地震海啸上岸过程的数值模拟研究

For mega-earthquakes, the possibility of tsunami-associated earthquakes is much higher than that people estimated from experience. There are potential tsunami hazards that should not be neglected along the coastal areas of China. The inundation process of tsunami is a decisive factor in the disasters near shore. For the purpose of precaution and preparedness against natural calamities, a thorough study by numerical simulation of inundation process of tsunami and disaster evolution is significant to economic development and future planning in coastal areas. This study will start with the basic equations of fluid dynamics with the consideration of initial disturbance and shore features. First, the rupture process of the epicenter and the interaction between water and seabed will be considered in the simulation of the triggering mechanism of the tsunami, in order to build a more precise initial waveform model. Second, from the simulation of the moving boundary, we will propose a numerical model for the inundation of tsunami, which can be used to compute the run-up and simulate the formation process of the flood areas. Furthermore, the evolution, scale and governing factors of disasters will be investigated in detail. The effects of local topography and wave height will be taken into consideration. Finally, the model will be applied to evaluate the distribution of flood areas on Southern and Eastern China coast in the cases of earthquakes with different magnitude or type occurred in Manila and Ryukyu Trenches. The databases of hazard maps obtained from the refined grid model of real topography would play an important role in the urban planning, disaster prevention and reduction.

特大地震激发海啸的概率远高于人们的传统估计，我国沿海存在不容忽视的潜在海啸灾害。海啸的上岸过程是确定近岸成灾状况的关键，从防患于未然的角度出发，通过数值模拟的方法对海啸的上岸过程及其成灾机制进行深入的研究，对沿海经济发展和工程建设具有重要意义。在已有工作的基础上，我们将从流体动力学基本方程出发，通过考虑震源破裂过程和水岩相互耦合作用，建立和完善海啸的激发过程模型，用于获得更为精确的初始波形；基于对可移动边界的水波运动模拟，建立海啸上岸过程的数值模型，用于模拟上岸过程中的爬高和淹没区的形成过程；探讨近岸成灾状况的形式、范围、控制影响因素等问题。最后将数值模型应用于考察马尼拉海沟和琉球海沟等潜在的不同震级和类型的地震引发的海啸在我国东南沿海及台湾地区的局部地形条件下淹没区的分布，建立潜在灾害分布数据库，为城市建设规划、防灾减灾等提供依据。