[H-DS10] Tsunami and tsunami forecast

[HDS10-05] Three-dimensional large-scale numerical simulation of tsunami-generated infrasound and its application: Feasibility of early detection of tsunami

*Kan Okubo¹, Yoshiki Saito¹, Kentaro Uehara², Hidee Tatehata², Kenji hayashi², HASHIZUME MASAHIRO³ (1.Faculty of system design, TOKYO METROPOLITAN UNIVERSITY, 2.Japan Weather Association, 3.Chubu Electric Power Company)

Keywords:infrasound, atmospheric pressure wave, tsunami, large-scale numerical simulation, tsunami source estimation , tsunami source inversion

For several decades, pressure changes associated with tsunami generation have been observed in the case of huge earthquakes, and this phenomenon has been subject to various research efforts. Past studies have reported that a change in atmospheric pressure (low-frequency sound; infrasound) is induced by the generation of a tsunami. In 2011, our study group successfully observed the infrasound induced by the tsunami from the Earthquake off the Pacific Coast of Tohoku. Since infrasound propagates in the atmosphere at a speed faster than that of a tsunami, it is expected to be applicable to early detection of tsunami occurrence. In other words, using infrasound as one of the observation targets for tsunami detection would make it possible to further improve the robustness and stability of tsunami detection. However, for this phenomenon, there is insufficient detailed numerical analysis considering the effects of wave sources and atmospheric environment based on actual physical phenomena. According to the frequency of tsunami occurrence, it is important to establish a highly reproducible numerical analysis method for the propagation of tsunami-generated infrasound.Therefore, in this research, we implemented a three-dimensional large-scale propagation numerical simulation considering the wave source and atmospheric model NRLMSISE-00, which has been the international standard, and developed a method to numerically reproduce the propagation phenomenon of infrasound caused by the tsunami. Furthermore, we propose a method to reproduce the infrasound wave-form from the unit source using the developed numerical analysis model and to estimate the tsunami source inversion using the infrasound wave-forms. The source of low-frequency sound have high identity with the source of tsunami. We strongly believe that the tsunami source estimation using low-frequency sound waves is promising as a new early tsunami detection method.