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ASsudy on the improvement of far-field tsunami waming system

远场海啸预警系统改进研究

基本信息

批准号：
14380205
负责人：
SHUTO Nobuo
金额：
$ 3.78万
依托单位：
Iwate Prefectural Uriversity
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

For the improvement of the accuracy of far-field tsunami warning system, we studied (1) Mechanism and characteristics of multiple reflection of tsunamis incident on a continental shelf, (2) An estimation method of tsunami source region by using the real-time observation data, (3) Characteristics of dispersion effect of tsunami during the propagation and run-up process.For the study (1), we derived an analytical solution of tsunamis which are obliquely incident on a offward-finite constant slope. The incident waveforms are assumed to be transient. Based on the solutions obtained, characteristics of transient tsunami propagations on the slope are discussed in terms of the several conditions of incidence such as horizontal incident wave scale, incident angle and incident waveform. When tsunamis are incident almost parallel to the shoreline, multiple reflected waves reveal and are trapped on the slope. The solution indicates that the interference between multiple reflected waves and incoming incident waves could be a contributing cause of conspicuous amplification of tsunamis on the slope.For the study (2), we developed an estimation method for tsunami source region by using the hypothetical offshore tsunami gauge. The method enables to estimate the fault parameters of W and L (Width and Length), which reflects the horizontal extent of tsunami source region, within 20 % of estimation errors.For the study (3), we developed a numerical model with Boussinesq-type equations, which enables to estimate the dispersion effect during the process of tsunami propagation and run-up. The model was validated through the case study of the 1983 Nihonkai-Chubu earthquake tsunami to obtain the better estimate of tsunami height to explain the observed tsunami height along the coast of Japan sea.

为了提高远场海啸预警系统的准确性，我们研究了（1）海啸在大陆架上的多次反射机制和特征;（2）利用实时观测资料估算海啸震源区的方法;（3）海啸在传播和上升过程中的弥散效应特征。本文导出了海啸斜入射于一个向外的有限常斜坡上的解析解。假设入射波形是瞬态的。基于所得解，从水平入射波尺度、入射角和入射波形等几种入射条件出发，讨论了斜坡上瞬时海啸的传播特征。当海啸几乎平行于海岸线入射时，多个反射波显露出来并被困在斜坡上。结果表明，多次反射波与入射波的相互干扰可能是导致海啸在斜坡上显著放大的原因之一。在研究（2）中，我们提出了一种利用假定的近海海啸观测仪估算海啸震源区的方法。该方法能够在20%的误差范围内估计出反映海啸震源区水平范围的断层参数W和L（宽度和长度）。对于研究（3），我们开发了一个基于Boussinesq型方程的数值模型，该模型能够估计海啸传播和上升过程中的弥散效应。以1983年日本海中部地震海啸为例，对模型进行了验证，得到了较好的海啸高度估计值，解释了日本海沿岸沿着观测到的海啸高度。