| 講演要旨(和文) | | 近年，幾つかの原子力発電所の地盤において，予測より顕著に大きな地震動や局所的かつ特異な地震増幅特性が観測された．これらの現象は，地盤構造の不整形性による地震波の一種の焦点効果の影響と考えられる．高密度連続地震観測は，こうした地盤の不整形性の影響を検討するうえで有効な手法である．今回，我々は，東北電力の東通発電所の敷地内で，測点間隔が150〜200m程度の高密度地震観測を実施した．得られた観測データに基づき，サイトにおける地震増幅特性を検討した結果，スペクトル比および最大振幅比ともに方位依存性は認められず，当該サイトの地盤には，特異な増幅特性を生起させるような顕著な不整形性は存在しないことが明らかとなった． |
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| | 講演要旨(英文) | | In recent years, on the site of some nuclear power plants, the notably bigger earthquake motion and the local earthquake amplifying characteristic were observed. These phenomena are considered to be influences of a kind of focusing effect of the seismic waves by the irregularity in ground structure. High-density seismic observation is an effective technique in examination of the influence by such irregularity in the ground. This time, we carried out high-density seismic observation whose station interval is about 150-200m in the site of the Higashidoori plant of Tohoku-EPCO. As a result of examination of the earthquake amplifying characteristic in a site based on the observational data, it was shown clearly that remarkable irregularity to which azimuthal dependence does not exist in the site concerned. |
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