INUNDATION SIMULATION OF SUBWAY IN OSAKA CITY CAUSED BY NANKAI TROUGH MEGA EARTHQUAKE TSUNAMI FLOOD

Abstract

 The Cabinet Office of Japan issued that the Nankai Trough Earthquake will occur in the next 30 years with a high probability of occurrence. In urban areas, people use subways and underground spaces. These tend to be flooded by the tsunami. Therefore, people have to evacuate from the subway stations after the tsunami warning will be issued. The study area is Osaka City, which has many subways and underground mall. InfoworksICM (sewer/river integrted simulation software) was used to calculate the flood depth and the start time of the flooding subway stations. From the results, over 80% of all subway stations are flooded. All stations in study area were classified into stations directly inundated from the ground, stations indirectly inundated through subway tracks from other stations and non-inundated stations. It was revealed that the number of subway stations indirectly inundated through subway tracks from other stations was more than that of stations directly inundated from the ground. In addition, since water overflowed from the entrance of the subway stations and the tunnel gates, it is necessary to take measures to prevent secondary damage.