Abstract
A later phase propagating horizontally southeast was detected to the south of Japan Railway line in the lowlands of Sumiyoshi, Kobe, by the tripartite installed at the Nada junior high and high school station of the Sumiyoshi Linear Seismic Observation Array, for aftershocks of the 1995 Hyogo-ken Nanbu earthquake. A frequency wave-number spectral analysis revealed a phase velocity of 300-400 m/s and energy concentration in the frequency range 2.0-4.0 Hz. According to the delay after S-wave arrival, its phase velocity and its propagating direction, it is believed this phase was a secondary wave converted from incident S-wave at the geological fault along the base of the Rokko mountain range.
