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Resistivity structure around the hypocentral area of the 1984 Western Nagano Prefecture earthquake in central Japan

Earth, Planets and Space volume 54, pages 107–118 (2002)Cite this article

Abstract

We carried out magnetotelluric measurements in the southeastern region of Mt. Ontake, where the 1984 Western Nagano Prefecture earthquake occurred and earthquake swarms have been observed since 1976. Most of the earthquakes have focal depths shallower than 10 km. The depth of the hypocenters increases towards the west. Our purpose is to delineate the resistivity structures down to the focal depths of the earthquakes, because the resistivity structure is very sensitive to the free water in the crust. The regional strike was estimated as N60°E. We carried out a two-dimensional analysis over two profiles across the earthquake fault of the 1984 Western Nagano Prefecture earthquake: one is in the low seismicity region of the fault (A-A′) and the other, in the high seismicity region (B-B′). The resistivity structure along the A-A′ profile is reasonably homogeneous and shows a high resistivity of more than 300 ohm·m. The resistivity structure along the B-B′ profile has a clear boundary at the center of the profile. This boundary divides the structure along the B-B′ profile into two resistivity blocks and its location coincides with that of the earthquake fault. A conductor is detected at depths greater than 8 km to the northwest of the earthquake fault. The depth to the upper boundary of the conductor coincides with those of the seismic reflectors. This structure seems to be formed by the free water dehydrated from the magma.

References

  • Fuji-ta, K., Y. Ogawa, S. Yamaguchi, and K. Yaskawa, Magnetotelluric imaging of the SW Japan forearc, —a lost paleoland revealed?—, Phys. Earth Planet Inter., 102, 231–238, 1997.

    Article  Google Scholar 

  • Gamble, T. D., W. M. Goubau, and J. Clarke, Magnetotellurics with a remote magnetic reference, Geophysics, 44, 53–68, 1979.

    Article  Google Scholar 

  • Geological Survey of Japan, Geological Map of Japan 1:1,000,000, 3rd Edition, CD-ROM Version, Digital Geoscience Map G-1, 1995.

  • Groom, R. W. and R. C. Bailey, Decomposition of magnetotelluric Impedance tensors in the presence of local three dimensional galvanic distortions, J. Geophys. Res., 94, 1913–1925, 1989.

    Article  Google Scholar 

  • Gupta, H. K., S. V. V. Sarma, T. Harinarayana, and G. Virupakshi, Fluids below the hypocentral region of Latur earthquake, India; geophysical indicators, Geophys. Res. Lett., 23, 1569–1572, 1996.

    Article  Google Scholar 

  • Hori, S., H. Aoki, and T. Ooida, Focal mechanisms of the earthquake swarm southeast of Mt. Ontake, Central Honshu, Japan, Zishin, 35, 162–169, 1982 (in Japanese with English abstract).

    Google Scholar 

  • Horiuchi, S. and The members of the 1986 Joint Seismological Research in Western Nagano Prefecture, Hypocenter locations by a dense network, J. Phys. Earth, 40, 313–326, 1992.

    Article  Google Scholar 

  • Iio, Y., R. Ikeda, K. Omura, Y. Matsuda, Y. Shiokawa, M. Takeda, and D. Uehara, Conductivity structure of seismogenic region in the western Nagano prefecture, Butsuri-Tansa, 53, 56–66, 2000.

    Google Scholar 

  • Inamori, T., S. Horiuchi, and A. Hasegawa, Location of mid-crustal reflectors by a reflection method using aftershock waveform data in the focal area of the 1984 Western Nagano Prefecture Earthquake, J. Phys. Earth, 40, 379–393, 1992.

    Article  Google Scholar 

  • Japan Meteorological Agency, The Western Nagano Prefecture Earthquake, 1984, Report of the Coordinating Committee for Earthquake Prediction, 33, 116–128, 1985.

    Google Scholar 

  • Kimura, J. and T. Yoshida, Magma transport system beneath Norikura volcanic chains, Gekkan Chikyu (Earth Monthly), 18, 97–103, 1996 (in Japanese).

    Google Scholar 

  • Miller, C. K. and K. P. Furlong, Thermal-mechanical controls seismicity depth distribution in the San Andreas Fault Zone, Geophys. Res. Lett., 15, 1429–1432, 1988.

    Article  Google Scholar 

  • Mizoue, M. and Y. Ishiketa, Detection of melting zone beneath fault area of the 1984 Western Nagano Prefecture Earthquake and beneath southeastern foot of Mt. Ontake, Gekkan Chikyu (Earth Monthly), 10, 700–705, 1988 (in Japanese).

    Google Scholar 

  • Mizoue, M. and I. Nakamura, Mapping of an unusual crustal discontinuity by microearthquake reflections in the earthquake swarm area near Asio, Northwestern Part of Tochigi Prefecture, Central Japan, Bull. Earthq. Res. Inst., Univ. Tokyo, 57, 653–686, 1982.

