A parametric study of tsunami fission generation in a bay geometry based on numerical simulation
A parametric study of tsunami fission generation in a bay geometry based on numerical simulation
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DOI：
10.1080/05785634.2017.1418797
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发表时间：
2018-01
影响因子：
2.4
通讯作者：
Y. Yamanaka;Shinji Sato;T. Shimozono;Y. Tajima
中科院分区：
文献类型：
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作者：
Y. Yamanaka;Shinji Sato;T. Shimozono;Y. Tajima
摘要海啸裂变会在海啸锋面产生短波，这些短波可能会扩大淹没面积，增加对建筑物的水动力，放大对海岸社区的破坏。因此，重要的是要了解海啸裂变在多大程度上在可变条件下产生这种短波成分，以便制定更好的海啸减灾战略和规划。这项研究进行了数值实验，以描述海啸在海湾发生裂变的条件。实验表明，海湾变窄引起的近岸海啸高度的放大和海湾尺度的共振增强了海啸的裂变。在此基础上，从海啸性质、海湾几何效应和海湾共振三个方面提出了海啸裂变发生的参数图。开发的图表应用于受2011年东北海啸影响的仙台、良里、吉滨和东湾。拟议的示意图一致地解释了视频片段中观察到的仙台湾和龙里湾发生海啸裂变的原因。图表还表明，海啸的裂变可能发生在吉滨湾。基于一个非线性频散波模型，对横滨湾和东尼湾的海啸变形进行了高分辨率数值计算。这一结果支持了该图解在描述横滨湾海啸裂变产生过程中的有效性。
ABSTRACT Tsunami fission generates short waves at the front face of tsunami and these short waves may expand the inundation area, increase the hydrodynamic forces exerted on structures, and amplify the damage to coastal communities. It is therefore important to understand to what extent the tsunami fission generates such short wave components under variable conditions for development of better tsunami disaster mitigation strategies and plannings. This study carried out numerical experiments to describe under which conditions the tsunami fission occurs in a bay. The experiments indicated that the amplification of the nearshore tsunami height induced by the narrowing bay geometry and the bay-scale resonance enhance the tsunami fission. Based on the computations, a parametric diagram for the occurrence of tsunami fission was proposed in terms of the tsunami properties, the effect of bay geometry and the bay resonance. The developed diagram was applied to Sendai, Ryori, Yoshihama, and Toni Bays, which were affected by the 2011 Tohoku Tsunami. The proposed diagram consistently explained the occurrence of tsunami fission in Sendai Bay and in Ryori Bay as observed in the video footage. The diagram also suggested that the tsunami fission would have occurred in Yoshihama Bay. A high-resolution numerical computation was performed to simulate the tsunami deformation in the Yoshihama Bay and Toni Bay based on a nonlinear dispersive wave model. The result supported the validity of the diagram in describing the generation of tsunami fission in Yoshihama Bay.