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首页> 外文期刊>Journal of Asian earth sciences >Geological records of South China Sea tsunamis on Penghu Islands, Taiwan
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Geological records of South China Sea tsunamis on Penghu Islands, Taiwan

机译：台湾澎湖群岛南海海啸的地质记录

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摘要

The coasts around the South China Sea are highly populated and threatened by the ubiquitous tsunamigenic structures of the Manila trench-arc system. However, owing to limited historical records and rare geological findings of tsunamis, our comprehension of and preparation for regional tsunami risks are far from sufficient. Located in the NE South China Sea, the Penghu Islands in Taiwan's western offshore area are selected for a geological tsunami survey because of their advantages of lengthy coastlines and abundant upper Holocene deposits.Three gravel layers of marine incursion events were identified and correlated between three far-separated coastal sections based on the constraints of radiocarbon dating. Intercalated with talus, soil, and dune sand, the gravel layers are poorly sorted, matrix-supported, up to boulder in size, and dominated by marine bioclastics and rounded basalts, which are identical to modern beach gravels. The deposits are located 3-4 m above present sea level, which is significantly higher than the local high tide levels and maximal typhoon surges of 2-3 m high. Furthermore, the deposits are distributed extensively on south-facing shores, indicating relatively large and abnormal inundation events from the South China Sea.Based on the radiocarbon dating results of the event deposits, three tsunamis likely occurred in the periods from the 4th to 6th, 11th to 12th, and 15th to 16th centuries. A recurrence interval of 400-500 years is accordingly associated with these event deposits. These findings demonstrate great tsunami risks exist in the South China Sea basin and call for more attestations and future studies. The major contribution of this study is also supported by the AD 1076 Guangzhou tsunami, which is comparable in age to the middle event deposit.
机译：南中国海周围的沿海人口稠密，受到马尼拉海沟弧系普遍存在的海啸致灾结构的威胁。但是，由于海啸的历史记录有限和罕见的地质发现，我们对区域海啸风险的理解和准备还远远不够。台湾西部的澎湖列岛位于中国南海东北部，因其海岸线长，上全新世沉积丰富而被选为地质海啸调查对象，确定了三个砾石层的海洋入侵事件并将其与三个远海事件相关联-根据放射性碳测年的约束将沿海地区分开。砾石层夹杂有距骨，土壤和沙丘沙，分类不善，基体支撑，大小不等，大到由巨石构成，并以海洋生物碎屑和圆形玄武岩为主，与现代海滩砾石相同。这些矿床位于当前海平面以上3-4 m，这明显高于当地的高潮水平和最大2-3 m的台风潮涌。此外，这些沉积物广泛分布在朝南的海岸上，表明南海有相对较大且异常的淹没事件。根据事件沉积物的放射性碳测年结果，在第四至第六时期可能发生了三个海啸， 11至12世纪以及15至16世纪。因此，这些事件沉积物的复发间隔为400-500年。这些发现表明，南海盆地存在巨大的海啸风险，因此需要更多的证明和未来的研究。这项研究的主要贡献也得到了公元1076年广州海啸的支持，其年龄可与中层事件矿床相提并论。

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