Wednesday, August 03, 2005

Living in the shadow of death

(Hey, I spend most of my life trying to think rationally - surely I'm allowed a bit of melodrama in a blog title.)

Japan is one of the most seismically active places in the world, reckoned to suffer about 1000 earthquakes a year (and 20% of all the world's big ones). Regularly, there is one big enough to cause damage and injury - since we arrived in 2001, there have been big quakes in Hokkaido (8.3 magnitude) and Niigata (6.9). The former occurred some way from population centres, and there were no direct fatalities, but the latter killed about 50 people, injured 5,000 and over 100,000 had to be evacuated from ther homes. Just a few years previously, the Great Hanshin Earthquake killed about 6,400 and caused 10 trillion Yen of damage (100 billion US$), the costliest natural disaster in history. There are numerous smaller quakes which cause small amounts of damage and limited injury - falling furniture and broken windows and the like.

Of course, what everyone round here is waiting for is the next really big one - the overdue Kanto (Eastern region) Earthquake. The recent 6.0 magnitude Tokyo quake provided a reminder to all of us, without doing any real damage (I was up in a mountain hut and missed the excitement). The last big one, in 1923, killed about 140,000, mostly through firestorms racing through the streets of close-packed wooden houses. It's anticipated that a magnitude 7 shock (which seem to turn up every 70 years or so - you do the maths) could kill about 10,000, many in fires in some vulnerable older wooden housing in Tokyo. In a city of 30 million, that's not really such a huge proportion. For us foreigners, vigilante death squads are likely to be a greater threat (and in case anyone thinks such behaviour is obviously a thing of the past, Tokyo's notoriously racist mayor gave a speech a few years ago urging the euphemistically-named Self-Defence Force to be ready to round up foreigners in the event of a quake, cos we are liable to riot).

Earthquakes are of course unrelated to climate change, but typhoons are a little closer to my area of research. It's certainly not my field, but from what I've read, there doesn't seem to be any really solid evidence of anthropogenically-induced increases in strength or frequency of tropical storms. There are plausible arguments (supported by modelling studies) that such effects may occur, but the natural variability is too high to see anything in the data. This very new paper has stirred up the debate a bit, but it's surely not going to be the final word on the subject.

Last year Japan was hit by 10 or 11 typhoons, nearly double the previous record of 6, and way above the typical 3 or so. The country seems to cope pretty well with them. When one is forecast to come close, people in the area tend to shut down and stay home for the day as much as possible. The infrastructure - drainage and buildings - generally copes very well, and there is rarely more than the odd person who ventures out at an inopportune time, or who gets buried under a landslide. Sorry if that sounds flippant - but it really doesn't seem to be a big deal usually, just a few hours of disruption to trains which seems quite nostalgic for us UK ex-pats. Last year, there was a particularly bad one (Typhoon Tokage) which killed at least 80 - that really was unusual (worst in 25 years), but still only represents about 3 days' worth of roadkill or (astonishing but true) a typical day's suicides here. I think it's important to keep a sense of perspective on the risks we face.

Natural disasters are not unique to Japan, of course. San Francisco is probably also due a big earthquake, and Florida has been getting plenty of hurricane action recently. UK residents have to make do with Tim Henman's Wimbledon exploits, and the England cricket team :-) The combination of typhoons and earthquakes keeps the power of nature high in the public consciousness here. Once a year we have "Disaster Prevention Day", when there are plenty of practice drills etc - of course we cannot prevent the event itself, but the consequences can be ameliorated both by increasing the robustness of the infrastructure (not just making sure that buildings are strong and fire-resistant, but being careful to keep large bookcases and other heavy furniture away from beds) and by having plans for the immediate aftermath, eg storing a few days worth of food and water so as to relieve pressure on the emergency supplies. Japan is a rich country, which means that the financial costs of natural disasters appear very high, but it also means that the human cost is relatively small - compare and contrast the effects of a recent hurricane which hit Haiti and the Dominican Republic on its way to Florida for a graphic demonstration of this. Roger Pielke Jr's blog has lots of posts and links to his papers on the significance of vulnerability to hurricanes, and the Bam earthquake in Iran killed about 25,000, despite only having a magnitude of about 6.5 - the mud-brick houses simply turned into heaps of earth, burying people alive. By being reasonably well prepared, we can usually prevent a disruption from turning into a disaster.

By the way, rumour has it that the Earth Simulator is built to be highly earthquake-resistant, but they didn't worry so much about the adjacent buildings that the researchers use...

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