A mining accident is an accident that occurs during the process of mining minerals or metals. Thousands of miners die from mining accidents each year, especially from underground coal mining, although accidents also occur in hard rock mining. Coal mining is considered much more hazardous than hard rock mining due to flat-lying rock strata, generally incompetent rock, the presence of methane gas, and coal dust. Most of the deaths these days occur in developing countries, and rural parts of developed countries where safety measures are not practiced as fully. A mining disaster is an incident where there are five or more fatalities. Causes Mining accidents can occur from a variety of causes, including leaks of poisonous gases such as hydrogen sulfide or explosive natural gases, especially firedamp or methane, dust explosions, collapsing of mine stopes, mining-induced seismicity, flooding, or general mechanical errors from improperly used or malfunctioning mining equipment (such as safety lamps or electrical equipment). Use of improper explosives underground can also cause methane and coal dust explosions. Worst mining disaster in history On April 26, 1942, during World War II, in the Benxihu (Honkeiko) coal mine in Liaoning Province, China, what is believed to be the worst mining disaster in history took the lives of over 1,500 people. The disaster occurred in an area that is now within the borders of modern-day China, but was at the time part of the puppet state of Manchukuo established by Japan after it invaded and occupied northeast China in the 1930s. The Japanese administrators of the mine forced Chinese labourers to conduct the mining work under harsh conditions. The disaster began with a fire in the mine. In order to suppress it, the Japanese operators cut off air in the ventilation shafts and blocked off the mine so as to deprive the blaze of oxygen. Most workers were not evacuated before these actions, and they were trapped within the sealed-off area of the mine; they suffocated to death as the fire burned off oxygen and led to carbon monoxide poisoning. Once the fire died out and the mine was re-opened, ten days were required for workers to remove debris and reach the bodies of those who had been trapped inside the mine. The dead consisted of 1,518 Chinese and 31 Japanese. Most of the bodies were later buried in a mass grave. After the war and liberation of China by the