Many open cracks were found on the Yayoi-age dwelling site on the Kamo-terrace in Kawanishi City, Hyogo Prefecture. The vertical displacements at some large cracks found on the sectional layer are north up and the maximum displacement is estimated to be 40cm.
The north up inclination of the Kamo-terrace in the Quaternary period is consistent with the sense of the vertical displacement. It is confirmed that these open cracks were formed not by a land slide but by a large earthquake. However, there is no evidence of such an earthquake in the historical age.
Arima-Takatsuki tectonic line is located at 500m northward from the Kamo-terrace. It is known that the mountain region divided from the plain by this tectonic line was lifted in Quaternary period. The existence of the cracks on the Kamo-terrace suggests that this tectonic line was activated after the Yayoi-age (B. C. 3c. -A. D. 3c.).
