SEQUENCE OF SEDIMENTATION PROCESSES CAUSED BY THE 1992-FLORES-TSUNAMI- EVIDENCE FROM BABI-ISLAND

Sedimentation processes caused by a modern tsunami have been discussed from the point of view of geologic and numerical investigations of th e 1992 Flores tsunami in Indonesia. Geologic evidence on Babi Island s hows an invasion of two waves of different direction and magnitude, wh ich resulted in widespread deposition of marine sand on the north and south-southwest shores. On the latter, coarse and well-sorted carbonat e sand containing molluscan shells suggests that much more destructive waves swept across the southern coast, as compared with the northern coast, where the deposit included medium carbonate sand with a silty c omponent. A physical explanation for such destructive waves on the sou thern coast of Babi is provided by a numerical simulation of the tsuna mi generation and propagation. The geologic and numerical results indi cate that an isolated island surrounded by a circular shoreline or ree f edge will be subject to the most destructive waves on the coast on t he hack side of the island relative to the tsunami source.