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Japan is a country comprised of a series of islands in the western Pacific Ocean, and is an example of an arc-trench system, situated in a subduction zone between the margins of 4 tectonic plates: the North American, Eurasian, Philippine and Pacific plates (GLGArcs, n/a). Many of the islands are volcanic (the largest island being Honshu - home to Tokyo, Kyoto and Hiroshima) and are therefore characterised by a multitude of natural hazards. These include earthquakes, volcanic eruptions, tsunamis, mass movement and typhoons.
In contrast to Ladakh, which is a low-income region, Japan has a GDP per capita of £25,362 and is currently the 3rd largest economy in the world. There is a huge difference in adaptability and mitigation between Ladakh and Japan, Japan has some of the most complex and expensive disaster mitigation management - although this is unequal between different regions.
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| Tectonic plates margins in Asia. Source |
Tokyo has been listed as the top city most at risk of natural hazards in the world, with the amount of vulnerable people in the Tokyo-Yokohama exceeding over 57 million (USA Today, 2013). However, Tokyo, due to its high wealth and capital manages to mitigate many of the hazards effectively. For example, in part of the response to the Tohoku earthquake in 2011, a 10 year project to promote earthquake-resistant joints was undertaken, whereby the replacement of 5,000 km in length of existing joints would be replaced by earthquake resistant ones. So far, the share of earthquake resistant joints has exceeded 35% (Mochizuki, 2015).
Additionally, Tokyo has implemented an emergency water supply system, tested for quality each year, which would be able to supply the whole population of Tokyo should a natural hazard strike (Waterworks, 2012). In total, there are approximately 203 emergency supply bases across Tokyo (Mochizuki, 2015). These sources are reliant on community participation, with Tokyo Waterworks implementing training with local residents at each supply base. It provides a stark contrast to Ladakh, where any high magnitude earthquake would completely cut off water supply.
I have already touched upon Japanese ‘earthquake-proof’ building design in a previous post, but Japan is now turning much of its attention to tsunami mitigation. A 400 km long sea wall along the North-East of Honshu, near Sendai is currently being constructed (where the devastating magnitude 9 Tohoku earthquake and tsunami hit in 2011 - but more of that in my next post!) to protect residents and infrastructure from flooding effects of tsunamis and typhoons (Gough, 2015). This sea wall - dubbed the ‘Great Wall of Japan’ - when finished, will be 5 stories high and is set to cost $6.8 billion. However, there have been many criticisms of this use of hard engineering methods, as opposed to soft engineering such as afforestation. Although afforestation will not stop a tsunami, it could help to slow down the speed of waves and prevent some debris being washed back out to sea (RT, 2015).
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| Building of the 'Great Wall of Japan'. Source |
Sea walls are fairly controversial in Japan; they are known to negatively affect oceanic wildlife by reducing biodiversity via loss of habitat (Galbraith et al., 2002), and are seen as unsightly. In some areas sea walls have been effective flood defences such as in Fundai; in others they have not. A breakwater which cost over $1 billion to construct to protect the city of Kamaishi instantly crumbled on impact during the Tohoku tsunami in 2011, killing around 1,000 people (The Economist, 2014). But, as climate change pushes sea level higher, and the frequency of natural hazards begins to increase, this may be the only viable solution that the government pursues - they are already planning to protect a further 14,000 km of coastline once the sea wall has been completed. What is your opinion on sea walls as a flood defence? Do the negative impacts to the environment outweigh the possible benefits to community safety or vice versa? Next posts will include: the Tohoku earthquake and tsunami, climate change and risk/vulnerability in Japan, and the social inequality in hazard mitigation.
Hi Celia! A very interesting blog post. I believe that Japan is a great example to emphasise the differences in adaption against climatic hazards compared to developing nations. Developed countries have a greater ability to reduce natural hazard impacts as they have the money to prepare against them.
ReplyDeleteI believe that building a wall 5-storeis high is a relatively extreme measure, which will not only impact the environment but will also be anaesthetic. Wouldn't you agree? Also, the fact that it is 5 stories high equates to around 15 metres, however (correct me if I am wrong) I believe the last tsunami in Japan was twice almost 3 times the size of this. Hence it is very likely that other tsunami events may have the ability to flow over this wall. Furthermore, although I am sure this wall will withstand a lot of pressure, it will be receiving thousands of tonnes of volume at high speed hitting this wall and will also have after shocks of high waves, so I am questioning to what degree this wall will be able to withstand this pressure. Nonetheless, this is just speculation and I may be wrong. However I think the negative environmental impacts in this specific case will outweigh the benefits of the community, as I am unsure to what degree the community will benefit. What do you believe?
Hi Maria - I completely agree, developed countries such as Japan are able to implement more costly hazard mitigation strategies that are most effective against natural hazards than poorer developing countries.
DeleteYes, you're completely right - I think the 2011 Tohoku tsunami reached a total of 40m in height at its peak! Much of the water was able to flow inland, at most, 6 miles, which greatly impacted the area of Sendai. I do believe that this tsunami wall might not really prevent much damage, although I guess for smaller tsunamis less than 15m in height it may be effective. The community in these areas are quite sceptical that the benefits will outweigh the negatives, especially as there are fishermen in this area that will have the fish stock detrimented by the sea walls. It is hard to know what kind of strategy the government should pursue though!
Although costly, another suggestions without many negative implications is to move high densities of population further inland and near the shore have more parks and golf areas I guess. Even though this is highly difficult to achieve as people have been living in their homes for many years and many will be reluctant to move.
DeleteNice post Celia. I'm glad to hear that since 2011 there has been a focus on tsunami mitigation as really the tsunami was the main player in the devastation resulting from that hazard - the earthquake itself almost gets forgotten! I suppose you will be covering this in your next post, but what mitigation measures are suitable for dealing with tsunamis of that scale other than sea walls? We have seen many times in the past (Katrina and Tohoku) that sea walls are pretty pointless if the tsunami is large enough to go over them
ReplyDeleteHi Ben, thanks for your comment :) Yes, the sea walls do seem quite ineffectual, but have had varied success. In Fundai, sea walls really protected the village from the 2011 tsunami, which remained unscathed. So it really does change in how effective they can be. Regarding your question, for a 'soft approach' afforestation, or, 'tsunami forests'as they have been termed, are encouraged. Other than that, breakwaters, river gates, hazard mapping and attempted tsunami prediction and early evacuation are methods currently utilised. I guess, in essence, as proved by Japan, there haven't really been any mitigation techniques that have completely eradicated damage caused by tsunamis!
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