2000年鳥取県西部地震時の震源断層近傍における基盤地震動の推定 : 1995年兵庫県南部地震との比較

概要

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Bedrock motions are evaluated using the strong ground motions recorded at the KiK-net stations near the seismic fault of the 2000 Tottori-ken Seibu earthquake (M_j7.3). Analyses of the recorded motions reveals that the soil nonlinearity of soft surface layers plays an important role in site amplification between the two vertical array points during the main shock. Soil properties are adjusted to fit to spectral ratios by using the Genetic Algorithm for both the small aftershocks and the main shock. Input motions are calculated using the estimated soil models. The peak velocities of the bedrock motions are small compared with those in the Kobe City during the 1995 Hyogo-ken Nanbu earthquake (M_j7.3). Strength demand spectra indicate that the destructive power of bedrock motions is also less than those in Kobe, which could be one of the reasons why the structural damage was smaller than expected from the recorded magnitude.
2001-12-30