| 講演要旨(和文) | | 常時微動トモグラフィの浅部調査への適用性を評価するために現場実験を実施した．観測は，平常時の微動に加え，地震計アレイ周辺を人間が走って発生させた振動もあわせて，2.5m間隔に設置した49台の独立型の地震探査装置で収録した．周波数範囲5〜30Hzで分散曲線が得られ，非線形最小二乗法による逆解析を行って，CMP毎に1次元のS波速度モデルを求めた．さらに空間補間によって3次元のS波速度モデルを作成した．得られた速度モデルは，調査地点の既往の地質構造とも整合していた．調査にかかった時間は，地震計の設置と撤収も含めて3時間であり，複数測線で表面波探査を行う方法と比べると，非常に効率的な3次元探査であるといえる． |
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| | 講演要旨(英文) | | A field experiment of 3D ambient noise tomography with a dense array has been conducted to evaluate the applicability of the method for near surface investigations. We observed ground motion caused by running around the receiver array as well as ambient noise at steady state by forty-nine cable-less seismographs deployed by 2.5 m intervals. Dispersion curves for the frequency range between 5 and 30 Hz were obtained by CMP-SPAC method. 1D S-wave velocity models were estimated by an inversion based on non-linear least square method at each CMP, and we converted them to a 3D model by a spatial interpolation. The obtained S-wave velocity model agrees with existing geological information at the site. The time required for the survey was only 3 hours including a deployment and removal of the receivers |
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