开阔海域越洋海啸波高计算的一种简化方法

A simplified method for calculation of wave height of trans-ocean tsunami in open ocean

该文研究了开阔海域中越洋海啸波高的简化计算方法。基于选取具有一系列断裂带长宽比的震源参数,采用Okada弹性变形理论生成初始海底变形,运用基于有限体积法的非线性浅水方程数值模型,模拟地震激发海啸在4 000 m水深的平底地形上的传播过程。通过监测布置在相对震源中心不同距离及方位角上测点的波面时间序列,研究海啸波高在不同距离及方位角上的分布规律,给出不同断裂带长宽比下越洋海啸传播过程中首波幅值的分布关系式;进一步分析了断裂带长宽比对模型参数的影响,得出了归一化的越洋海啸波高计算经验公式,并与日本2011年海啸实际记录进行对比,验证了该近似方法的有效性。

Abstr A simplified calculation model of wave height ot trans-ocean tsunami in open ocean Is presentea m me paper. A series of earthquake parameters with different fault length-width ratios are selected. The Okada model is used to generate seafloor deformation and the resultant initial wave field condition for the earthquake-triggered tsunami. The nonlinear shallow water equations based numerical model is used to simulate the propagation of earthquake-triggered tsunami on fiat seafloor of depth of 4000 m. The time series of surface elevation in monitor points located in different distances and azimuths from the epicenter are analyzed. The first wave crests are taken to analysis the distribution of first wave amplitude in different distances and azimuths. A series of formulas of tsunami wave height are then proposed for the cases of different epicenter length-width ratios by fitting formula coefficients according to the numerical results. At last, the accuracy of the proposed formula is verified by comparing with the DART records of the 2011 Japan Tohoku tsunami