aftershock observation for the noto hanto earth- quake · ˙ 2 ( ˙3 5 ˙6) 225 bull. earthq. res....

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Page 1: Aftershock Observation for the Noto Hanto Earth- quake · ˙ 2 ( ˙3 5 ˙6) 225 Bull. Earthq. Res. Inst. Univ. Tokyo Vol. pp. *e-mail: coco@eri.u-tokyo.ac.jp Earthquake Research Institute,

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225

Bull. Earthq. Res. Inst.

Univ. Tokyo

Vol. pp.

* e-mail : [email protected]

Earthquake Research Institute, University of Tokyo, Institute of Seismology and Volcanology,

Graduate School of Science, Hokkaido University, Graduate School of Science and Technology,

Hirosaki University, Research Center for Prediction of Earthquakes and Volcanic Eruptions,

Graduate School of Science, Tohoku University, Faculty of Science, Chiba University, Graduate

School of Natural Science and Technology, Kanazawa University, Research Center for Seismology,

Shinichi Sakai , Aitaro Kato , Eiji Kurashimo , Takashi Iidaka , Toshihiro Igarashi ,

Naoshi Hirata , Takaya Iwasaki , Toshihiko Kanazawa , Shigeru Watanabe , Toshio

Haneda , Masaru Kobayashi , Katsumi Miura , Reiko Miura , Kiyoko Tagami , Izumi

Ogino , Mamoru Saka , Atshi Watanabe , Koji Miyakawa , Kei Katsumata , Hiroaki

Takahashi , Minoru Kasahara , Ryo Honda , Takahiro Maeda , Masayoshi Ichiyanagi ,

Teruhiro Yamaguchi , Masahiro Kosuga , Tomomi Okada , Junichi Nakajima , Shu-

ichiro Hori , Takashi Nakayama , Kyohei Nii , Akira Hasegawa , Toshio Kono , Shuichi

Suzuki , Noriko Tsumura , Risa Kobayashi , Kenji Nozaki , Yoshihiro Hiramatsu ,

Katsunori Sugaya , Aiko Hayashi , Tetsuya Hirose , Akihiro Sawada , Keisuke Ta-

naka , Yoshiko Yamanaka , Haruhisa Nnakamichi , Takashi Okuda , Yoshihisa Iio ,

Kin’ya Nishigami , Masatoshi Miyazawa , Hiroo Wada , Norio Hirano , Setsuo Nakao ,

Hiroshi Katao , Shiro Ohmi , Kiyoshi Ito , Takuo Shibutani , Yasuyuki Kano , Issei

Doi , Shunta Noda , Takeshi Katagi , Yohei Nishitsuji , Satoshi Matsumoto , Ken

Matsushima , Atsushi Saiga , Hiroki Miyamachi , Kazutoshi Imanishi , Yasuto Kuwa-

hara , Ikuo Cho , Makoto Hoshino , Tetsuya Takeda , Yoichi Asano , Yohei Yuku-

take , Tomotake Ueno , Takuto Maeda , Takanori Matsuzawa , Syutaro Sekine ,

Makoto Matsubara and Kazushige Obara

Aftershock Observation for the Noto Hanto Earth-

quake

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Page 2: Aftershock Observation for the Noto Hanto Earth- quake · ˙ 2 ( ˙3 5 ˙6) 225 Bull. Earthq. Res. Inst. Univ. Tokyo Vol. pp. *e-mail: coco@eri.u-tokyo.ac.jp Earthquake Research Institute,

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226

Fig. . Seismicity in and around the Noto Peninsula in Central Japan. Distribu-

tion of the micro earthquakes was determined by JMA. Star indicates the epi-

center of the main shock of the Noto Hanto Earthquake.

