Japan plans to build a 250-mile chain of cement seawalls up to five stories high to protect the country against future tsunamis. The project hopes to stop a repeat of the devastating March 2011 tsunami that killed about 19,000 people, destroyed much of Japan’s northeastern coast, and led to the Fukushima nuclear disasters. The government announced the plan, which was later nicknamed “The Great Wall of Japan” by detractors, a few months after the tsunami, according to the Guardian. Japan’s plan to build more than 400 seawalls is estimated to cost at least $6.8 billion and has already begun in the worst-hit areas. A number of people are in favor of the multi-billion dollar seawall project because it will create some jobs. The governing Liberal Democratic Party, which is supported by backers in business and construction, has made the deal easy for the industry. But critics say the walls do not guarantee safety. When the 2011 tsunami smashed into Fudai in northeastern Japan, a concrete wall sheltered the village and all 3,000 residents survived. But most walls along the northeast coast did not fare as well, including a $1.6 billion wall built along the city of Kamaishi that crumbled from the ocean’s impact. More than 1,000 people died there. “The problem is that you can’t predict how high the next tsunami will be, so seawalls can never give you 100% security,” Christian Dimmer, an assistant professor in the urban studies department at Tokyo University, said to the Guardian. “There will always be a risk.” Opponents argue that seawalls will make people more complacent. Some of the 19,000 people killed in the 2011 tsunami were swept away by the waves after failing to heed warnings to evacuate. Hiroko Otsuka, who grew up near Koizumi, where an already existing embankment is being fortified, told the Economist that seawalls make the situation worse. In 2011, Otsuka said her mother and her brother’s two children were killed. They could have been saved, she believes, if they had evacuated to the hill behind their house, but they thought the seawall would protect them. After the 2011 tsunami, some displaced residents are moving to higher ground. In Koizumi, a wall is being designed to protect a village that has been moved almost two miles inland. The 48-foot-high seawalls being built there for a cost of $230 million could end up protecting nothing more than rice paddies. credits: buzzfeed
Good deal for $6.8 billion. At Fudai a wall saved 3000 people, so assuming each person is worth $1m in economic output, so that's $3 billion already.
It sounds like a good idea, but IMHO, it seems more a capital project to generate jobs than provide real protection. Rather than build a continuous sea wall, what Japan seriously needs to do is to protect its population centers and vital or critical infrastructure (cough... nuclear plants, cough...) from damage. Further, consideration in the future for capital projects should center on locations that are naturally protected against both earthquake AND tsunamis. Additionally, all new housing being built in tsunami prone areas should have underground 24 hour shelters in the basement, where those that become trapped can refuge until rescued. In this way, a house can be washed away, but the inhabitants can still be safe underground and rescued once the water recedes.
IMHO, Japan faces a variety of problems with earthquakes and tsunamis and cannot be looked upon simply by throwing money at it which, to those that don't know, Japan had done for years. Sea Walls, as well as Tetrapods, or those huge four legged concrete blocks, have lined the Japanese coastline with debatable effectiveness. The question here before us, is the ultimate cost versus efficacy of tsunami control. Areas that are devoid of human presence don't necessarily need to have tsunami protection. But areas of high population density or high economic value by default will almost always necessitate a huge expenditure. In essence, high density areas have zero evacuation value. That is, the areas are so packed with people and essential enterprise that it is a practical impossibility to even consider evacuating as such activity would literally take many days or even weeks. A tsunami can strike in a matter of minutes or hours. Also, what has to be viewed with a sense of economics is the overall value of the protection. If it's only a matter of protecting lives, then it becomes relatively easier, as devices can be made to only allow people to be safe guarded. An example of this would be to have Tsunami "safe" zones made from structures that would be impermeable to not only tsunami water, but the rolling field of event generated debris that would crush everything in its path. A reinforced concrete building built on top of relatively elevated ground would do this at minimal cost. If an alert was issued, people need only get to the building and they know they will be safe. However, protection of property would require much more financing as it would require physical exclusion zones where tsunami damage cannot travel. This type of protection would entail heavy walls to block not only water but also floating debris, some of which can weigh tons. Additionally, existing structures which, by their nature, require hardiness against earthquake and tsunami may be retrofitted to allow for emergency use as a refuge from tsunamis. A perfect example would be the elevated highways that travel through urban areas. If strategically placed emergency stairs were available along the length of elevated highways, people can rush up onto the relatively safe platforms and shelter during a catastrophe. Alternatively, Japan needs to consider removal of it's vulnerable assets away from potential impact zones, but that may not be practical given the already established densities of its civil architecture. In essence, there are no real win - win scenarios, but rather everything must be calculated in risk vs benefits terms. Whether a risk is acceptable or not obviously, is worthy of lengthy debate depending on what the involved parties each have at stake. ADDENDUM: It looks like many in Japan have already taken this simple idea seriously: https://www.youtube.com/watch?v=wDh_kiVjmw4 https://www.google.com/search?q=TSU...uIHIBA&ved=0CB4QsAQ&biw=1536&bih=726&dpr=1.25
