Don't Worry About Earthquakes, You're Going To Drown

[Mulboyne]

This reassuring picture actually comes from the section on Arakawa River disaster prevention which might suggest a certain lack of confidence in current countermeasures.

Asahi: 'Once in a millennium' flooding could claim 15,000 lives in Kanto region, panel says
"Once in a millennium" flooding could kill more than 15,000 people in the Kanto region if torrential rain caused the Tonegawa and Arakawa rivers to burst their banks, according to an estimate released Monday. A special panel to the government's Central Disaster Management Council said up to 11,000 people could die if massive flooding occurred in areas along the Tonegawa river and that 4,500 might perish if floodwaters raged in areas along the Arakawa river as well. In March, the same panel studying steps to counter widespread flooding publicized an estimate based on torrential rains pounding areas along the Tonegawa, causing flooding at a magnitude seen only once in 200 years...more...

Arakawa River System Arakawa Estimated Flood-Inundation Map Here. Also, related FG Threads: The Sinking Of Osaka and Tokyo is the next New Orleans

[Captain Japan]

The new link to the Asahi story is here.

[Mulboyne]

Mainichi: Arakawa River flood could submerge 97 subway stations in Tokyo, study shows

Nearly 100 train stations in Tokyo could end up flooded if the Arakawa River burst its banks due to heavy rain, an expert panel of the government's Central Disaster Management Council has warned. With current waterproofing measures, officials said there was a danger of 97 stations on 17 lines becoming more or less submerged, and that subway hub Otemachi Station in central Tokyo could end up flooded roughly three hours after the river breaks its banks. The council is now working on evacuation and flood prevention measures following Friday's report.

A total of 137 stations on 22 lines including eight Tokyo Metro lines, four Toei Subway lines, the JR Keiyo Line and the Keisei Oshiage Line were included in the study. Officials used the scenario of a major flood with about 550 millimeters of rain falling over three days. Such floods occur about once every 200 years. If the river embankment broke in Tokyo's Kita-ku, then 66 stations, including Tokyo and Otemachi, would be flooded in a space of 12 hours. Three hours later, the total would rise to 89, including Ginza and Kasumigaseki stations. After three days, a total of 97 stations would be flooded. Eighty-one of the stations would be completely submerged, leaving 121 kilometers of train lines underwater. The other 16 stations would be mostly submerged.

It also emerged that subways would act as drainpipes, enabling the damage to spread quickly. If the dike broke in Adachi-ku, the depth of the water at Kitasenju Station would reach 5 meters, creating great water pressure, and water that flowed into the tunnels would quickly reach the center of Tokyo. Otemachi Station would be flooded in three hours and Tokyo Station in four. A Cabinet Office representative said the damage could be even worse when considering buildings next to underground shopping areas. "The study does not go as far as to assume flooding from the entrances of buildings linked to underground shopping centers next to stations, and there's a possibility that the extent of flooding could be greater," the representative said. "There are also fears that buildings could be crippled, and people might not be able to escape in time. Urgent measures such as stopping water flowing in from entrances are needed."