Aftershock distribution of the 2004 Mid Niigata Prefecture Earthquake derived from a combined analysis of temporary online observations and permanent observations

Takuo Shibutani, Yoshihisa Iio, Satoshi Matsumoto, Hiroshi Katao, Takeshi Matsushima, Shiro Ohmi, Fumiaki Takeuchi, Kenji Uehira, Kin'ya Nishigami, Bogdan Enescu, Issei Hirose, Yasuyuki Kano, Yuhki Kohno, Masahiro Korenaga, Yutaka Mamada, Masatoshi Miyazawa, Ken'ichi Tatsumi, Tomotake Ueno, Hiroo Wada, Yohei Yukutake

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34 Citations (Scopus)

Abstract

The 2004 Mid Niigata Prefecture Earthquake (Mj = 6.8) occurred on 23 October 2004 in the northeastern part of the Niigata-Kobe Tectonic Zone where large contraction rates were observed. The mainshock was followed by an anomalously intense aftershock activity that included nine Mj ≥ 5.5 aftershocks. We deployed three temporary online seismic stations in the aftershock area from 27 October, combined data from the temporary stations with those from permanent stations located around the aftershock area, and determined the hypocenters of the mainshock and aftershocks with a joint hypocenter determination (JHD) technique. The resulting aftershock distribution showed that major events such as the mainshock, the largest aftershock (Mj = 6.5), the aftershock on 27 October (Mj = 6.1), etc. occurred on different fault planes that were located nearly parallel or perpendicular to each other. This might be due to heterogeneous structure in the source region. The strain energy was considered to have been enough accumulated on the individual fault planes. These features are probably a cause of the anomalous intensity of the aftershock activity.

Original languageEnglish
Pages (from-to)545-549
Number of pages5
Journalearth, planets and space
Volume57
Issue number6
DOIs
Publication statusPublished - Jan 1 2005

All Science Journal Classification (ASJC) codes

  • Geology
  • Space and Planetary Science

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    Shibutani, T., Iio, Y., Matsumoto, S., Katao, H., Matsushima, T., Ohmi, S., Takeuchi, F., Uehira, K., Nishigami, K., Enescu, B., Hirose, I., Kano, Y., Kohno, Y., Korenaga, M., Mamada, Y., Miyazawa, M., Tatsumi, K., Ueno, T., Wada, H., & Yukutake, Y. (2005). Aftershock distribution of the 2004 Mid Niigata Prefecture Earthquake derived from a combined analysis of temporary online observations and permanent observations. earth, planets and space, 57(6), 545-549. https://doi.org/10.1186/BF03352590