Occurrence Properties of Giant Freak Waves in Sea Area around Japan

Wave data on H1/3, Hmax, etc. observed in the sea area around Japan are analyzed to investigate the probability distribution of Hmax/H1/3 and the occurrence properties of giant freak waves with wave heights exceeding 2H1/3 and 10 m. The analyzed results show that the occurrence probability of the giant freak waves could be argued generally under the Rayleigh extreme distribution, although it varies from area to area. Four-ninths of the extreme waves having the largest maximum individual wave height (Hmax)max at each observation point are occupied by the giant freak waves and moreover, they occur in lower sea states rather than in the severest one.