Geomorphological study on large tsunamis in coral sea region.

本项目旨在阐明历史和史前大型金枪鱼的自然属性。本次研究选择了琉球群岛南部岛屿作为研究区域，主要在1771年遭受过海啸袭击的石垣岛和宫古岛进行了实地考察，通过对珊瑚化石的放射性碳年龄分析及其在陆地上的分布，可以恢复海啸发生的时间、地点和强度。海啸沉积物的放射性碳年龄显示，这些岛屿曾多次受到1771年规模或更大规模的图马尼群岛的袭击。根据海啸沉积物的年龄和分布，推测1771年以前的海啸发生在500年、11000年、1900年、2400年和4,000年左右。血压

This projext aims to clarify nateure of historical and prehistorical large tunamis. Southern islands of the Ryukyus are selected for the study area of this study, because tsunami deposits composed of subrecent reef coral fossils enable us to restore timing, location and magnitude of tsunamis by analyses of radiocarbon ages of the fossils and their distribution on land.Field study has been carried out mainly in the Ishigaki and Miyako Islands which have been attacked by destructive tsunami in 1771. Radiocarbon ages of tsunami deposits revealed that the islands have been repeatedly attacked by large tumanis of 1771 scale or bigger than that. It is deduced from the ages and distribution of tsunami deposits that tsunamis prior to 1771 took place about 500,1,1000,1,900,2,400 and 4,000 yr. B.P..