Modeling the dynamic process of tsunami earthquake by liquid-solid coupling model  

作　　者：蔡永恩[1] 赵志栋[1] 

机构地区：[1]Department of Geophysics,Peking University

出　　处：《地震学报》2008年第6期594-604,共11页Acta Seismologica Sinica

基　　金：National Natural Science Foundation of China (40521002 and 40474013).

摘　　要：Tsunami induced by earthquake is an interaction problem between liquid and solid.Shallow-water wave equation is often used to modeling the tsunami,and the boundary or initial condition of the problem is determined by the displacement or velocity field from the earthquake under sea floor,usually no interaction between them is consid-ered in pure liquid model.In this study,the potential flow theory and the finite element method with the interaction between liquid and solid are employed to model the dynamic processes of the earthquake and tsunami.For model-ing the earthquake,firstly the initial stress field to generate the earthquake is set up,and then the occurrence of the earthquake is simulated by suddenly reducing the elastic material parameters inside the earthquake fault.It is dif-ferent from seismic dislocation theory in which the relative slip on the fault is specified in advance.The modeling results reveal that P,SP and the surface wave can be found at the sea surface besides the tsunami wave.The surface wave arrives at the distance of 600 km from the epicenter earlier than the tsunami 48 minutes,and its maximum amplitude is 0.55 m,which is 2 times as large as that of the sea floor.Tsunami warning information can be taken from the surface wave on the sea surface,which is much earlier than that obtained from the seismograph stations on land.The tsunami speed on the open sea with 3 km depth is 175.8 m/s,which is a little greater than that pre-dicted by long wave theory,(gh)1/2=171.5 m,and its wavelength and amplitude in average are 32 km and 2 m,respectively.After the tsunami propagates to the continental shelf,its speed and wavelength is reduced,but its amplitude become greater,especially,it can elevate up to 10 m and run 55 m forward in vertical and horizontal directions at sea shore,respectively.The maximum vertical accelerations at the epicenter on the sea surface and on the earthquake fault are 5.9 m/s2 and 16.5 m/s2,respectively,the later is 2.8 times the former,and therefore,sea water is a good shock aTsunami induced by earthquake is an interaction problem between liquid and solid. Shallow-water wave equation is often used to modeling the tsunami,and the boundary or initial condition of the problem is determined by the displacement or velocity field from the earthquake under seafloor, usually no interaction between them is considered in pure liquid model. In this study, potential flow theory and the finite element method with the interaction between liquid and solid are employed to model the dynamic processes of the earthquake and tsunami. For modeling the earthquake, firstly initial stress filed to generate the earthquake is set up, and then the occurrence of the earthquake is simulated by suddenly reducing the elastic material parameters inside earthquake fault. It is different from seismic dislocation theory in which the relative slip on the fault is specified in advance. The modeling results reveal that P, SP and the surface wave can be found on the sea surface besides the tsunami wave. The surface wave arrives at the distance of 600 km from the epicenter earlier than the tsunami 48 minutes, and its maximum amplitude is 0.55 m, which is 2 times as large as that of the fault. Tsunami warning information can be taken from the surface wave on the sea surface, which is much earlier than that obtained from the seismograph stations on land. The tsunami speed on the open sea with 3 km depth is 175.8 m/s, which is a little greater than that predicted by long wave theory, √gh=171.5 m, and its wavelength and amplitude in average are 32 km and 2 m, respectively. After tsunami propagates to continental shelf, its speed and wavelength is reduced, but its amplitude become greater, especially, it can up 10 m and run 53 m forward in vertical and horizontal directions at sea shore, respectively. The maximum accelerations at the epicenter on the sea surface and on the fault are 16.5 m/s^2 and 5.9 m/s^2 , respectively, the former is 2.8 times the later, therefore, sea water is a good shock absorber. The acceleration at the

关 键 词：有限元 流固耦合 地震海啸 数值模拟 

分 类 号：P315.31[天文地球—地震学]