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ELUCIDATION OF SEDIMENT TRANSPORT AND ENVIRONMENTAL MODIFICATION BY TSUBNAMIS

解释海啸的沉积物迁移和环境改变

基本信息

批准号：
10480091
负责人：
MINOURA Koji
金额：
$ 7.87万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

The fore-arc region of northeast Japan is a terrane of extensive seismic activity and tsunami generation, and the coastal areas facing the Pacific Ocean have been repeatedly attacked by tsunamis. On July 13,869 a tsunami triggered by a large-scale earthquake invaded the coastal zones, causing extensive deposition of well-sorted fine sand over the plains. Sedimentological analysis and hydrodynamic modeling indicate that the sand layer was developed by the first wave of the tsunami, and we conclude that low-lying coastal zones are susceptible to extensive flooding during tsunami runup. Traces of large-scale invasion by older tsunamis are recorded in the coastal sequences at regular chronological intervals, and we indicate that the coastal plains of northeast Japan are in danger of tsunami disasters in the near future.The Pacific coast of NE Japan is notorious for the repeated invasion of tsunamis. The Sendai plain, however, has not been affected by a large tsunami since the occurrence of … More the Jogan event. Rapid urbanization has advanced to the coastal areas. It must be recognized that understanding of the timing and scale of potential tsunami occurrence is an urgent requirement, if tsunami mitigation efforts on the densely populated coast are to be successful. The elucidation of the cause and effect of regionally extensive invasion of the Jogan tsunami is indispensable not only to prevent a disaster but also to gain an understanding of tectonic processes of the fore arc. In this study, the Jogan tsunami deposits were studied using sedimentological analyses and hydrodynamic models in an attempt to make clear the mechanism of wave penetration more than 4 km beyond the coastline.More than 100 years have passed since the beginning of scientific observation in NE Japan, and inundation distance of tsunamis exceeding 2 km beyond the shore was never observed during this time interval . It is inferred from the historical documents that seawater inundation by the Jogan tsunami reached 4 km or more inland from the coast. The deep penetration of seawater mean an occurrence of unprecedented large-scale tsunami. Less

日本东北部的弧前地区是广泛的地震活动和海啸发生的地体，面向太平洋的沿海地区多次受到海啸的袭击。869年7月13日，一场由大规模地震引发的海啸侵袭了沿海地区，在平原上造成了大量分选良好的细沙沉积。沉积学分析和水动力模拟表明，沙层是在海啸第一波的作用下形成的，我们得出结论，在海啸抬头期间，低洼海岸地带容易受到大范围洪水的影响。有规律的时间间隔在海岸序列中记录了较老海啸大规模入侵的痕迹，我们表明日本东北部沿海平原在不久的将来面临海啸灾害的危险。日本东北部的太平洋海岸以多次海啸入侵而臭名昭著。然而，自…发生以来，仙台平原一直没有受到大海啸的影响更多的是乔根事件。快速城镇化向沿海地区推进。必须认识到，如果要在人口稠密的沿海地区成功减缓海啸，迫切需要了解潜在海啸发生的时间和规模。阐明Jogan海啸区域性大范围入侵的原因和后果，不仅对于防止灾难，而且对于了解前弧的构造过程，都是必不可少的。本研究利用沉积学分析和水动力模型对Jogan海啸沉积物进行了研究，试图弄清海岸线以外4公里以上海浪的穿透机制。自日本东北部开始科学观测以来，已经过去了100多年，在这段时间内从未观察到超过2公里以外的海啸淹没距离。从历史文献中推断，乔根海啸造成的海水淹没距离海岸内陆4公里或更远。海水的深度渗透意味着史无前例的大规模海啸的发生。较少