geometry of the seismic Philippine Sea slab beneath the region from Ise Bay to western Shikoku, southwest Japan, Zisin (J. Seism. Soc. Jpn.), Second Ser., 57, 139–152, 2004 (in Japanese with English abstract).

    Google Scholar 

  • Park, S. C. and J. Mori, The 2004 sequence of triggered earthquakes off the Kii peninsula, Japan, Earth Planets Space, 57, 315–320, 2005.

    Article  Google Scholar 

  • Sakai, S., T. Yamada, M. Shinohara, H. Hagiwara, T. Kanazawa, K. Obana, S. Kodaira, and Y. Kaneda, Urgent aftershock observation of the 2004 off the Kii Peninsula earthquake using ocean bottom seismometers, Earth Planets Space, 57, 363–368, 2005.

    Article  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 

  • Seno, T., The September 5, 2004 off the Kii Peninsula earthquakes as a composition of bending and collision, Earth Planets Space, 57, 327–332, 2005.

    Article  Google Scholar 

  • Utsu, T., Seismicity of Japan from 1885 through 1925-A new catalog of earthquakes of M ≥ 6 felt in Japan and smaller earthquakes which caused damage in Japan, Bull. Earthq. Res. Inst., Univ. Tokyo, 54, 253–308, 1979 (in Japanese with English abstract).

    Google Scholar 

  • Utsu, T., Relationships between magnitude scales, in International Handbook of Earthquake and Engineering Seismology, Part A, IASPEI, edited by W. H. K. Lee, H. Kanamori, P. C. Jennings, and C. Kisslinger, pp. 733–746, Academic Press, New York, 2002 (Full manuscript is given in Utsu3FullManuscript.pdf on the attached Handbook CD #1, directory/44Utsu3).

    Chapter  Google Scholar 

  • Wessel, P. and W. H. F. Smith, New version of the Generic Mapping Tools released, EOS Trans. Am. Geophys. Union, 76, 329, 1995.

    Article  Google Scholar 

  • Yagi, Y., On the earthquakes which occurred southeast-off the Kii Peninsula on September 5, 2004, http://iisee.kenken.go.jp/staff/yagi/eq/Japan20040905/Japan200409051-j.html, 2004 (in Japanese).

    Google Scholar 

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Authors and Affiliations

  1. Graduate School of Science and Technology, Kobe University, Kobe, 657-8501, Japan

    Takayuki Miyoshi

  2. Research Center for Urban Safety and Security, Kobe University, Kobe, 657-8501, Japan

    Katsuhiko Ishibashi

Authors
  1. Takayuki Miyoshi
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  2. Katsuhiko Ishibashi
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Correspondence to Takayuki Miyoshi.

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Miyoshi, T., Ishibashi, K. A tectonic interpretation of NW-SE strike-slip faulting during the 2004 off the Kii peninsula earthquakes, Japan: Probable tear of the Philippine Sea plate. Earth Planet Sp 57, 1115–1120 (2005). https://doi.org/10.1186/BF03351891

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  • DOI: https://doi.org/10.1186/BF03351891

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