Key Takeaways
• Kansai Airport sinks due to soft clay, with islands subsiding 6cm and 21cm annually in 2024.
• A $609 million renovation boosts resilience, raising seawalls, runways, and reinforcing infrastructure.
• Airport serves over 30 million passengers yearly, staying operational despite subsidence challenges.
Kansai International Airport Faces Ongoing Subsidence: How Japan’s Offshore Hub Stays Afloat
Kansai International Airport, located on an artificial island in Osaka Bay, remains one of Japan’s busiest and most important air gateways. As of June 2025, the airport continues to face a unique challenge: subsidence, which means the ground beneath it is sinking. Despite this, Kansai International Airport is fully operational, serving over 30 million passengers each year and connecting Japan 🇯🇵 to 91 cities in 25 countries. The story of how the airport manages this problem, and what it means for travelers, workers, and the future of airport design, is both complex and important.
What’s Happening at Kansai International Airport?
Kansai International Airport was built on two artificial islands in the 1990s to solve land shortage and noise problems in Osaka. Since its opening in 1994, the airport has been sinking due to the soft clay and sediment beneath the islands. This process, called subsidence, was expected, but the rate and amount have been greater than engineers first predicted.
- First Island: Sinking at an average of 6 centimeters per year (measured at 17 points in 2024)
- Second Island: Sinking faster, at 21 centimeters per year (measured at 54 points in 2024)
Since construction began, the first island has dropped a total of 3.84 meters (12.6 feet), while the second island has sunk 17.47 meters (57 feet). Initial estimates in 1994 predicted only 8 meters of sinking over 50 years, but this was surpassed within the first decade.
Why Is the Airport Sinking?
The main reason for the subsidence is the thick, water-filled clay under the islands. When the heavy landfill and airport structures were placed on top, the clay compressed more than expected. Even with advanced engineering, including millions of drainage pipes and boreholes to solidify the ground, the weight was too much for the soft layers deep below.
How Are Officials Responding?
Despite the ongoing subsidence, airport officials and Japanese authorities say the situation is “manageable.” The rate of sinking has slowed, and there have been no emergency closures or major disruptions. The airport operator, Kansai Airports, works closely with academic experts and engineers to monitor the situation and take action when needed.
Key Steps Taken to Manage Subsidence:
- Continuous Monitoring: Dozens of points across both islands are checked regularly for changes in ground level.
- Seawall Reinforcement: Over $150 million has been spent to raise and strengthen seawalls, protecting the airport from flooding and storm surges.
- Runway Elevation: Runways are gradually being raised using special asphalt that resists damage. This work is done mostly at night to avoid interrupting flights.
- Adjustable Steel Pillars: The terminal buildings rest on 900 steel pillars that can be adjusted. Maintenance teams recalibrate up to 10 pillars per shift to keep the buildings level.
- Hydraulic Jacks and Concrete Foundations: These tools help lift and support parts of the airport as needed.
- Advanced Drainage Systems: Pipes are in place to handle up to 55 millimeters of rain per hour, helping prevent water from pooling on the islands.
The $609 Million Renovation Project
To keep Kansai International Airport safe and modern, a major renovation project is underway. This $609 million effort aims to improve facilities, increase capacity, and make the airport more resilient against both subsidence and extreme weather. The project includes:
- Upgrading passenger terminals
- Improving baggage and cargo handling systems
- Strengthening runways and taxiways
- Further raising seawalls and flood barriers
These upgrades are designed to ensure the airport can continue to serve millions of travelers and remain a key hub for airlines like ANA, JAL, and Nippon Cargo Airlines.
What Do the Experts Say?
Academic and engineering experts are deeply involved in monitoring and advising on the situation at Kansai International Airport.
- Hiroo Ichikawa, Urban Planning Professor at Meiji University: “It is sinking by less than 10 cm a year now, but that is slowing and manageable.” He also points out that the airport’s experience offers valuable lessons for future offshore projects.
- Hiro Ishikawa, Meiji University: Explains that building offshore was necessary because of land shortages and noise concerns in Osaka. However, he notes that putting critical infrastructure underground was a mistake, as shown by the 2018 flooding.
- Engineering Community: Warns that without continued intervention, especially on the second island, parts of the airport could eventually fall below sea level.
Lessons from Typhoon Jebi
In 2018, Typhoon Jebi caused $13 billion in damage to Kansai International Airport. Flooding stranded 5,000 people and highlighted the risks of building on artificial islands. Since then, the airport has moved critical infrastructure above ground and raised seawalls by 2.7 meters to better protect against future storms.
How Does This Affect Travelers and Workers?
For most travelers, the subsidence at Kansai International Airport is invisible. Flights continue as normal, and there have been no major disruptions. However, the ongoing work to keep the airport level and safe means:
- Regular maintenance and construction are a constant presence
- Some areas may be closed temporarily for repairs or upgrades
- The airport’s long-term future depends on continued investment and careful management
For workers, especially those in maintenance and engineering, the challenge is ongoing. Teams must constantly monitor ground levels, adjust pillars, and plan for future repairs. The cost of these efforts is high, but necessary to keep the airport running smoothly.
