2-D resonances are known to occur in sedimentary basins, and it has been reported that the fundamental mode shapes appear to reflect the bedrock shape. This suggests that the bedrock shape of a valley can be estimated by evaluating the relationship between the mode shapes and the bedrock shape, and by identifying the resonance modes from the observation records of the ground motions. In the present study, the fundamental mode shapes of a small-scale valley were identified by applying the frequency domain decomposition (FDD) technique to microtremor observation records. 2-D finite difference models were used to investigate the relationship between the mode shapes and the bedrock shape. A new method was proposed for estimating the bedrock shape by comparing the mode shapes obtained from observation records and a numerical analysis. Furthermore, the applicability of the new method was confirmed using synthetic and observed data.

已知二维共振发生在沉积盆地中，据报道，基本模式形状似乎反映了基岩形状。这表明，可以通过评估振型与基岩形状之间的关系，并通过从地震动的观测记录中识别共振振型来估计山谷的基岩形状。在本研究中，通过将频域分解 (FDD) 技术应用于微震观测记录，确定了小尺度谷的基本振型。二维有限差分模型用于研究振型与基岩形状之间的关系。通过比较从观测记录和数值分析获得的振型，提出了一种估计基岩形状的新方法。此外，