2006 Fiscal Year Final Research Report Summary
A Study on Characteristics of Strong Ground Motions from the 2003 Tokachi-oki Earthquake
| 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)
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| Project Period (FY) |
2004 – 2006
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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 |
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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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Research Products
(12 results)
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[Journal Article] Source, path and site effects on strong ground motions from the 2003 Tokachi-oki earthquake sequence2007
Author(s)
Sasatani, T., Maeda, T., Takai, N., Miwada, G., Shimizu, G., Yamamoto, A., Noguchi, S.
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Journal Title
Proc.of 4^<th> Inter. Conference on Earthquake Geotechnical Engineering, June 25-28, 2007, Thessaloniki-Greece (in press)
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] Nonlinear site response in Urakawa area during the 2003 Tokachi-oki earthquake sequence2006
Author(s)
Miwada, G., Takai, N., Shimizu, G., Maeda, T., Sasatani, T.
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Journal Title
The 12th Japan Earthquake Engineering Symposium, Nov.3〜5, Tokyo No. 0095(CD-ROM)
Description
「研究成果報告書概要(欧文)」より
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