Thursday, June 15, 2006

Where Will You Be When the Big One Hits?

Last Sunday, the Daily Yomiuri had an article based on a report developed by the Tokyo metropolitan government. They estimate that, in the event of a large earthquake during the day, 3.9 million people will be stranded in central Tokyo, too far from home to walk and with no trains or other transport running. That's out of 11.44 million people away from home during the average day in Tokyo. If you include three neighboring prefectures, the number stranded could rise to 6.5 million people. That's a lot of people looking for dinner, some water, a place to lay their head, a toilet, a phone to borrow, and maybe some warm, dry clothes -- not to mention medical assistance.

Among statistical tidbits, it mentions that Shinjuku Station handles four million passengers a day. I've heard various figures for different stations, including (if I recall) 900,000 for Tokyo Station, which sounds low. I think the numbers vary depending on whether you're talking about people starting or terminating journeys, changing trains, or just sitting on a train passing through. With fourteen main platforms in the JR part of the station alone, and several connecting private lines (Odakyu, Keio (no relation to my university), and three subway lines), each with an average of several hundred trains a day and as many as fifteen cars with several hundred people each -- well, you do the math. Wikipedia's Shinjuku Station article (in English) says the number is 3.22 million.

The article says that 167,197 people will initially be stranded in Shinjuku (someone needs to teach them the difference between accuracy and precision -- or do they have a list of names already?), of whom more than 90,000 will be stranded until trains resume, which could be days. Designated emergency gathering points include major parks, but if it's raining and cold, you're not going to convince people to stay there for long.

Number of people initially expected to be stranded:









Tokyo198,309
Shibuya182,858
Shinjuku167,197
Ikebukuro165,733
Shinagawa127,864
Machida125,512
Ueno89,894
Hachioji84,528


The percentage of people expected to be stranded until train service resumes varies:










Station10-20km from home20+km from hometotal
Tokyo31,282111,146142,428
Shibuya28,13275,463103,595
Shinjuku21,49369,10190,594
Shinagawa17,60271,52889,130
Ikebukuro22,10162,66384,764
Ueno11,52232,71244,234
Machida10,37617,92028,296
Hachioji6,59010,76817,358


The article also says that on the busiest streets, the density of people may peak at 11 people per square meter 3-4 hours after the quake. That compares to 10 people per square meter on a very crowded train. Seems unlikely to me, but the point that it's going to crowded when everyone comes out of their offices and tries to walk home at the same time is quite valid.

I have some doubts about the numbers, but bottom line: when I get back from ISCA, an earthquake kit for the office is high on my priority list. It's way overdue already.

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