- Open Access
Shear wave polarization anisotropy in and around the focal region of the 2005 West off Fukuoka Prefecture earthquake
Earth, Planets and Space volume 58, pages 1633–1636 (2006)
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
Crampin, S., Seismic wave propagation through a cracked solid: Polarization as a possible dilatancy diagnostic, Geophys. J. R. Astron. Soc., 53, 467–496, 1978.
Crampin, S., A review of wave motion in anisotropic and cracked elastic-media, Wave Motion, 3, 343–391, 1981.
Crampin, S., Evaluation of anisotropy by shear-wave splitting, Geophysics, 50, 142–152, 1985.
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.
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.
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.
Johnson, P. A. and P. N. J. Rasolofosaon, Nonlinear elasticity and stress-induced anisotropy in rock, J. Geophys. Res., 101, 3113–3124, 1996.
Kaneshima, S., Origin of crustal anisotropy: Shear wave splitting studies in Japan, J. Geophys. Res., 95, 11,121–11,134, 1990.
Karakida, Y., S. Tomita, S. Shimoyama, and K. Chijiwa, Geological Sheet Map 1:50,000 “Fukuoka”, Geological Survey of Japan, 1994.
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.
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.
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.
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.
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.
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.
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.
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.
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
- Shear wave polarization anisotropy
- 2005 West off Fukuoka earthquake