Comparisons and Global Lessons
Kansai International Airport is not the only airport built on an artificial island, but it is the largest and most famous example. Chubu Centrair Airport, also in Japan 🇯🇵, was built on a smaller artificial island and has had much less trouble with subsidence. Experts say this is because of better soil conditions and lessons learned from Kansai.
The experience at Kansai serves as a warning for other countries considering similar projects. Building on soft, water-filled clay is risky, and even the best engineering cannot fully stop the ground from sinking. Ongoing monitoring, flexible design, and the ability to adapt are key to long-term success.
Policy and Financial Implications
The Japanese government continues to support Kansai International Airport with funding for upgrades and disaster preparedness. No new emergency policies have been announced in June 2025, but the focus remains on:
- Investing in infrastructure to prevent flooding and damage
- Consulting with academic and engineering experts
- Preparing for future storms and climate risks
The cost of maintaining the airport is high. The original construction cost about $20 billion, and hundreds of millions more have been spent on repairs and upgrades. The current renovation project alone is budgeted at $609 million.
Future Outlook: What’s Next for Kansai International Airport?
Subsidence at Kansai International Airport is expected to continue, though at a slower rate. Some experts predict that parts of the airport could fall below sea level by 2056 if current trends continue. However, with ongoing investment and careful management, the airport is not in immediate danger.
The renovation project aims to make the airport more resilient, but the need for constant monitoring and repairs will remain. The situation at Kansai is a reminder of the challenges of building large infrastructure on soft ground, especially as climate change brings more extreme weather.
Key Takeaways for Stakeholders
- Travelers: Kansai International Airport remains safe and fully operational. Travelers should expect some ongoing construction and maintenance, but no major disruptions.
- Airport Workers: Maintenance and engineering teams play a critical role in keeping the airport level and safe. Their work is ongoing and essential.
- Government and Policy Makers: Continued investment in infrastructure and disaster preparedness is necessary to protect the airport and its users.
- Engineers and Planners: Kansai’s experience offers important lessons for future offshore projects, especially about soil conditions, flexible design, and the need for regular monitoring.
Practical Guidance for Readers
If you plan to travel through Kansai International Airport, check the airport’s official website for the latest updates on facilities and any ongoing construction. For those interested in the technical details or future plans, the Japanese Ministry of Land, Infrastructure, Transport and Tourism (MLIT) provides official information and updates on airport projects. You can find more details on the MLIT’s official Kansai Airport page.
Why Does This Matter for Immigration and Global Mobility?
Kansai International Airport is a vital link for people moving to and from Japan 🇯🇵, whether for work, study, or family reasons. Its continued operation ensures that Japan remains connected to the world. The airport’s challenges and solutions also matter for anyone interested in how countries build and maintain the infrastructure that supports global movement.
According to analysis by VisaVerge.com, the ongoing renovation project and careful management of subsidence at Kansai International Airport show how important it is for countries to invest in resilient infrastructure. This is especially true as climate change and urban growth put more pressure on airports and other critical facilities.
Conclusion: A Balancing Act Between Nature and Engineering
Kansai International Airport’s story is one of bold engineering, unexpected challenges, and ongoing adaptation. While the airport continues to sink, the rate has slowed, and officials are confident that with continued investment, it will remain a key hub for years to come. The lessons learned here will shape how airports and other large projects are built on soft ground in the future.
For travelers, workers, and anyone interested in global mobility, Kansai International Airport stands as a reminder that even the most advanced projects must respect the forces of nature—and be ready to adapt when things don’t go as planned.
For More Information
- Visit the Japanese Ministry of Land, Infrastructure, Transport and Tourism (MLIT) Kansai Airport page for official updates and technical reports.
- For the latest news and travel advisories, check the Kansai Airports official website.
- For in-depth analysis on immigration and infrastructure, VisaVerge.com offers expert coverage.
Actionable Steps:
– If you’re traveling through Kansai International Airport, check for updates on construction or maintenance.
– For those interested in airport design or engineering, review official reports and academic studies on subsidence.
– Policy makers and planners should consider Kansai’s experience when planning future offshore or large-scale infrastructure projects.
Kansai International Airport’s ongoing renovation project and careful management of subsidence show that with the right planning and investment, even the biggest challenges can be managed—keeping Japan 🇯🇵 connected to the world.
Learn Today
Subsidence → The gradual sinking or settling of the ground surface caused by soil compression or removal.
Artificial Island → A man-made landmass created by filling or reclaiming land from water bodies.
Seawall → A protective barrier built along the shore to prevent flooding and storm damage.
Drainage Pipes → Systems installed to channel and remove excess water to avoid flooding and soil weakening.
Hydraulic Jacks → Mechanical devices used to lift and support structures by applying controlled force.
This Article in a Nutshell
Kansai International Airport faces sinking ground from soft clay beneath artificial islands. Despite this, it remains fully operational, serving millions with ongoing costly maintenance and a $609 million renovation to enhance resilience against subsidence and weather, illustrating complex engineering balancing nature and infrastructure needs.
— By VisaVerge.com
