Guidance for construction of three-dimensional underground structure model for evaluation of earthquake ground motions

In order to investigate the cause of the amplification in earthquake ground motions, JNES prepared 'three dimensional underground structure model' and using this model analyzed and evaluated the earthquake ground motions. Therefore it was elucidated that the discordance formation of ground and a sudden change in the propagation velocity of ground motion are main causes of the ground motion amplification. Then, JNES collected various physical surveys and examination results in 'Kashiwazaki Vertical Array seismic motion monitoring System' (KAVAS) and developed 'the preparation process of three dimensional underground structure model'. (M.H.)