1996 Volume 44 Issue 5 Pages 577-590
To estimate the amplification characteristics of ground motion in the heavily damaged belt zone in Kobe City during the 1995 Hyogo-ken Nanbu earthquake, three-dimensional wave propagation analyses of a two-dimensional, deep irregular underground structure model with vertical discontinuity were performed using the hyperelement method for incident planar waves expected from the wavefields due to the source mechanism. The observation records from Kobe University, a rock site, are used as control data. The ground motion at the surface of the Osaka group layers and at ground surface are calculated, The effects of the deep irregular underground structure and shallow surface layers on ground-motion amplification are discussed. The analytical results show that ground motions in the heavily damaged belt zone was amplified due to a focusing effect in the deep irregular underground structure as well as the shallow surface layers, and that the calculated maximum acceleration distributions coincide closely with the distribution of structural damage.
