Improper operation was to blame for the flooding that trapped 12 miners underground last Sunday in Chaohua Town of Xinmi City, central Henan Province, authoritative said yesterday.

　　The headquarters for rescue work at the Chaohua coal mine found that the major cause of the accident was that the coal mine administration did not carry out a thorough survey of the hydrological and geological conditions in the mining areas before launching the operation.

　　The tragedy occurred at 4:32 pm last Sunday when the heading face of Chaohua colliery was suddenly flooded.

　　The company claimed that investigations after the accident showed that a nearby private coal mine had dug 320 meters into the territory of the colliery, forming a mined-out area of more than 60,000 cubic meters.

　　The mined-out area held an estimated 28,000 cubic meters of accumulated water, which suddenly poured down on Sunday afternoon when mining by the colliery was going on, the investigation showed.

　　(Xinhua)