    Google Scholar 

  • New Energy and Industrial Technology Development Organization (NEDO), Investigation report of the geothermal development promotion (Otaki area), No. 17, 1988.

  • Ogawa, Y. and T. Uchida, Two dimensional magnetotelluric inversion assuming Gaussian static shift, Geophys. J. Int., 126, 69–76, 1996.

    Article  Google Scholar 

  • Ogawa, Y., Y. Honkura, F. Ohtani, H. Kuroki, and Y. Mitsuhata, Preliminary magnetotelluric modeling in the Nikko Volcanic Area-Potential Break of Fluid Trap by Volcanic Intrusion, J. Geomag. Geoelectr., 49, 1073–1078, 1997.

    Article  Google Scholar 

  • Shichi, R., A. Yamamoto, A. Kimura, and H. Aoki, Gravimetric evidences for active faults around Mt. Ontake, central Japan: Specifically for the hidden faulting of the 1984 Western Nagano Prefecture Earthquake, J. Phys. Earth, 40, 459–478, 1992.

    Article  Google Scholar 

  • Sibson, R. H., Fault zone models, heat flow, and the depth distribution of earthquakes in the continental crust of the United States, Bull. Seism. Soc. Am., 72, 151–163, 1982.

    Google Scholar 

  • Swift, C. M., A magnetotelluric investigation of an electrical conductivity anomaly in the southern United States, Ph.D. thesis, Dept. of Geol. and Geophy., Mass. Inst. of Technol., Cambridge, 1967.

    Google Scholar 

  • Takakura, S., M. Takeda, and K. Matsuo, Effects of regional noise on magnetotellurics and their removal by far remote reference method, Butsuri-Tansa (Geopys. Explor.), 47, 24–35, 1994.

    Google Scholar 

  • Takeda, J., Y. Iio, Y. Kobayashi, K. Yamamoto, H. Sato, S. Ohmi, H. Ito, R. Ikeda, and E. Yamamoto, The Relationship between seismicity and fluid existing in the crust inferred from Vp/Vs Ratio, Zisin, 51, 419–430, 1999 (in Japanese with English abstract).

    Google Scholar 

  • Tanabe, S., Time variation in seismic reflector around Mt. Ontake, M.Sc. Thesis, Earth and Planetary Science, Kyoto Univ., 40 pp., 1996.

  • Ting, S. C. and G. W. Hohmann, Integral equation modeling of three dimensional magnetotelluric response, Geophysics, 46, 192–197, 1981.

    Article  Google Scholar 

  • Umeda, Y. and K. Ito, A model for the prediction of intraplate large earthquake growing in the inhomogeneous crust, Zisin, 50, 263–272, 1998 (in Japanese with English abstract).

    Google Scholar 

  • Yamada, N. and T. Kobayashi, Geology of the Ontakesan district. Geological Sheet Map at 1:50,000, Geological. Survey. Japan, 136 p., 1988 (in Japanese with English abstract).

  • Yamashina, K. and T. Tada, A fault model of the 1984 Western Nagano Prefecture Earthquake based on the distance change, Bull. Earthq. Res. Inst., Univ. Tokyo, 60, 221–230, 1985.

    Google Scholar 

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Author notes

  1. Yoshihisa Iio

    Present address: Earthquake Research Institute, The University of Tokyo, Tokyo, 113-0032, Japan

  2. Norihiko Sumitomo

    Present address: Faculty of Humanities and Sciences, Kobe Gakuin University, Nishiku, Kobe, 651-2180, Japan

Authors and Affiliations

  1. Disaster Prevention Research Institute, Kyoto University, Kyoto, 611-0011, Japan

    Takafumi Kasaya, Naoto Oshiman & Norihiko Sumitomo

  2. Earthquake Research Institute, The University of Tokyo, Tokyo, 113-0032, Japan

    Makoto Uyeshima

  3. National Research Institute for Earth Science and Disaster Prevention, Tennodai 3-1, Tsukuba, 305-0006, Japan

    Yoshihisa Iio

  4. Sumiko Consultants CO. LTD., Tokyo, 166-0021, Japan

    Daijiro Uehara

Authors
  1. Takafumi Kasaya
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  2. Naoto Oshiman
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  3. Norihiko Sumitomo
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  4. Makoto Uyeshima
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  5. Yoshihisa Iio
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  6. Daijiro Uehara
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Correspondence to Takafumi Kasaya.

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Kasaya, T., Oshiman, N., Sumitomo, N. et al. Resistivity structure around the hypocentral area of the 1984 Western Nagano Prefecture earthquake in central Japan. Earth Planet Sp 54, 107–118 (2002). https://doi.org/10.1186/BF03351711

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