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High-resolution aftershock observations in the source region of the 2004 mid-Niigata Prefecture Earthquake


We deployed an extremely dense temporal seismic network in the source region of the 2004 mid-Niigata Prefecture Earthquake (thrust fault) on October 23, 2004, Japan. The seismic network consisted of 145 temporary seismic stations within a 30 km squared and had been kept within approximately a month after the mainshock. High accurate hypocenters of 708 events were determined by inverting the arrival times using double-difference earthquake location algorithm. The aftershocks along the mainshock (Mw = 6.6) and the largest aftershock (Mw = 6.3) rupture zones are distributed on two 60° westward-dipping planes, located approximately 5 km apart. Conversely, the Oct. 27 aftershock (Mw = 5.8) occurred on an eastward dipping plane with a dip angle of 25° that was conjugate to the mainshock fault plane. Most of aftershocks at both northeastern and southwestern edges occurred at shallow depths with eastward-dipping planes. Epicenters of aftershocks in the southwestern region are aligned along N15°E, and rotate approximately 20° counterclockwise from the strike of the mainshock fault. This rotation of the aftershock alignments coincides with the rotation of anticline axes in the southwestern area of the source region. Furthermore, distributions of station corrections for a one-dimensional velocity model suggest that the seismic velocity at the western side of the Muikamachi-fault is lower than that at the eastern side. It is also inferred that the velocity structures in the hangingwall vary along the fault strike. The average velocity in the mainshock rupture area is higher than the periphery in the hangingwall, especially compared with the southwestern side of the hypocenter.


  • Aoki, S., M. Nishi, K. Nakamura, T. Hashimoto, S. Yoshikawa, and H. M. Ito, Multi-planar structures in the aftershock distribution of the Mid Niigata prefecture Earthquake in 2004, Earth Planets Space, 57, 411–416, 2005.

    Article  Google Scholar 

  • Hikima, K. and K. Koketsu, Rupture processes of the 2004 Chuetsu (mid-Niigata prefecture) earthquake, Japan: A series of events in a complex fault system, Geophys. Res. Lett., 32, L18303, doi:10.1029/2005GL023588, 2005.

    Article  Google Scholar 

  • Hirata, N. and M. Matsu’ura, Maximum-likelihood estimation of hypocenter with origin time eliminated using nonlinear inversion technique, Phys. Earth Planet. Inter., 47, 50–61, 1987.

    Article  Google Scholar 

  • Kato, A., E. Kurashimo, N. Hirata, T. Iwasaki, and T. Kanazawa, Imaging the source region of the 2004 Mid-Niigata prefecture earthquake and the evolution of a seismogenic thrust-related fold, Geophys. Res. Lett., 32, L07307, doi:10.1029/2005GL022366, 2005a.

    Article  Google Scholar 

  • Kato, A., S. Sakai, N. Hirata, E. Kurashimo, S. Nagai, T. Iidaka, T. Igarashi, Y. Yamanaka, S. Murotani, T. Kawamura, T. Iwasaki, T. Kanazawa, Short-term spatiotemporal variations in the aftershock sequence of the 2004 mid-Niigata prefecture earthquake, Earth Planets Space, 57, 551–556, 2005b.

    Article  Google Scholar 

  • Matsumoto, S., Y. Iio, T. Matsushima, K. Uehira, and T. Shibutani, Imaging of S-wave reflectors in and around the hypocentral area of the 2004 mid Niigata Prefecture Earthquake (M6.8), Earth Planets Space, 57, 557–561, 2005.

    Article  Google Scholar 

  • Okada, T., N. Umino, T. Matsuzawa, J. Nakajima, N. Uchida, T. Nakayama, S. Hirahara, T. Sato, S. Hori, T. Kono, Y. Yabe, K. Ariyoshi, S. Gamage, J. Shimizu, J. Suganomata, S. Kita, S. Yui, M. Arao, S. Hondo, T. Mizukami, H. Tsushima, T. Yaginuma, A. Hasegawa, Y. Asano, H. Zhang, and C. Thurber, Aftershock distribution and 3D seismic velocity structure in and around the focal area of the 2004 mid Niigata prefecture earthquake obtained by applying double-difference tomography to dense temporary seismic network data, Earth Planets Space, 57, 435–440, 2005.

