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Holocene sea-level change,crustal movement, and coral reef development in the Ryukyu Islands based on C-14 calendar ages

基于C-14历法的全新世海平面变化、地壳运动与琉球群岛珊瑚礁发育

基本信息

批准号：
15300304
负责人：
KAWANA Toshio
金额：
$ 4.29万
依托单位：
University of the Ryukyus
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

Large islands in the Ryukyus, such as Okinawa and Ishigaki, whose formative period of coral reefs goes back to 6800-7000 cal BP, have been affected by hydro-isostasy and locally crustal movement, while a small island of Zamami and a large island of Iriomote with younger coral reefs in 4000-5000 cal BP are due to without hydro-isostasy or without locally crustal movement.Holocene coral reefs in Okinawa developed from about 8500 to 6300 cal BP to have formed the first stage of the coral reefs in the tectonically active areas of the southern coast, while after 6300 cal BP the second and the third ones appeared in the inactive areas of the central and northern coasts.Large tsunamis in the southern Ryukyus generated in 1771 (Meiwa Tsunami), and about 500, 1000, 2000, 2400 cal BP probably due submarine thrust and landslide off Ishigaki Island. It is suggested that the Holocene tilting from southeast to northwest in Ishigaki on land is due to submarine thrust movements off Ishigaki. The highest run-up height of the Meiwa Tsunami is assumed to attain about 30-30 m above sea level in Ishigaki Island. Concentration of the tsunami boulders to the northern coasts in Tarama and Kuro Islands with circular coasts is presumed due to diffraction of tsunami waves. Large waves in about 3400 cal BP attacked the eastern coasts of Amami and Okinawa. Reef blocks in the southern Okinawa were moved by large typhoon waves in 1832 and in 1951.

琉球境内的冲绳岛、石垣岛等大岛的珊瑚礁形成时期可追溯到6800-7000 cal BP，受到了水均衡作用和局部地壳运动的影响，而较小的Zamami岛和较大的Iriomote岛的珊瑚礁形成时期为4000-5000 cal BP，由于没有水均衡作用或局部地壳运动的影响。冲绳全新世珊瑚礁发育时间约为8500 ~ 6300 cal BP，在南海岸构造活动区形成了第一阶段的珊瑚礁，6300 cal BP之后，在中部和北部海岸构造活动区出现了第二和第三阶段的珊瑚礁。1771年在琉球南部发生的大海啸（明治海啸），大约在500、1000、2000、2400 cal BP，可能是由海底冲力和石垣岛的滑坡引起的。认为石垣全新世陆地上由东南向西北倾斜是由于海底冲断运动所致。据推测，明治海啸的最高上升高度将达到石垣岛海平面以上30-30米左右。海啸巨石集中在塔拉玛岛和库罗岛北部海岸的圆形海岸是由于海啸波的衍射。大约3400 cal BP的大浪袭击了奄美和冲绳的东部海岸。1832年和1951年，冲绳岛南部的岛礁块被较大的台风浪移动。