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Editorial: Measures needed to strengthen flooded Kansai International Airport

Kansai International Airport in western Japan has suspended operations after the facility on an artificial island in Osaka Bay was flooded by a storm surge from Typhoon Jebi. The typhoon was very strong, but the damage left by the storm highlighted the substantial vulnerability of the international airport.

The airport was constructed in 1994 on reclaimed land 5 kilometers off the coast of southern Osaka Prefecture. The island is connected to the mainland by a 3.8-kilometer-long bridge.

The storm surge, coupled with high tides, rose to a record high of 3.29 meters in the waters off Osaka, and this flooded one of the two runways and the terminal building. Moreover, a tanker smashed into the connection bridge and damaged the girder, closing the bridge and isolating the airport completely. As many as 8,000 passengers and others had to spend a night inside the facility. The incident once again showed the flaws of an airport on the sea.

The seabed on which the airport was constructed is soft, and the facility has sunk 3 to 4 meters since its construction. Buildings were supported by jacks to avoid sinking. Because of this situation, experts warned about the danger of flooding by typhoons and other natural disasters and the airport becoming marooned. As the year's 16th typhoon in 2004 broke fences and roads at the airport, seawalls around the facility were elevated by 2.2 meters.

The higher seawall was designed to block the equivalent of the historic storm surge of 2.93 meters recorded when Typhoon Nancy hit the area in 1961. But the surge this time was beyond the previous record, and the damage was extensive. A thorough review of what happened is essential.

The area faces the possibility of a massive earthquake along faults under the Nankai Trough running off central to southern Japan, but current estimates for damage from such a megaquake to the international airport show the possibility of flooding is "extremely low." Tidal surges higher than the one experienced this time could strike depending on the magnitude of the temblor.

The operator of the airport should take measures against the transport hub's vulnerability by strengthening the seawalls and cut-off walls to completely prevent flooding. To prepare for the airport's isolation, inspections should be strengthened to check if evacuation areas and emergency supplies are secured.

During the last fiscal year, Kansai airport received 28.8 million passengers and saw about 188,000 takeoffs and touchdowns, marking new records. It is a hub for mass transportation and Japan's western gateway to overseas locations.

A long closure of the airport will curb the upsurge in foreign visitors and adversely affect corporate activities and the nation's economy as a whole. An emergency plan is needed to utilize nearby airports such as ones in Osaka or Kobe.

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