Volcanology and Disaster Mitigation, Graduate School of Environmental Studies, Nagoya Univer-

sity, Disaster Prevention Research Institute, Kyoto University, Institute of Seismology and Vol-

canology, Faculty of Sciences, Kyushu University, Faculty of Science, Kagoshima University,

National Institute of Advanced Industrial Science and Technology, National Research Institute

for Earth Science and Disaster Prevention

The Noto Hanto Earthquake occurred on March , , in the Noto Peninsula, central

Japan. A half day after the main shock, we started installing temporary seismic stations in order to

determine the precise locations of its aftershocks. Ten universities and two research institutes

deployed temporary seismic stations in and around the source area. The observation lasted for

about two months. We relocated aftershocks with arrival time corrections at each station. The

relocated hypocenters show relatively small errors, less than . km in the horizontal direction and

less than . km depth. Most of the relocated hypocenters are about . km shallower than those

determined by JMA. The precise aftershock distribution extends into a shallower area than the

original, and it coincides with sea floor ward extension of the active faults previously known by a

sonic reflection survey.

: Noto Hanto Earthquake, aftershock observation, hypocenter distribution

GPS

M . cm cm

Fig.

,

cm km

Abstract

Key words

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Page 3: Aftershock Observation for the Noto Hanto Earth- quake · ˙ 2 ( ˙3 5 ˙6) 225 Bull. Earthq. Res. Inst. Univ. Tokyo Vol. pp. *e-mail: coco@eri.u-tokyo.ac.jp Earthquake Research Institute,

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Fig. . Location map of the stations by the group for the Noto

hanto Earthquake with the telemetered seismic stations.

M .

Yamada

km Obara

M .

km

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km

Fig.

et al.,

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Page 4: Aftershock Observation for the Noto Hanto Earth- quake · ˙ 2 ( ˙3 5 ˙6) 225 Bull. Earthq. Res. Inst. Univ. Tokyo Vol. pp. *e-mail: coco@eri.u-tokyo.ac.jp Earthquake Research Institute,

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Fig. . Spatial and temporal distribution of the seismic stations. Open triangles, the solid tri-

angles and the crosses indicate the stations that newly set up, the stations that have been set

up and the telemetered stations, respectively.

Fig.

-

-

Page 5: Aftershock Observation for the Noto Hanto Earth- quake · ˙ 2 ( ˙3 5 ˙6) 225 Bull. Earthq. Res. Inst. Univ. Tokyo Vol. pp. *e-mail: coco@eri.u-tokyo.ac.jp Earthquake Research Institute,

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Table . Summary of the operation period, recorder, sensor, sensitivity, natural frequency, and locations

of the temporary stations.

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Page 6: Aftershock Observation for the Noto Hanto Earth- quake · ˙ 2 ( ˙3 5 ˙6) 225 Bull. Earthq. Res. Inst. Univ. Tokyo Vol. pp. *e-mail: coco@eri.u-tokyo.ac.jp Earthquake Research Institute,

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Table . -wave velocity structure models

used for hypocenter determination.

is assumed to be . .

Fig. . Station corrections of and waves. Value of the station correction is color coded, blue corresponds to

the thin sediment and red corresponds to the thick sediment.

Hz . .

Hz Table

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P S Hypomh Hirata and Matsu’-

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Page 7: Aftershock Observation for the Noto Hanto Earth- quake · ˙ 2 ( ˙3 5 ˙6) 225 Bull. Earthq. Res. Inst. Univ. Tokyo Vol. pp. *e-mail: coco@eri.u-tokyo.ac.jp Earthquake Research Institute,

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Fig. . (a) Comparison between the hypocenters determined by JMA (end of line)

and those determined in this study (open circle). (b) NE-SW striking vertical

cross-section view of the hypocenters. The strike of the cross-section is de-

gree from north to east and perpendicular to the direction of the geological

structure in this region. (c) NW-SE striking vertical cross-section view of the

hypocenters. The epicenters determined by this temporary observation are lo-

cated approximate km shallower of those reported by the JMA routine

catalogue. (d) NE-SW striking vertical cross-section view of the hypocenters in

this study. (e) NW-SE striking vertical cross-section view of the hypocenters.

km

Yamanaka,

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Page 8: Aftershock Observation for the Noto Hanto Earth- quake · ˙ 2 ( ˙3 5 ˙6) 225 Bull. Earthq. Res. Inst. Univ. Tokyo Vol. pp. *e-mail: coco@eri.u-tokyo.ac.jp Earthquake Research Institute,

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Fig. . Spatial and temporal distribution of the aftershocks. Left is NE-SW striking vertical cross-section view.

