KATSUAKI KONN۰ - Department of Civil Engineering, Shibaura Institute of Technology, ۳-۹-۱۴, Shibaura, Minato-ku, Tokyo Japan
SHUNICHI KATAOKA - Institute of Technology, Shimizu Corporation ۳-۴-۱۷, Echujima; Koto-ku, Tokyo ۱۳۵-۸۵۳۰ Japan

The ground strain induced by Rayleigh wave may play a key role in designing a long structure, such as a pipeline. The strain is a function of ground velocity motion and phase velocity. However, it is difficult to calculate the phase velocity of Rayleigh wave without a high performance computer. Therefore, we propose a simple estimation method for a phase velocity of fundamental-mode Rayleigh wave in multi-layered media. This method uses only S-wave velocity and thickness of each layer and gives an approximate phase velocity at any period. Furthermore, this method can be applied to direct estimation for the S-wave velocity structure from observed phase velocities of Rayleigh wave.