In 1999, Typhoon 9918 struck Kyushu Island, which is located in Western Japan. The maximum anomaly storm tide was estimated to be about 3 m along a coast. Due to the storm surge and wind waves the typhoon caused enormous damage to maritime structures. In this paper, the number of damage cases of maritime structures along the coastline caused by Typhoon 9918 is estimated by using the so-called Magnitude Method. The Magnitude Method is defined based on the maximum wind speed near the center and the size of the typhoon at a latitude of 30° N. The size of the typhoon is defined as the area for which the wind speed is greater than 15 m/s. The intensity of the typhoon is defined as the area in which the maximum wind speed occurred. The magnitude of a typhoon is defined by a combination of the rank of its intensity and its size. The number of damage cases is estimated as follows: The path of Typhoon 9918 is determined from the location and the moving direction of the typhoon at a latitude of 30° N. The vulnerability index of each coast is determined based on the path of the typhoon and coastline. The value of the so-called smoothed number of damage cases is calculated by using the index of vulnerability and the magnitude of Typhoon 9918 at a latitude of 30° N. The value of the damage cases along a coast is estimated by substituting the value of smoothed number of damage cases and the total number of damage cases by all 74 typhoons during past 25 years at the same coast. The Improved Magnitude Method can be used to estimate the number of damage cases of maritime structures that will occur along the coast before a typhoon strikes.
Hashimura, Ryusuke, "Using The Improved Magnitude Method To Forecast Damage Level Caused By Typhoon 9918" (2014). CUNY Academic Works.