Japan’s Kansai International Airport (KIX), built on a man-made island in Osaka Bay, continues to face a persistent sinking issue that has challenged engineers since its opening in 1994. Despite serving over 30 million passengers annually and connecting 91 cities across 25 countries, the airport’s soft clay foundation has led to significant subsidence—12.5 feet on the original island and a staggering 57 feet on the newer expansion island.
The issue came into sharp focus during Typhoon Jebi in 2018, which flooded critical infrastructure and stranded thousands of passengers, prompting a reevaluation of underground system placement. In the past year alone, engineers recorded a 21 cm drop at 54 monitoring points on the second island, underscoring the urgency of ongoing stabilization efforts.
To manage the subsidence, engineers have invested over $150 million in seawall upgrades, elevated key systems above flood levels, and deployed high-precision monitoring systems. While the sinking rate has slowed to under 10 cm per year, projections suggest parts of the airport could fall below sea level by 2056 if climate risks continue to escalate.
Kansai’s experience has informed the design of Chubu Centrair International Airport, which opened in 2005 near Nagoya. Built on more stable ground with elevated infrastructure, Centrair has experienced minimal subsidence and was named the world’s best regional airport for 11 consecutive years.
As Kansai continues to operate at full capacity, its story serves as a global case study in climate-adaptive infrastructure, highlighting the need for resilient design in vulnerable coastal zones.
