ABSTRACT
A natural rock block, which was visited by he famous Black Ship visited Japan in 1853, exists in Nakagusuku Village. This natural rock structure and its vicinity has been recently designated as a touristic spot and the authorities are concerned with its static and dynamic safety. The authors have been asked to investigate the stability of this natural monumental rock block. For this purpose, a physical model of this block with a similar density was prepared and its stability was investigated using a shaking table. The block become unstable when the base acceleration exceeds 350 gals. The authors also studied how to increase the dynamic resistance of the block against large earthquakes using an agent to bond the block to its base. The experimental results clearly indicated that the increase of the resistance was possible and the overall seismic resistance of the block increases. The outcomes of this experimental study has been described and their implications are presented and discussed.
