都市における地震時出火・拡大延焼に関する被害予測

Abstract

An investigation of outbreak and spreading fires caused by an earthquake is considered much of protecting our city from earthquake damage. This paper deals with not only the outbreak fire estimated by making use of totally destroyed wooden houses and dangerous articles, but also the spreading fire based on the available factors inferred from big fires relating to spreading fire in the past. Especially, the effect of fire water supply is taken into consideration for the estimation of spreading fires at the standerd 500 m×500 m mesh in Nagoya city. The estimated results are summarized as follows ; (1) A number of outbreak fires is estimated in the area of the Nishi-ku, Nakagawa-ku and Nakamura-ku in the northern and north-western part of Nagoya city. (2) The area of spreaded fire damage is estimated at about four per cent of the 500 m^2 mesh area, under the conditions of 60 minutes after the outbreak fire and the wind velocity of 3. 7 m/s which is the mean valus. (3) The spreading fire damage in the case of the assumed Nobi earthquake, under the conditions of 60 minutes after outbreak fires and the wind velocity of 3.7 m/s and 10.0 m/s, is estimated at 10.9 and 20.1 per cent of the subject area of the present investigation, respectively. (4) In considering the damaged premise from the results of this paper, it is closely related with both the wind velocity and the general wooden houses percentage of the total wooden houses including fireretardant wooden houses. The damage seems to increase much more repidly with values over 65 par cent of the general wooden houses percentage.