Quantitative Analysis of Tsunami Disasters by The Jogan Earthquake

通过与海啸存款的粒度组成和相类比，估算了869年日本地震海啸的沉积物搬运方式。此外，海啸引发的水流的初始水力条件进行了沉积学评估，以增加对海啸助跑行为的认识。根据激光衍射粒度分析仪的粒度分析，明确了构成Jogan海啸存款的砂层向陆地的细化。这与我们对海啸泥沙输移和沉积的水力学实验结果一致。结果表明，沉积层的细化方式可以作为反映海啸能量耗散的重要判据。这些判据可为海岸地貌形成的理论认识提供自然地理条件.此外，他们可能会给我们的城市和工业基础设施的沿海地区的发展不可或缺的知识。2004年印度洋海啸后的有孔虫组合的变化清楚地表明了从泰国西南海岸的沉积物样品的微体古生物学分析。这意味着海啸反冲引起的浊流痕迹可以保存在海底沉积环境中。因此，海啸发生的历史是可能的基础上挖掘的海洋沉积物。2007年7月，在意大利佩鲁贾举行的国际大地测量学联合会第二十四届大会上，这些结果作为海啸灾害和沉积作用的一个实际例子得到了科学界的关注。

Mode of sediment transport by the 869 Jogan earthquake tsunami was estimated by analogy with grain-size composition and facies of the tsunami deposit. In addition, initial hydraulic condition of tsunami-induced currents was sedimentologically evaluated to increase knowledge on behavior of tsunami run-ups. Landward fining of the sand layer that comprises the Jogan tsunami deposit was clearly identified on the basis of the grain-size analysis by the laser-diffraction gram-size analyzer. This is consistent with the results from our hydraulic experiments of sediment transport and deposition of tsunamis. It is clarified that mode of fining of sedimentary layer can be treated as important criteria that reflect the energy dissipation of tsunami run-ups. These criteria may provide physical- geographic condition for theoretical understandings of formation of coastal topography. In addition, they may give us indispensable knowledge on developments of urban and industrial infrastructures of coastal areas.Changes in foraminiferal assemblages after the 2004 Indian Ocean tsunami were clearly demonstrated by the micropaleontological analysis of sediment samples collected from the southwest coast of Thailand. This implies that traces of turbidity currents induced by tsunami backwashes can be preserved in submarine sedimentary environments. Therefore history of tsunami occurrence is possible to uncover based on sediment excavation on the ocean. These results were presented and gained scientific attention in the XXIV General Assembly of IUGG that was held in Perugia, Italy, in July 2007, as an actual example of tsunami disaster and sedimentation.