Three years after the March 11 earthquake and tsunami that devastated the Tohoku region, a study of the disaster by professors at the University of Tokyo and Indiana’s Purdue University suggests the region’s hundreds of kilometers of seawalls did almost nothing to save lives, claiming instead it was social ties among community members that “influenced the rates of death during the disaster.”
The analysis, according to a working draft of the paper obtained recently by Kyodo News, “found no support for the argument that the pre-existing seawalls provided any protection against mortality,” which depended to a greater extent on communal bonds.
The study comes as Japan prepares to invest hundreds of billions of yen in seawall construction across the nation, a project that has faced popular opposition from coastal residents who claim the massive edifices block their views of and access to the sea.
Daniel Aldrich, an associate professor of political science at Purdue University, conducted the study with University of Tokyo economics professor Yasuyuki Sawada in an attempt to understand the dramatically different fatality rates — ranging from zero to almost 10 percent — among localities affected by the disaster.
In the study, the scholars looked at a number of potential explanations for the divide, ranging from the residents’ average age (which could make them slow to escape) to the local crime rate and the tsunami heights when they struck each town. They based their work on a survey of publicly available data from all 133 cities, towns and villages affected by the disaster.
Reached by phone Saturday, Aldrich said he had “95 percent confidence” in the findings, which had been vetted by other academics.
“The pre-existing seawalls, to our knowledge, had no measurable impact on mortality, except in a single community,” Aldrich said.
The study also found a high correlation between pre-existing crime rates and mortality during the disaster. Past research has shown low crime rates are a strong indicator of social cohesion. The closer a city’s social bonds, argue Aldrich and Sawada, the more likely residents helped each other during the disaster.
“A municipality which had 15 crimes committed per 1,000 people,” the study claims, “would be expected to have a death rate some 100 times higher than one where there were only one to two crimes per 1,000 people.”
Despite the objections of local residents and their catastrophic failure to protect coastal communities on March 11, 2011, the government is considering building or rebuilding 370 km of seawalls in the Tohoku region alone as part of its disaster recovery effort, according to research done by the Nature Conservation Society of Japan. All told, the group expects the project to cost as much as ¥820 billion.
Aldrich believes better results can be achieved for much less.
“We’re investing so much money in physical infrastructure . . . but, trying to strengthen social capital might be a much more cost-effective way to save lives,” he said.
“The reality was if your neighborhood evacuated as a group and got out the elderly and the infirm and the vulnerable, you didn’t need a 17-meter seawall to save their lives.”
In fact, Aldrich claims seawalls can actually make people less safe by providing a false sense of security and reducing the chance they will evacuate tsunami-threatened areas in a timely manner.
Proponents of the new seawalls cite the example of Fudai, a small town in Iwate Prefecture saved from the March 11 tsunami by an enormous seawall, as a compelling argument for their construction.
But the majority of the currently planned seawalls fall far short of Fudai’s staggering 15.5-meter mark. Even the tallest projects top out at around 14.7 meters, according to government websites of Tohoku’s three coastal prefectures of Iwate, Miyage and Fukushima. Projected seawalls in Fukushima Prefecture, where tsunami triggered the Fukushima No. 1 nuclear disaster, will rise to a mere 8.7 meters.
Although the projects are well-intentioned, “the government hasn’t really thought them through,” said the Nature Conservation Society’s Tomoko Shimura, adding that the costs and benefits of the projects should be explained to people whose livelihoods might be affected by the walls.
During a Diet session on March 12, Prime Minister Shinzo Abe said that he expected “the government to move the project forward while carefully listening to local people’s opinions.”
Based on the results of his study, Aldrich believes Japan should re-examine its recovery priorities: “Did the previous existing seawalls save lives? The answer is pretty clearly no. Will the same level seawall save any more lives if there is the same level of tsunami? I can’t see why it would. There’s no logic behind that.”