南海潜在海啸灾害的模拟

Simulation of potential tsunami hazards in the South China Sea

结合南海海域的地形条件、地质构造、地震学特征以及历史地震记录,在回顾总结国内外学者研究的基础上,分析了南海可能引发地震海啸的震源区域,并讨论了在我国南海沿岸发生海啸灾害的潜在可能性。采用目前在国际上广泛使用的COMCOT海啸模式,对马尼拉海沟的潜在地震引发的海啸进行了数值模拟计算,计算中包含了由地震参数到海面初始变形的转换、海啸的深水传播过程以及海啸的浅水传播过程。采用三重嵌套网格,外层网格对应于大范围的深水区域,使用球坐标系下的线性控制方程;第二层网格对应中等范围的较浅水区域,使用球坐标系下的非线性控制方程;第三层网格对应小范围的浅水区域,使用直角坐标系下的非线性控制方程。由模拟计算得到的海啸传时分布、近岸海面升降强度、四个特定点上海面高度随时间变化等的结果表明,我国南海沿岸遭受海啸袭击的可能性是存在的,应进一步对南海海啸进行监测、预警和研究。COMCOT模式性能良好,可用于对南海潜在地震海啸的进一步模拟研究。

Based on comprehensive consideration of topography, geological structure, seismological features and historical records, the authors analyze the hazardous tsunamigenic zones in the South China Sea and discuss the possibility of potential tsunami hazards in the region. A tsunami induced by a hypothetical earthquake in the Manila Trench is simulated using a nested 3-layer grid system with high resolution. Each grid area in the grid system can be configured with its own type of coordinate system depending on its coverage, simulation parameters as well as the governing equations in terms of the characteristics at different stages of tsunami propagation. This flexible, nested grid setup allows for a balance between computational accuracy and efficiency. The simulation results, such as the calculated travel time map, maximum surface elevation and water height series at four virtual gauges, indicate that the tsunami hazards could happen on the coasts off South China. Further research is necessary to determine the need for a monitoring system of tsunami in the region.