| Project/Area Number |
16310120
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Natural disaster science
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
SASATANI Tsutomu Hokkaido Univ., Faculty of Sci., Asso. Prof., 大学院理学研究院, 助教授 (10002148)
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| Co-Investigator(Kenkyū-buntansha) |
KAGAMI Hiroshi Hokkaido Univ., Grad.School of Eng., Prof., 大学院理学研究院, 教授 (70016476)
TAKAI Nobuo Hokkaido Univ., Grad.School of Eng., Asso.Prof., 大学院理学研究院, 助教授 (10281792)
OKADA Shigeyuki Nagoya Institute of Technology, Prof., 大学院社会工学専攻, 教授 (50125291)
ISHIKAWA Hiroyuki Civil Eng. Res. Inst., for Cold Region, Director, 寒地土木研究所・寒地基礎技術研究グループ, 室長 (70414167)
SATOH Takashi Civil Eng. Res. Inst., for Cold Region, Researcher, 寒地土木研究所・寒地基礎技術研究グループ, 研究員 (30414171)
田近 淳 北海道立地質研究所, 地域地質部, 表層地質科長
池田 憲二 北海道開発局, 小樽開発建設部, 次長
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| Project Period (FY) |
2004 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥10,400,000 (Direct Cost: ¥10,400,000)
Fiscal Year 2006: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2005: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 2004: ¥7,200,000 (Direct Cost: ¥7,200,000)
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| Keywords | 2003 Tokachi-oki Earthquake / Long-period seismic wave / Non-linear soil response / Velocity response / Source effect / Propagation path effect / Basin surface wave / attenuation relationship / 地下構造調査 / 最大地動速度 / 微動アレー観測 / 非線形地震応答 / 最大地動加速度 / 計測震度 / 速度応答スペクトル / S波震源スペクトル / 微動のアレー観測 |
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| Research Abstract |
The 2003 Tokachi-oki earthquake, a great interplate earthquake (Mw8.3), is the first M8 class earthquake in Japan since the dense strong-motion networks such as the K-NET and KiK-net have been deployed. We examine spatial distributions of velocity responses (damping factor h=0.05) with various natural periods for this earthquake by using the dense strong-motion network data. The short-period (T=0.1sec; T=natural period) velocity response distribution shows a typical feature for subduction-zone earthquakes; the high response values are observed along the Pacific coast of north Japan. This feature is explained by the S-wave attenuation structure beneath north Japan; that is, the path effect. On the other hand, the long-period (T=20sec) velocity response distribution shows a peculiar feature: at comparable distance, the response values in the northern part of the epicenter are higher than those in the south-western part. This peculiar feature is mainly explained by the source effect; the radiation pattern of long-period Rayleigh waves.
We find various types of the site effects. A remarkable one is excitation of long-period basin surface-waves at large plains with thick sedimentary layers. The other remarkable one is nonlinear site response. We find mild nonlinear site response at a soft soil site located on flood plain deposits; the nonlinearity is confirmed by comparing the transfer functions for weak and strong motions using the downhole array data. The distinctive nonlinearity is also observed at a not-so-soft soil site located on reclaimed land during the largest aftershock; the accelerogram shows a spiky waveform.
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