Xinhua reported that a sudden explosion of rock in a coal mine after a small earthquake in central China killed 4 miners and trapped 57 others in central China's Henan Province on Thursday evening.

The accident happened around 7:45 PM in Qianqiu Coal Mine in the city of Sanmenxia. A total of 75 miners were working in the shaft at the time of the accident, of whom 14 managed to escape.

The State Administration of Work Safety has ordered local authorities to continue verifying the number of miners affected, working out rescue plans and preventing secondary accidents.

The phenomenon known as a "rock burst" occurs when settling layers of earth bear down on the walls of a mine and result in a sudden, catastrophic release of stored energy. Exploding pillars can turn chunks of rock or coal into deadly missiles, and the shock waves alone can be deadly.

The coal mine, with an annual production capacity of 2.1 million tonnes, belongs to Yima Coal Group, a major state owned coal enterprise in Henan.

(Sourced from Xinhua)