Development of an early detection method for near field tsunamis

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An objective of this research is to develop an early detection method for near field tsunamis. For this purpose, the tsunami generation mechanism, the use of the Rayleigh waves and the sea surface disturbance preceding tsunamis has been investigated, with the results shown below.1. On the relationship among tsunamis, Rayleigh waves and sea surface disturbance.The dynamic tsunami simulation method that estimates both the dynamic ground displacement considering the fault rupturing and Navier-Stokes equation in fluid domain has recently been developed. Using the method, the relationship among tsunamis, Rayleigh waves and sea surface disturbance has been investigated for the early detection.2. On the characteristics of Rayleigh wave propagation.From the dynamic tsunami simulation, the amplitude of the Rayleigh waves and the sea surface disturbance has-been found to become larger in the front area of the fault than that in other area. Especially, the amplitude is remarkably larger in the direction of the fault rupture propagation. Using tidal records in 1993 Hokkaido Nansei-Oki tsunami and the strong motion records in 1999 Chi-Chi Taiwan earthquake, the amplitude and the direction of the propagation have been investigated to confirm the above-mentioned characteristics.3. On tsunami run-up simulation using the VOF and the Nesting technique.In the dynamic simulation, SOLA-SURF method was used in fluid domain simulation, where only vertical wall conditions are allowed because of the limitations of the method. Thus, to simulate the tsunami run-up, we have removed the limitations using of the VOF and the Nesting method.