The Great Wall of Japan: 400 km of tsunami protection

On March 11, 2011, a massive tsunami struck the coast of Japan, triggering a nuclear disaster and claiming the lives of over 20,000 people. This painful lesson prompted the authorities to build a massive seawall to protect cities and villages from the threat of the sea. However, the Great Wall of Japan has sparked considerable controversy among residents and environmentalists.

A wall of concrete

Seawalls have protected Japan’s coasts for decades, as the country is frequently battered by typhoons. As early as the mid-20th century, a 10-meter-high, 2.4-km-long seawall was erected around Tarō (now part of the city of Miyako). However, it proved too low in the face of the tsunami triggered by the 2011 earthquake – 15-meter-high waves easily overcame it and wreaked havoc inland.

To prevent such disasters in the future, the Japanese government invested over $12 billion in a comprehensive tsunami protection system. The Great Wall of Japan, as the media call it, stretches 396 km in total, with plans to extend it to 430. It consists of segments that reach up to 15.5 meters in height at their tallest points and are anchored in foundations up to 25 meters deep. A widened base is meant to ensure stability in the face of waves, as well as the gradually rising sea level, as occurred in 2011.

Will the Great Wall of Japan protect the islands from the next tsunami?

Some scientists warn that a very tall seawall could turn into a double-edged sword – if it breaks, the water trapped behind the concrete barrier could hit the coast with even greater force, causing more severe damage.

However, the main goal of the Great Wall of Japan is not to stop the next tsunami. According to its designers, it is meant to give residents of coastal towns more time to evacuate. It is believed that in 2011, many victims missed safety by just 1–2 minutes.

The comprehensive protection system for Japan’s northeastern coastline includes not only the concrete structure, but also public education, early warning systems, and safe evacuation routes.

People are protected—but what about nature?

Although the Great Wall of Japan was built to improve residents’ safety, it has not been met with enthusiasm. The concrete wall has blocked sea views and reduced the tourist appeal of many towns, making them resemble prisons. Some communities have openly opposed the construction and chosen to live without protection – but close to the sea.

Environmentalists are also raising concerns. According to a study published in 2018, the concrete wall will harm the coasts by disrupting their geomorphology and limiting sediment transport. These effects could be dramatic for biodiversity. Many marine creatures will also lose vital access to the shoreline, crucial for their survival.

The Great Wall of Japan is not the only idea for protecting the Land of the Rising Sun from the power of the ocean. Alternative solutions include creating tsunami-mitigating parks – green areas with artificial elevations and dense tree cover, which, combined with smaller concrete structures, could weaken the force of waves. Many experts also suggest relocating buildings inland, including imposing a ban on new construction in coastal zones.

In the face of increasing extreme weather events, protecting towns and villages from natural disasters is becoming a growing global challenge. Gray, concrete infrastructure competes with nature-based solutions – and the optimal choice is not always clear.