Skip to main content

Advertisement

We’d like to understand how you use our websites in order to improve them. Register your interest.

Shear wave polarization anisotropy in and around the focal region of the 2005 West off Fukuoka Prefecture earthquake

Abstract

Crustal shear wave polarization anisotropy is caused by the alignment of vertical microcracks. Leading shear wave polarization directions (LSPDs) are presumed to be consistent with the maximum horizontal compressional axis in many cases. We analyzed shear wave polarization anisotropy in and around the focal region of the 2005 West off Fukuoka Prefecture earthquake. Almost all of the LSPDs are oriented in the E-W direction, which is consistent with the maximum horizontal compressional axis inferred from the mechanism of the main shock. These E-to W-oriented LSPDs are caused by the alignment of stress-induced microcracks. Crack densities at most stations are estimated to be 0.02. Little spacial stress variation around focal region is suspected

References

  1. Crampin, S., Seismic wave propagation through a cracked solid: Polarization as a possible dilatancy diagnostic, Geophys. J. R. Astron. Soc., 53, 467–496, 1978.

    Article  Google Scholar 

  2. Crampin, S., A review of wave motion in anisotropic and cracked elastic-media, Wave Motion, 3, 343–391, 1981.

    Article  Google Scholar 

  3. Crampin, S., Evaluation of anisotropy by shear-wave splitting, Geophysics, 50, 142–152, 1985.

    Article  Google Scholar 

  4. Crampin, S., D. C. Booth, R. Evans, S. Peacock, and J. B. Fletcher, Changes in shear wave splitting at Anza near the time of the North Plam Springs Earthquake, J. Geophys. Res., 95, 11,197–11,212, 1990.

    Article  Google Scholar 

  5. Hori, M., S. Matsumoto, K. Uehira, T. Okada, T. Yamada, Y. Iio, M. Shinohara, H. Miyamachi, H. Takahashi, K. Nakahigashi, A. Watanabe, T. Matsushima, N. Matsuwo, T. Kanazawa, and H. Shimizu, Three-dimensional seismic velocity structure as determined by double-difference tomography in and around the focal area of the 2005 West off Fukuoka Prefecture earthquake, Earth Planets Space, 58, this issue, 1621–1626, 2006.

    Article  Google Scholar 

  6. Imanishi, K., Y. Kuwahara, and Y. Haryu, Off-fault aftershocks of the 2005 West Off Fukuoka Prefecture Earthquake: Reactivation of a structural boundary?, Earth Planets Space, 58, 81–86, 2006.

    Article  Google Scholar 

  7. Johnson, P. A. and P. N. J. Rasolofosaon, Nonlinear elasticity and stress-induced anisotropy in rock, J. Geophys. Res., 101, 3113–3124, 1996.

    Article  Google Scholar 

  8. Kaneshima, S., Origin of crustal anisotropy: Shear wave splitting studies in Japan, J. Geophys. Res., 95, 11,121–11,134, 1990.

    Article  Google Scholar 

  9. Karakida, Y., S. Tomita, S. Shimoyama, and K. Chijiwa, Geological Sheet Map 1:50,000 “Fukuoka”, Geological Survey of Japan, 1994.

    Google Scholar 

  10. Mizuno, T., K. Yomogida, H. Ito, and Y. Kuwahara, Spatial distribution of shear wave anisotropy in the crust of the southern Hyogo region by borehole observations, Geophys. J. Int., 147, 528–542, 2001.

    Article  Google Scholar 

  11. Nishimura, T., S. Fujiwara, M. Murakami, H. Suito, M. Tobita, and H. Yarai, Fault model of the 2005 Fukuoka-ken Seiho-oki earthquake estimated from coseismic deformation observed by GPS and InSAR, Earth Planets Space, 58, 51–56, 2006.

    Article  Google Scholar 

  12. Saiga, A., Y. Hiramatsu, T. Ooida, and K. Yamaoka, Spatial variation in the crustal anisotropy and its temporal variation associated with a moderate-size earthquake in the Tokai region, central Japan, Geophys. J. Int., 154, 695–705, 2003.

    Article  Google Scholar 

  13. Shimizu, H., H. Takahashi, T. Okada, T. Kanazawa, Y. Iio, H. Miyamachi, T. Matsushima, M. Ichiyanagi, N. Uchida, T. Iwasaki, H. Katao, K. Goto, S. Matsumoto, N. Hirata, S. Nakao, K. Uehira, M. Shinohara, H. Yakiwara, N. Kame, T. Urabe, N. Matsuwo, T. Yamada, A. Watanabe, K. Nakahigashi, B. Enescu, K. Uchida, S. Hashimoto, S. Hirano, T. Yagi, Y. Kohno, T. Ueno, M. Saito, and M. Hori, Aftershock seismicity and fault structure of the 2005 West Off Fukuoka Prefecture Earthquake (MJMA7.0) derived from urgent joint observations, Earth Planets Space, 58, this issue, 1599–1604, 2006.

    Article  Google Scholar 

  14. Tadokoro, K., M. Ando, and Y. Umeda, S wave splitting in the aftershock region of the 1995 Hyogoken Nanbu earthquake, J. Geophys. Res., 104, 981–992, 1999.

    Article  Google Scholar 

  15. Tadokoro, K. and M. Ando, Evidence for rapid fault healing derived from temporal changes in S wave splitting, Geophys. Res. Lett., 29, 10.1029/2001GL013644, 2002.

  16. Takenaka, H., T. Nakamura, Y. Yamamoto, G. Toyokuni, and H. Kawase, Precise location of the fault plane and the onset of the main rupture of the 2005 West Off Fukuoka Prefecture earthquake, Earth Planets Space, 58, 75–80, 2006.

    Article  Google Scholar 

  17. Uehira, K., T. Yamada, M. Shinohara, K. Nakahigashi, H. Miyamachi, Y. Iio, T. Okada, H. Takahashi, N. Matsuwo, K. Uchida, T. Kanazawa, and H. Shimizu, Precise aftershock distribution of the 2005 West Off Fukuoka Prefecture Earthquake (Mj=7.0) using a dense onshore and offshore seismic network, Earth Planets Space, 58, this issue, 1605–1610, 2006.

    Article  Google Scholar 

Download references

Author information

Affiliations

Authors

Corresponding author

Correspondence to Atsushi Watanabe.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Watanabe, A., Matsumoto, S., Matsushima, T. et al. Shear wave polarization anisotropy in and around the focal region of the 2005 West off Fukuoka Prefecture earthquake. Earth Planet Sp 58, 1633–1636 (2006). https://doi.org/10.1186/BF03352674

Download citation

Key words

  • Shear wave polarization anisotropy
  • 2005 West off Fukuoka earthquake