More than 100 billion USD plan to protect Tokyo safely

Tokyo was once a pioneer in modernization, introducing bullet trains while much of the world still relied on steam locomotives. Tokyo was also at the forefront of the electronics industry before Silicon Valley became famous. The city is also a testament to engineering wonders that defy all destructive forces.

However, beneath Tokyo’s resilient exterior lies a megalopolis always teetering on the brink of disaster. Tokyo’s geography makes the city a dangerous place to live. Located on the Pacific Ring of Fire, the Japanese capital is located at the intersection of four tectonic plates, so this is one of the most earthquake-prone regions in the world. Volcanic activity is also a constant threat, with 114 active volcanoes across the country. Storms and tsunamis from the Pacific Ocean further exacerbate the above risks.

Tokyo itself is located on a vast plain, an ideal location for a population of more than 40 million people. But the city’s expansion also makes it vulnerable to natural disasters. Tokyo has experienced many earthquakes throughout its history. Now, as climate change and urban density increase the threat, the risk is higher than before.

In December 2022, the Tokyo metropolitan government introduced the Tokyo Resilience Project, a $109 billion initiative designed to fortify the city against a range of threats. This ambitious plan, which will take place over 18 years, is one of the largest civil defense projects in history. From reinforcing undersea cables to building massive flood tunnels, the project aims to protect the city from every conceivable disaster.

Evacuation routes were mapped with great precision and rivers were widened to accommodate sudden rising waters. Engineers also created a digital twin of the city, a cloud-based simulation that displays real-time data, to monitor environmental conditions and traffic flows.

The measures in the project go beyond traditional infrastructure. The green space spanning more than 2 square kilometers was developed to provide a place to rest during times of heat and epidemics. Many cycling routes and riverside walkways were introduced to ease public transport congestion. At the same time, durable electricity and communications networks are also in place to prevent blackouts, ensuring that even in the worst of situations, Tokyo remains connected.

Towering on the horizon, Mount Fuji serves as both a national symbol and a reminder of Tokyo’s volatile nature. An eruption could blanket the city in ash, disrupting the daily lives of millions of people. The Tokyo Resilience project includes detailed plans to quickly evacuate the city and provide shelter for those affected.

Despite its continuous expansion with concrete construction, Tokyo’s character is closely tied to water. The decision to leave the capital from Kyoto was partly influenced by its abundant waterways. More than 100 rivers and canals flow through the city, of which the most prominent in the central area is the huge spiral moat surrounding the Royal Palace.

But what helped Tokyo develop also exposed the city’s weaknesses. Flooding is a constant and dangerous threat to megacities. One-fifth of central Tokyo (124 km2) is below sea level. To solve this problem, Tokyo Resilience Project takes bold measures to protect the city. The breakwater was raised to prepare for a 60 cm rise in sea level by 2100,

The challenge doesn’t stop there. Bordered thousands of kilometers by the Pacific Ocean to the south, Tokyo experiences storms that draw strength from the warm northern current, bringing torrential rain that floods streets and waterways. Although storms are nothing new, the urban heat island effect and climate change are making cities more like subtropics, and storms are becoming more frequent and severe. Over the past 40 years, the number of heavy rains in Japan has nearly doubled.

Flooding has long been a part of daily life in Tokyo. In 1992, the city implemented a special initiative to deal with this situation. G-Cans (G-Cans) are a massive underground flood water management system. Consisting of 5 extremely large storage tanks, the system collects flood water from nearby rivers and leads it through 6.5 km of tunnels into concrete tanks.

The “concrete church” complex is located at a depth of 50 m underground, 25 m high, 177 m long and 78 m wide. Able to pump 200 tons of water per second, the facility cost $2 billion to build and took 17 years to complete. But this engineering wonder is still expanding to double its capacity through the addition of new diversion channels and tunnels. The goal is to create a 13km network, among the largest in Japan.

The tunnel construction process requires equally large equipment. A tunnel boring machine (TBM) with a diameter of 12 m and a weight of 2,800 tons was used to dig the canal. The equipment not only digs the soil but also installs reinforced concrete rings on the tunnel wall to stabilize the surrounding ground. The TBM uses a pressure system to balance land and water, ensuring stability as the machine moves forward. In addition, the machine’s cutting head is equipped with many carbide rotary drill bits, 48 ​​times harder than standard materials, allowing the device to penetrate reinforced concrete walls.

Once operational, the expanded system will divert 1.4 million cubic meters of rainwater from Tokyo’s rivers during storms. Water is concentrated in the reservoir until the river level recedes, then safely discharged into the sea.

G-Cans is just one part of a larger network of 28 lakes spread across Tokyo, with seven more facilities under construction. When completed, the system will be able to treat 100mm of rainwater per hour, more than London receives in two months. Without this system, the consequences would be very serious. Businesses, homes and essential infrastructure will face flooding, paralyzing one of the world’s largest cities.

Meanwhile, the threat of earthquakes seems ever-present. The National Institute for Earth Sciences and Disaster Rehabilitation (NIED) operates MOWLAS, a massive seismic monitoring system with more than 2,000 sensors on land and undersea. It was this early warning system (established after the 1995 Kobe earthquake) that was a key line of defense, providing Tokyo with precious time to prepare for the next tremor.

Just before noon on September 1, 1923, a 7.9 magnitude earthquake occurred 50 km southeast of Tokyo. More than 142,000 people died and nearly 2 million people lost their homes. Subsequent fires turned 33,000 square meters in Tokyo into ash. The Great Kanto Earthquake was one of Tokyo’s most devastating natural disasters. In 1995, the city of Kobe was also destroyed by a 6.9 magnitude earthquake. In 2011, the nuclear meltdown at the Fukushima plant was the result of the Tōhoku earthquake and tsunami.

Seismic activity in Japan is measured on the Moment Magnitude Scale, with each level 10 times stronger than the previous level. Levels above level 4 threaten homes, and earthquakes stronger than level 9 release enough energy to power the United States for 2,000 years. Nearly 600 earthquakes of level 4 or higher will take place in Japan in 2024, raising fears that an event similar to the Great Kanto earthquake may reoccur.

Although earthquakes cannot be prevented, the group’s resilience lies in their preparations. At NIED, the research team is studying early warning signs with a 200-ton machine called Giant Rock Friction Apparatus. This machine simulates the sliding process of tectonic plates, helping scientists understand the physics of earthquakes and collect important data for prediction systems. NIED also operates E-Defense, the world’s largest earthquake simulator, which can recreate the conditions of a level 7 earthquake. These advanced technologies make Japan a world leader in engineering. earthquake prevention.

Tokyo’s skyscrapers are the clearest proof. Mori JP Tower will be completed in 2023, equipped with an independent energy supply, food storage for thousands of people and a system to maintain operations after natural disasters. The building’s earthquake-resistant structure includes more than 600 oil dampers and wall dampers that help convert seismic energy into heat, stabilizing the building. Wooden house neighborhoods that were once a source of fire during the earthquake have been upgraded with fireproof walls and underground power lines. More than 400 bridges like the Eitai Bridge are reinforced to withstand earthquakes from all directions, reflecting the meticulous planning behind the city’s safety measures.

The Tokyo Resilience Project is unprecedented in both scale and goals. From underground water tanks and seawalls to seismic-resistant skyscrapers, the city is preparing to prevent any possible disaster and develop sustainably.