Skip to main content

Volume 52 Supplement 11

Special Issue: Application of GPS and other space geodetic techniques to Earth Sciences (2)

Crustal deformation associated with the 1998 seismo-volcanic crisis of Iwate Volcano, Northeastern Japan, as observed by a dense GPS network


Mt. Iwate (2,038 m) is an active volcano located in northeastern Japan. Unrest of the volcano started in September, 1995 with intermediate-depth tremors. The shallow seismicity gradually became active in February, 1998, accompanying the notable crustal deformation observed by a dense GPS network. The pattern of the horizontal displacements is characterized by radially directing outward from the volcano. We estimated the source position by inversion analyses for every two-months period, assuming two models; a point pressure source (Mogi model) and a tensile fault. The comparison of AIC’s for the two models indicates that the latter is proper from February to April, while the former is preferable afterward. The tensile fault was located at about 5 km WSW of the summit and 3 km in depth, then a Mogi source was estimated at the western neighbor of the tensile fault in the successive period and moved westward as far as 10 km W of the summit with shallowing its depth. It should be noted that the seismic area also expanded westward in the same period. This synchronicity suggests that the both phenomena were caused by a movement of magma from the deeper part beneath the summit to the western shallower part.


  • Geographical Survey Institute, Volcanic and seismic crustal deformations of Mt. Iwate detected by the JERS-1 synthetic aperture radar (SAR) interferometry, Rep. Coord. Commit. Earthq. Pred., 61, 86–90, 1999 (in Japanese).

    Google Scholar 

  • Kimata, F., H. Mori, A. Suzuki, M. Sato, S. Ueki, H. Hamaguchi, H. Tsuji, A. Terada, E.Koyama, T.Takeda, H. Watanabe, R. Miyajima, M. Nakabo, T. Takayama, K. Yamamoto, K. Ishihara, K. Uchida, K. Matsushima, H. Yakiwara, and F. Hirano, Vertical crustal movement at the southern foot of Mount Iwate deduced by leveling survey, Chikyu, 21, 302–306, 1999 (in Japanese).

    Google Scholar 

  • Koshiya, S., M. Oishi, M. Noda, Y. Okudera, T. Kato, S. Takiguchi, Y. Mitachi, M. Shimamori, T. Saito, K. Yanai, S. Hirano, H. Sawa, T. Fukudome, H. Sato, K. Otsuki, H. Nagahama, N. Nakamura, N. Doi, M. Togo, Y. Awata, and T. Yoshioka, Earthquake fault with the Iwate-ken Nairiku-hokubu earthquake of September 3, 1998, Active Fault Res., 17, 9–20, 1998 (in Japanese with an English abstract).

    Google Scholar 

  • Matsu’ura, M. and Y. Hasegawa, A maximum likelihood approach to nonlinear inversion under constraints, Phys. Earth Planet. Inter., 47, 179–187, 1987.

    Article  Google Scholar 

  • Miyazaki, S., T. Saito, M. Sasaki, Y. Hatanaka, and Y. Iimura, Expansion of GSI’s nationwide GPS array, Bull. Geogr. Surv. Inst., 43, 23–34, 1997.

    Google Scholar 

  • Mogi, K., Relations between the eruptions of various volcanoes and the deformations of the ground surfaces around them, Bull. Earthquake Res. Inst. Tokyo, 36, 99–134, 1958.

    Google Scholar 

  • National Space Development Agency of Japan and Nagoya University, Ground deformation activities detected by differential interferometric SAR using JERS-1/SAR around Iwate Volcano, Rep. Coord. Commit. Earthq. Pred., 61, 94–96, 1999 (in Japanese).

    Google Scholar 

  • Nishimura, T., H. Nakamichi, S. Tanaka, M. Sato, T. Kobayashi, S. Ueki, H. Hamaguchi, M. Ohtake, and H. Sato, Source process of very long period seismic events associated with the 1998 activity of Iwate Volcano, northeastern Japan, J. Geophys. Res., 105, 19,135–19,148, 2000.

    Article  Google Scholar 

  • Okada, Y., Internal deformation due to shear and tensile faults in a half-space, Bull. Seism. Soc. Am., 82, 1018–1040, 1992.

    Google Scholar 

  • Saito, M., An automatic design algorithm for band selective recursive digital filters, Butsuri-Tanko (Geophys. Explor.), 31, 112–135, 1978 (in Japanese with an English abstract).

    Google Scholar 

  • Sato, M. and H. Hamaguchi, Analysis of crustal deformation around Iwate volcano for the period from February to August, 1998, Chikyu, 21, 312–317, 1999 (in Japanese).

    Google Scholar 

  • Tanaka, S., H. Nakamichi, H. Hamaguchi, and S. Ueki, The 1998 seismic activity of Mount Iwate, Chikyu, 21, 273–279, 1999 (in Japanese).

    Google Scholar 

  • Tanaka, S., H. Hamaguchi, S. Ueki, M. Sato, and H. Nakamichi, Migration of seismic activity during the 1998 volcanic unrest at Iwate volcano, northeastern Japan, with reference to P and S wave velocity anomaly and crustal deformation, J. Volcanol. Geotherm. Res., 2000 (in press).

  • Ueki, S., An attempt to identify the intruded material that caused the 1998 volcanic crisis of Iwate Volcano, EOS Trans. Amer Geophys. U., 81(22), 234, 2000.

    Google Scholar 

  • Ueki, S., Y. Morita, and H. Hamaguchi, On the volcanic tremor observed at Iwate Volcano in September and October, 1995, Tohoku J. Natural Disas. Sci., 32, 285–292, 1996 (in Japanese).

    Google Scholar 

  • Ueki, S., S. Miura, T. Sato, K. Tachibana, and H. Hamaguchi, Crustal deformation around Iwate volcano, Chikyu, 21, 296–301, 1999 (in Japanese).

    Google Scholar 

  • Umino, N., T. Okada, A. Nakamura, J. Nakajima, T. Sato, S. Hori, T. Kono, K. Nida, S. Ueki, T. Matsuzawa, A. Hasegawa, and H. Hamaguchi, Aftershock distribution for the M6.1 earthquake of 3 September 1998 in Shizukuishi, Iwate prefecture, northeastern Japan, Active Fault Res., 17, 1–8, 1998 (in Japanese with an English abstract).

    Google Scholar 

Download references

Author information

Authors and Affiliations


Corresponding author

Correspondence to Satoshi Miura.

Rights and permissions

Reprints and Permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Miura, S., Ueki, S., Sato, T. et al. Crustal deformation associated with the 1998 seismo-volcanic crisis of Iwate Volcano, Northeastern Japan, as observed by a dense GPS network. Earth Planet Sp 52, 1003–1008 (2000).

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:


  • Synthetic Aperture Radar
  • Crustal Deformation
  • Fault Parameter
  • Pressure Source
  • Coseismic Displacement