vol. pp. 2, ,**1 +3/ ,*1 ,**, 3

13
腄腆 膟腜膝膧腜腞膳膋 膟腜膔腖膖膄腡腛腻 膭腕膡膔腖膔腖腏膹腖腡腛腓 膟膭膔腖膔腖腏膹腖腡腛腓 膯腥腒膔腖膔 腖腏膹腖腡腛腓 腜膝膔腖膔腖腏膹腖腡腛腓 腜膝膔腖膬腭腡腛腻 腝腷膔腖膔腖腏膹腖腡腛腏 腵腳膞膔腖膹腖膦 膜膩腸膧 膘膡腴腙 膔膮膺膶 腣腯腫膃 腚膎 膍膱膸腔 腽腯 腐膽 膙膛 膤腤膡膢 膗膛膫膓膽 腽膻膕腼 膔膞腪腧 膍腯 膏膎膢 膼膱膣膋 膛膘 膌膒膓腲 膆膛腦腱 腯腮 腑膛 腯膛 膔膐腟腩 膇膠膴膰 腘膎 腍腨膉膅 膊膈 膁膨腢腰 膀膞 膥膱腤 膨膲腹腎膽 腏腈腇腂腋腃腆腍腑腐腌腉腄腊 ῌῌ 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 ) + , - . / 0 1 2 + , - . / 0 1 2 + + + + + + + + + + + + , , , , - - - - . . / / / 0 1 1 1 2 2 + + + + + + + + + + + + , , , , - - - - . . / / / 0 1 1 1 2 2 2, ,**1 +3/ ,*1 ++- **-, +++ ,**, ,**/ ,*** ,**+ ,2 ++ ,**- ,**, 3 ,**/ . ,**, ,**/

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Page 1: Vol. pp. 2, ,**1 +3/ ,*1 ,**, 3

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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.

Fig. . Location map of the dense seismic observation network around Fuji volcano. The various symbols in the

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

points of the seismic exploration experiment in .

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mic velocity tomography around Fuji volcano. Hy-

pocenter distribution of earthquakes during the

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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 .

Fig. . Vertical component velocity seismogram and its running spectra observed at the station HSO

for the low frequency earthquake, which occurred at : JST on September .

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Fig. . Predominant directions of particle motion

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component seismogram observed at HSO (Fig. ).

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South Fossa Magna, central Japan, , ,

, .

Kanjo, K., I. Karakama and R.S. Matsuura, , Seismic

activities of Mt. Fuji region detected by continuous ob-

servation of micro-earthquakes, ,

.

Lees, J.M. and M. Ukawa, , The South Fossa Magna,

Japan, revealed by high-resolution P- and S-wave

travel time tomography, , .

Nakamichi, H., S. Tanaka and H. Hamaguchi, , Fine S

wave velocity structure beneath Iwate volcano, north-

eastern Japan, as derived from receiver functions and

travel times, , , .

Nakamichi, H., H. Hamaguchi, S, Tanaka, S. Ueki, T. Nishi-

mura and A. Hasegawa, , Source mechanisms of

deep and intermediate-depth low-frequency earth-

quakes beneath Iwate volcano, northeastern Japan,

, , .

Nakamichi, H., H. Watanabe and T. Ohminato, , Three-

dimensional velocity structures of Mount Fuji and the

B , doi : . / JB .

.

.

Onizawa, S., H. Mikada, H. Watanabe and S. Sakashita, ,

A method for simultaneous velocity and density inver-

sion and its application to exploration of subsurface

structure beneath Izu-Oshima volcano, Japan,

, .

.

.

Tanaka, S., H. Hamaguchi, T. Nishimura, T. Yamawaki, S.

Ueki, H. Nakamichi, T. Tsutsui, H. Miyamachi, N. Mat-

suwo, J. Oikawa, T. Ohminato, K. Miyaoka, S. Onizawa,

T. Mori and K. Aizawa, , Three-dimensional P-wave

velocity structure of Iwate volcano, Japan from active

seismic survey, ( ), doi : . /

GL .

Aizawa, K., R. Yoshimura and N. Oshiman, , Splitting of

the Philippine Sea Plate and a magma chamber beneath SP

Mt. Fuji, , L , doi : . / .

GL .

Huchon, P. and H. Kitazato, , Collision of the Izu block .

with central Japan during the quaternary and geologi-

cal evolution of the Ashigara area, , .

.

Iidaka, T. M. Mizoue, I. Nakamura, T. Tsukuda, K. Sakai, M. .

Kobayasi, T. Haneda and S. Hashimoto, , The upper a

boundary of the Philippine Sea plate beneath the west- .

ern Kanto region estimated from S-P-converted wave, b

Lees and

Ukawa,

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-

Ukawa, M., , Activity of Fuji volcano, Reports on vol- eastern Japan inferred from active seismic survey,

canic activities and volcanological studies in Japan for , .

the period from to , . Zhang, H. and C. H. Thurber, , Double-di erence tomo-

graphy : the method and its application to the Hayward

. fault, California, , .

Yamawaki, T., S. Tanaka, S. Ueki, H. Hamaguchi, H. Naka- Received April ,

michi, T. Nishimura and et al., , Three-dimensional Accepted August ,

J.Volcanol. Geotherm. Res.,

Bull. Seism. Soc. Amer.,

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