Great tsunami wall of Japan: boon or boondoggle?

Not everyone is convinced sea walls being built by government will stop tsunamis killing people

Like hundreds of communities along Japan's northeast coast, the village of Koizumi exists on maps only. Five years ago, an earthquake under the Pacific Ocean erupted with the force of a million tons of TNT, triggering towering waves that carried away nearly 18,000 people.

The deluge flattened Koizumi and drowned 40 of its 1,800 residents. In a country with about 20 per cent of the world’s strong quakes, and pummelled by tsunami roughly every seven years, survivors know some day it will almost certainly return.

Japan’s government announced a tried-and-tested solution: pouring concrete. A few months after the March 2011 disaster, it pledged to build hundreds of sea walls and breakers in the three worst hit prefectures, for about €6 billion.

Many more are on the drawing board. A joint report by the ministries of agriculture and land says 14,000km of Japan’s 35,000km coastline requires tsunami protection. “It’s madness,” concludes Masahito Abe, a Koizumi resident.


The solution is controversial, not least because the evidence for their effectiveness is mixed, at best. Even before the 2011 disaster, at least 40 per cent of Japan’s coastline was lined with concrete protection.

Fudai, a village behind a giant concrete shield once condemned as a costly boondoggle, escaped unscathed in 2011. But in the city of Kamaishi, a €1.4 billion breakwater listed in the Guinness Book of Records as the world's largest, crumbled on impact with the tsunami.

Nearly 90 per cent of the seawalls along the northeast coast suffered similar fates, a blow to a country considered among the planet's best protected from the fury of natural disasters. Critics say they made the impact of the deluge in many places worse. "There is simply no guarantee that sea walls will stop every single tsunami," says Nobuo Shuto, a tsunami engineer at Tohoku University.

The sea wall failure was most striking at the Fukushima Daiichi Nuclear Plant. Its operator, Tokyo Electric Power Co, has continued to argue that the 13m tsunami that overwhelmed the plant's cooling system following the earthquake was "beyond all normal expectations". An internal Tepco report in 2008, however, predicted a maximum tsunami of 15.7m.

Shuto, though not against all sea walls, is among a growing number pushing for a rethink. Surprisingly, perhaps, Akie Abe, the prime minister’s wife, is among them. She gingerly spoke out against a plan signed off by her husband, saying it could damage tourism and destroy local ecosystems. But she has had little success convincing local authorities to change course – sea walls bring local jobs and riches to Japan’s powerful construction companies.

The same inflexible response has greeted residents across the northeast, says Hiroko Otsuka, a campaigner who grew up near Koizumi. She says bureaucratic decisions made and funded from Tokyo are almost impossible to reverse. "There is no mechanism to make it happen, no matter how many residents, environmentalists or academics are against it."

Koizumi’s 14.7m wall, with a price tag of 230 million yen (€1.8m), will shelter a community that is no longer there. The village has moved 3km inland. Essentially, the money will protect rice paddies, says Abe.

More puzzlingly, the land ministry admits the new structures are not designed to withstand the sort of seismic event that occurred in 2011. That quake is considered a once-in-a-1,000-year calamity and nothing could block it, said a spokesperson for the ministry. Koizumi’s wall is less than half the size of the highest wave that hit then. Still, the walls will save lives, and many residents demand them, said the ministry.

Otsuka disagrees, saying residents sheltering behind the walls are lulled into a false sense of security, and lose the ability to read the sea. Tsunami warnings are common in the northeast: there was one a few days before March 11th, 2011.

The 2011 deluge killed Otsuka’s mother and her brother’s two children. They could have been saved if they had fled 10m up a hill behind their house, she insists. They didn’t run because they thought the sea wall would protect them. Abe was more fortunate: two decades ago he moved his family to a hill back from the sea. “We lived when so many others didn’t,” he laments. “It makes my heart hurt to think about that.”