Periodicity in fluctuations of typhoon disasters is investigated based on the results of spectral estimation. A model is developed for estimating global risk potential from the data of disasters where each number and its location are unknown, and risk against the loss of human lives caused by strong winds is assessed. The 9 year period in fluctuations of typhoon disasters is nearly resonant with the 9-11 year periods in the meteorological extreme-value series due to typhoons, such as the maximum wind speed, but has reduced to the 5.4-7.7 year periods in past 30 years. In addition, according to the risk assessment the values of the minimum critical wind speed, where disasters begin to occur, are small and the values of risk potential are large. Judging from the scale of typhoon and the present state of coastal and social environments, the potential of disaster prevention is still low in spite of the recent improvement in basic facilities. These facts indicate that the loss of human lives is chiefly produced in consequence of careless action to typhoons. Therefore, the occurrence of disasters strongly reflects human psychology related to typhoons, which should be taken into account in planning any disaster preventive works.

Key words: Typhoon disaster, Disaster spectrum, Extreame-value, Periodicity, Risk assessment, Risk potential, Human psychology.

*Department of Civil Engineering and Architecture, Faculty of Engineering, University of the Ryukyu