Simple estimation method of response characteristics in surface layer based on microtremor H/V spectral ratios

从工程角度出发，提出了一种利用地脉动H/V谱比估算地表层地震反应特征的简便方法，并利用地震观测资料验证了该方法的适用性.对实测的地脉动H/V值进行了详细的分析，并与地面观测的地脉动H/V值及地面与地面之间的传递函数进行了比较。从而证实了地脉动H/V近似于表层水平和垂直响应特征的比值.对于地表地震反应特性的简单估计方法，根据各种检验结果，我们判断采用脉动峰值频率及其幅值H/V的方法是比较合适的.为了验证简单估计方法的适用性，将基于KiK-net的钻孔数据的理论地震响应与简单方法获得的估计结果进行了比较，并且，2004年近海纪伊半岛地震时，基于东野强震观测网和野比谷强震观测点观测记录的响应特征比较，进行了简单的估计结果。结果表明，地面上最大加速度幅值的比值平均约为1.0，标准差约为0.4。因此，考虑到1.4倍的估计结果，从安全的角度可以预测从薄到厚层的地面的地震反应，可以说，所提出的方法是有用的，估计地震反应特性的初步阶段。

From the engineering viewpoint, we proposed a simple estimation method of seismic response characteristics of surface layer using the microtremor H/V spectral ratios, and verified its applicability based on the earthquake observation data.1. We performed the analysis of observed microtremor H/V data in detail, and compared this with the earthquake H/V observed at ground surface and the transfer functions between surface and bottom. Consequently, it was confirmed that microtremor H/V approximates to the ratio of horizontal and vertical response characteristics in surface layer.2. As for a simple estimation method of seismic response characteristics in surface layer, we judged that the method using the peak frequency and its amplitude of microtremor H/V was the appropriate, according to the result of various examinations.3. To verify the applicability of a simple estimation method, the theoretical seismic responses based on the borehole data of KiK-net were compared with the estimation results obtained from a simple method, and also, the comparison between the response characteristics based on the observation records at Tono strong motion observation network and the strong motion observation sites in Nobi valley during the 2004 Off Kii Peninsula Earthquake and the simple estimation results were carried out. As a result, the ratios of maximum acceleration amplitude on ground surface were roughly 1.0 in the average and the standard deviations were about 0.4. Therefore, the seismic responses of the ground with from thin to thick layer are predictable in safety side by considering 1.4 times estimation result, and it can be said that the proposed method is useful for estimating the seismic response characteristics in a preliminary stage.