| 講演要旨(和文) | | 石巻市桃生町は東北地方太平洋沖地震（M9.0）の際，中心部で局所的に大きな被害を受けた．その原因として小田・戸田（2011）では卓越振動数の分布と家屋被害の関係から研究がなされており，卓越振動数が2.5Hz以上の地点と被害の大きい箇所が良く一致すること，かつ被害が大きい箇所では複数のピークや2〜4Hz付近まで卓越振動数に幅を持つものが多いことがわかった．しかし先行研究の時点では当地域における詳細な地下構造と家屋被害の関係までは把握できていない．本研究では微動アレイ観測を用いて詳細な地下構造を把握し，家屋被害の原因を地下構造から明らかにすることを目的とする．観測の結果，桃生町中心部に深度7.50〜10.00m付近からS波速度250m/s程度の構造が見られた．これは桃生町中心部に不整形な基盤構造があることを示し，これが揺れを増幅したため家屋被害に影響を与えた可能性が示唆される． |
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| | 講演要旨(英文) | | Monou-cho, Japan locally experienced significant damage during the 2011 Tohoku earthquake (M9.0). According to Oda and Toda (2011), there is a correlation between points of predominant frequency above 2.5 Hz and area of significant damage. Additionally, they revealed that predominant frequencies of area received significant destruction have multiplex peaks or broad range from 2 Hz to 4 Hz. While the previous research established the distribution of predominant frequencies in this area, it did not reveal the relationship between intricate underground structures and house damage. In this study, we aim to grasp the detailed underground structure by using microtremor miniature array method and reveal the cause of house damage from the underground structure. As a result of observation, S-wave velocity structure of roughly 250 m/s was found from 7.50m to 10.00 m below the center of Monou-cho. Such a feature may represent an anomaly in the basement rock under Monou-cho. The presence of this irregularity may have resulted in the amplification of S-waves, potentially affecting the amount of structural damage in the area. |
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