首都圏で観測された堆積層-基盤系の地震応答  [in Japanese] The earthquake responses of a sediment-bedrock system observed in the metropolitan area, Japan  [in Japanese]

A sediment with a thickness of several kilometers covers the pre-Tertiary basement, i.e., seismic bedrock, in the Tokyo metropolitan area. The seismic waves during an earthquake, are amplified and modulated by such a sediment-bedrock system. These modulated seismic waves are of imortance to bring up many serious problems related to earthquake disaster. The National Research Center for Disaster Prevention has deployed some strong-motion observation arrays in the metropolitan area, in order to investigate the characteristics of seismic waves modulated. As observational results, we made sure two fundamental earthquake responses of the sediment-bedrock system. One is due to the multiple reflections of S-waves at the sediment-bedrock system. The sediment is treated as a horizontally layered structure and Q-value representing the attenuation characteristics in the sediment, is approximately 50f (f=0.1〜3 Hz). The other is due to a series of total reflections of S-waves at the upper boundary of dipping bedrock. The train of totally reflected SH pulses generates a pseudo-Love wave.