Right is NW-SE striking vertical cross-section view. (a) (a ) Aftershocks for hours after the main shock were

represented. (b) (b ) Aftershocks from o’clock Mar. to o’clock Mar. were shown. (c) (c ) Aftershocks

from o’clock Mar. to o’clock were shown. (d) (d ) Aftershocks from Mar. to Apr. were shown. (e) (e )

Aftershocks from Apr. to May were shown.

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Page 9: Aftershock Observation for the Noto Hanto Earth- quake · ˙ 2 ( ˙3 5 ˙6) 225 Bull. Earthq. Res. Inst. Univ. Tokyo Vol. pp. *e-mail: coco@eri.u-tokyo.ac.jp Earthquake Research Institute,

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233

Obara, K., S. Hori, K. Kasahara, Y. Okada and S. Aoi, Hi-net :

Hirata, N. and M. Matsu’ura, Maximum-likelihood estima-

tion of hypocenter with origin time eliminated using

nonlinear inversion technique, ,

, .

.

Kato, A., S. Sakai, T. Iidaka, T. Iwasaki, E. Kurashimo, T.

Igarashi, N. Hirata, T. Kanazawa, and Group for the

aftershock observations of the Noto Hanto Earth-

quake, , Three-dimensional velocity structure in

the source region of the Noto Hanto Earthquake in

imaged by a dense seismic observation : Rift structure

related to the opening of the Japan Sea,

, .

Mikumo, T., H. Wada and M. Koizumi, , Seismotectonics

of the Hida region, central Honshu, Japan,

, .

National Research Institute for Earth Science and Disaster

Prevention (NIED), Earthquake mechanism informa-

tion, , http : //www.hinet.bosai.go.jp/topics/niigata

/.

High sensitivity seismograph network in Japan, ,

( ), Fall Meet. Suppl., Abstract S

A- .

Sakai, S., N. Hirata, A. Kato, E. Kurashimo, T. Iwasaki, and

T. Kanazawa, Multi-fault system of the Mid-

Niigata Prefecture Earthquake and its aftershocks,

, , .

Sakai, S., A. Kato, T. Iidaka, T. Iwasaki, E. Kurashimo, T.

Igarashi, N. Hirata, T. Kanazawa, and Group for the

aftershock observations of the Noto Hanto Earth-

quake, , Highly resolved distribution of aftershocks

of the Noto Hanto Earthquake by a dense seismic

observation, , .

Yamada, T., K. Mochizuki, M. Shinohara, T. Kanazawa, A.

Kuwano, K. Nakahigashi, R. Hino, K. Uehira, T. Yagi, N.

Takeda, and S. Hashimoto, , Aftershock observa-

tion of the Noto Hanto earthquake in using ocean

bottom seismometers, (in submit-

ted).

Yamanaka, Y., EIC Seismological Note, , http : //www.

eri.u-tokyo.ac.jp/sanchu/Seismo Note/ /EIC .

html, (in Japanese).

(Received January , )

(Accepted January , )

, ,

Sakai Kato

Sakai

. M .

P

M .

M .

. km

. km Kato

:

Phys. Earth Planet.Inter.,

Earth PlanetsSpace,

Tectonophys-ics,

Eos Trans. AGU,

Earth Planets Space,

Earth Planets Space,

Earth Planets Space

et al., et al.,

et al.

et

al.

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