TOKYO — Japan has ordered a nationwide inspection of 49 tunnels after the collapse of a highway tunnel near Mt. Fuji killed nine people and crushed cars with almost 400 tons of concrete in the nation’s worst tunnel disaster in 16 years.
The Ministry of Transport ordered the inspections to be conducted by Dec. 12, according to a statement on the ministry’s website. About 270 concrete slabs, each weighing 1.4 tons, fell from the ceiling of the Sasago tunnel on the Chuo expressway about 50 miles west of Tokyo early Sunday morning.
Japan’s highway network includes more than 1,500 tunnels, with a quarter of them more than 30 years old, according to the Transport Ministry. The 3-mile Sasago tunnel, which was built in 1976, may have collapsed because of age or seismic activity, according to Central Nippon Expressway, which operates the toll road.
‘‘The bolts may have been getting old or there was some impact from earthquake activity,’’ said Satoshi Noguchi, a spokesman for Central Nippon. A final assessment on the cause of the collapse will be given after police and Central Nippon engineers complete their investigations, he said.
Some bolts securing the strap supporting the tunnel ceiling were found to be missing, Noguchi said. The Sasago tunnel in Yamanashi prefecture was last inspected by Central Nippon in September, according to the Transport ministry, and no defects were found.