傾斜層内におけるSH波の全反射伝播

抄録

In order to investigate the earthquake response of thick sedimintary layer on the pre-Tertiary basement in the Tokyo metropolitan area, the National Research Center for Disaster Prevention has established a small-scale strong-motion observation array at the Fuchu area in the west of Tokyo. In this paper, we report an earthquake response of sedimentary layer for the shallow earthquakes whose epicenters are located in the west of the array. The response characteristics of sedimentary layer for SH waves may be summarized as follows:
(1) A SH pulse train produced by total reflections at the upper boundary of dipping basement, is observed during the earthquakes whose shallow origins are located in the west of the array. The pulse train is modulated by the sedimentary layer and becomes a predominant pseudo-Love wave which appears just after the direct SH pulse in the Fuchu area.
(2) Such pseudo-Love wave is explained even by using a simple dipping layer model and the plane wave approximation. The train of total reflected pulses is calculated by using the Hilbert transform repeatedly.