    Article  Google Scholar 

  • Sakai, S., N. Hirata, A. Kato, E. Kurashimo, T. Iwasaki, and T. Kanazawa, Multi-fault system of the 2004 Mid-Niigata Prefecture Earthquake and its aftershocks, Earth Planets Space, 57, 417–422, 2005.

    Article  Google Scholar 

  • Sato, H., The relationship between late Cenozoic tectonic events and stress field and basin development in northeast Japan, J. Geophys. Res., 99, 22261–22274, 1994.

    Article  Google Scholar 

  • Schaff, P. D., G. H. R. Bokelmann, W. L. Ellsworth, E. Zanzerkia, F. Waldhauser, and G. C. Beroza, Optimizing correlation techniques for improved earthquake location, Bull. Seismol. Soc. Am., 94, 705–721, 2004.

    Article  Google Scholar 

  • Shearer, P., Improving local earthquake locations using the L1 norm and waveform cross correlation: application to the Whittier Narrows, California, aftershock sequence, J. Geophys. Res., 102, 8269–8283, 1997.

    Article  Google Scholar 

  • Shibutani, T., Y. Iio, S. Matsumoto, H. Katao, T. Matsushima, S. Ohmi, F. Takeuchi, K. Uehira, K. Nishigami, B. Enescu, I. Hirose, Y. Kano, Y. Kohno, M. Korenaga, Y. Mamada, M. Miyazawa, K. Tatsumi, T. Ueno, H. Wada, and Y. Yukutake, Aftershock distribution of the 2004 Mid Niigata Prefecture Earthquake derived from a combined analysis of temporary online observations and permanent observations, Earth Planets Space, 57, 545–549, 2005.

    Article  Google Scholar 

  • Takeda, T., H. Sato, T. Iwasaki, N. Matsuta, S. Sakai, T. Iidaka, and A. Kato, Crustal structure in the northern Fossa Magna region, central Japan, from refraction/wide-angle reflection data, Earth Planets Space, 56, 1293–1299, 2004.

    Article  Google Scholar 

  • Takeda, T., K. Yanagisawa, T. Sakai, R. Miyawaki, A. Miyawaki, M. Momose, S. Mukoyama, and H. Sasaki, Active geological structure and landforms in epicentral region of the mid Niigata prefecture earthquake in 2004, Zisin, 2nd Ser., 58, 413–426, 2006.

    Google Scholar 

  • Urabe, T., A proposal for a common format for multi-channel seismic wave data, Prog. Abstr. Seismol. Soc. Jpn., 2, 384, 1994.

    Google Scholar 

  • Waldhauser, F. and W. L. Ellsworth, A double-difference earthquake location algorithm: Method and application to the Northern Hayward fault, Bull. Seismol. Soc. Am., 90, 1353–1368, 2000.

    Article  Google Scholar 

  • Wessel, P. and W. H. F. Smith, New version of the generic mapping tools released, Eos Trans. AGU, 76, 329, 1995.

    Article  Google Scholar 

  • Yanagisawa, Y., I. Kobayashi, K. Takeuchi, M. Tateishi, K. Chihara, and H. Kato, Geological Sheet Map 1:50,000 “Ojiya”, Geological Survey of Japan, 1986.

    Google Scholar 

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Correspondence to Aitaro Kato.

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Kato, A., The Research Team of aftershock observations for the 2004 mid-Niigata Prefecture Earthquake. High-resolution aftershock observations in the source region of the 2004 mid-Niigata Prefecture Earthquake. Earth Planet Sp 59, 923–928 (2007).

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Key words

  • Mid-Niigata Prefecture Earthquake
  • aftershocks
  • hypoDD
  • station corrections
  • dense seismic observations