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195
Bull. Earthq. Res. Inst.
Univ. Tokyo
Vol. pp.
* e-mail : [email protected]
Earthquake Research Institute, University of Tokyo, Graduate School of Science, Hokkaido
University, Graduate School of Science, Tohoku University, Graduate School of Science, Nagoya
University, Graduate School of Science, Kyoto University, Disaster Prevention Research Insti-
tute, Kyoto University, Graduate School of Science, Kyushu University, Faculty of Science,
Kagoshima University
A joint dense seismic observation experiment was conducted during the period of September
April in cooperation of researchers of national universities under the national project for
prediction of volcanic eruption. Major objectives include seismic exploration of the subsurface
structure of Fuji volcano and surrounding area as well as array observation of deep low frequency
earthquakes, the activity of which increased in beneath the volcano. We installed seis-
mographs temporarily on and around Fuji volcano and the data was transmitted to the Volcano
Research Center (VRC), Earthquake Research Institute by satellite, radio and cable telemetry sys-
tems. We further collected seismic data of permanent stations around Fuji volcano operated by
related research institutions. All the data was collected and picked at VRC. In this initial report we
describe the brief outline of the joint experiment, and summarize the preliminary results of analyses
on the seismic velocity structure of Fuji volcano and wave characteristics of a low frequency
earthquake, which occurred on September .
: Mt. Fuji, array observation, velocity structure, low frequency earthquake, eruption
prediction
*
Hidefumi Watanabe *, Haruhisa Nakamichi , Takao Ohminato , Tsuneomi Kagiyama ,
Jun Oikawa , Yosuke Aoki , Hiroshi Tsuji , Etsurou Koyama , Noboru Osada , Michi-
nori Hagiwara , Toyotarou Takeda , Masakatsu Kobayashi , Hiromitsu Oshima , Hi-
roshi Aoyama , Tokumitsu Maekawa , Atsuo Suzuki , Satoshi Tanaka , Takeshi
Nishimura , Kouichi Nita , Jun Yamazaki , Takashi Okuda , Mamoru Yamada , Taka-
hiro Okura , Yasuaki Sudo , Shin Yoshikawa , Masato Iguchi , Hiroshi Shimizu , Kenji
Uehira , Ken Matsushima , Hiroshi Yakiwara and Shuichiro Hirano
Abstract
Key words
Japanese University Joint Dense Seismic Observation
on and around Fuji Volcano (September April
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Table . General outline and agreement on the joint dense seismic observation experi-
ment on and around Fuji volcano.
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Table . A list of temporal seismic stations on and around Fuji volcano.
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figure denote seismic stations operated by several institutions as indicated in legend. Solid symbols indicate
the temporal seismic stations operated during the present dense observation experiment. Gray stars are shot
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Fig. . Hypocenter distribution of earthquakes that
occurred around Fuji volcano during the period,
April to October .
Fig. . The results of checkerboard tests for the seis-
mic velocity tomography around Fuji volcano. Hy-
pocenter distribution of earthquakes during the
period of used for the checkerboard tests
(a), and the results for grid spacing of km (b) and
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Fig. . Vertical component velocity seismograms of the low frequency earthquake, which occurred beneath Fuji
volcano at : JST on September . The left side shows unfiltered seismograms and the right side those
obtained after Hz low-pass filtering. Each trace is normalized by its maximum amplitude. Location of seismic
stations is shown in the Figure .
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for the low frequency earthquake, which occurred at : JST on September .
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seismogram observed at HSO (Fig. ).
Fig. . Predominant directions of particle motion
observed around Mt. Fuji for the . Hz component
of the low frequency earthquake at : JST on
September .
Fig. . Band passed seismograms of the vertical
component seismogram observed at HSO (Fig. ).
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onds later (arrow B) after the initial arrival of P
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, .
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MT Aizawa
km
km
Hi-net
J. Geophys. Res.
Tectonophysics,
J. Phys. Earth,
Tectonophysics,
J. Volcanol. Geotherm. Res.
Geophys. J. Int.
EarthPlanets Space,
Geophys. Res. Lett.,
Geophys. Res. Lett,
Tectonophysics,
et
al.,
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. P-wave velocity structure of Bandai volcano in north-
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Yamawaki, T., S. Tanaka, S. Ueki, H. Hamaguchi, H. Naka- Received April ,
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J.Volcanol. Geotherm. Res.,
Bull. Seism. Soc. Amer.,
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