Kansai International Airport (KIX), located on two artificial islands in Osaka Bay, Japan, is grappling with significant subsidence issues. Once celebrated as an engineering marvel upon its opening in 1994, the airport is now sinking into the bay, raising concerns about its long-term viability and resilience against natural disasters. The airport was initially designed to float on a soft seabed using advanced ground improvement techniques. However, the rate of subsidence has exceeded initial predictions, with the surface of the island dropping 3.84 meters and a total of 13.6 meters since construction began in 1980.

The ongoing sinking poses a threat to the airport’s future, as its soft clay foundation struggles to support the massive structure. Rising sea levels and natural forces are exacerbating the problem, drawing this engineering feat closer to potential disaster. Despite these challenges, Kansai International Airport has maintained a stellar reputation for efficiency and service. In 2024, it was recognized as the world’s best airport for luggage handling, having maintained a perfect record for over a decade.

KIX was initially developed to alleviate congestion at Osaka’s other airports and has since grown into a major aviation hub, serving approximately 30.6 million passengers traveling to 91 cities across 25 countries in 2024 alone. The airport’s vulnerability was starkly highlighted during Typhoon Jebi in 2018, which caused severe flooding and temporarily shut down operations.

In response to these challenges, engineers are working diligently to stabilize the structure and ensure its sustainability. Over $150 million has been invested in strengthening seawalls and installing vertical sand drains to relieve water pressure beneath the islands. Recent data from December 2024 indicates that while some areas have stabilized with only minor subsidence, others continue to experience significant ground settlement.

The situation at Kansai International Airport underscores the complexities of building on artificial islands and highlights the need for ongoing innovation and investment to safeguard such critical infrastructure against environmental threats.