地震規模・震源位置が同じ2地震による同一地点の観測記録に基づく応答スペクトル振幅のばらつき

抄録

The variations of the ground motion response spectra are examined by comparing pairs of ground motion records observed at the same site from two earthquakes with the same magnitude and hypocenter location. In the analysis, it is assumed that the variations of the spectral amplitude is composed of the between-events variations and the within-event variations (also called the intra-event variations and the inter-event variations), and evaluate the standard deviations of each variation.
The evaluation result of the logarithmic standard deviation of the total variations (σ) is about 0.35-0.45. And, the standard deviation of the between-events variations (σ_B) is about 0.2, and the standard deviation of the within-event variations (σ_W) is about 0.3-0.4. The σ_W decreases with increasing the distance. This distance dependence can be caused by the effects of scattering of seismic waves in the path.