The wave observation data at ten stations along the Southern Pacific Coast of Japan were analyzed for the distribution of extreme significant wave heights for the purpose of establishing the parent distribution in this region. The wave observation at these stations has been conducted every two hours for the duration of 8 to 25 years. The peaks-over-threshold method was used to define the extreme wave heights, the number of which ranged from 151 to 409 per station with the total number of 2884.
The candidate distributions of the FT-II (four), FT-I, and Weibull (four) were subjected to rejection tests by the DOL and REC criteria proposed by Goda, and the distribution with the least case of rejection was assumed as the parent distribution. The necessity to deal with the mixed population was clearly demonstrated for this region, because storm waves by typhoons were much greater than those by other disturbances. The population of extreme waves by typhoons seems to have the FT-I distribution as the parent, but the limitation in the sample size prohibits to draw the definite conclusion.