CHARLESTON, W.Va. -- Massey Energy continues to argue that the Upper Big Branch Mine Disaster could not have been anticipated or prevented, despite evidence of two incidents in 2003 and 2004 that match the company's theory of the April 5 explosion that killed 29 miners.Massey CEO Don Blankenship on Tuesday touted what he called the "biggest discovery" of the company's own investigation, saying Massey experts think natural gas -- not methane -- fueled the blast.At an investors' conference in New York, Blankenship said company officials believe natural gas from a reservoir below entered the Upper Big Branch Mine through a large crack in the mine floor."It illustrates that it's something unusual, that it's more likely than not that it came out of the floor, that it didn't come out of the normal mining process, and it's not something you would normally be guarding against," Blankenship said.Natural gas is made up mostly of methane, but can contain other flammable gases, such as propane and ethane. While methane is liberated from coal seams during the mining process, natural gas can be located near mining operations in separate underground reservoirs.Massey said Tuesday that gas emissions shortly after the April 5 explosion and more recent emissions from the longwall area of the mine showed the gases involved were more likely natural gas, as opposed to methane."Most often the industry in these situations has not been focused on the possibility of natural gas," Blankenship said. "So we think it's a big discovery and they'll be a lot more of that coming out over the next few weeks as we get some material ready to prevent that more broadly."Blankenship did not mention the previous incidents in 2003 and 2004, when the Upper Big Branch Mine became inundated with gas from cracks in the mine floor. No one was injured in the previous incidents.Both times, MSHA investigators concluded the likely source for the gas was geologic reservoirs beneath Upper Big Branch, rather than methane released from the coal-bed itself.Davitt McAteer, an independent investigator appointed by the Manchin administration, noted that there has been no complete explanation thus far of what steps -- if any -- Massey took or MSHA required to try to avoid a repeat of the 2003 and 2004 incidents."If you had two of them in 2003 and 2004, why wouldn't you be guarding against it?" McAteer said. "There had been a history of these. There is sufficient science out there to tell you this phenomenon is occurring."In a follow-up statement to Blankenship's New York speech, Massey general counsel Shane Harvey tried to tie the natural gas inundation theory to the company's ongoing dispute with MSHA over testing key water spray systems on the Upper Big Branch longwall mining machine."The company hopes to further analyze cracks near the tail of the longwall that may have allowed natural gas to inundate the mine, but is currently receiving pressure from MSHA to inundate the area with water and rock dust," Harvey said. "The company is also asking MSHA for permission to bring in specialized equipment to study the area, but has received resistance from MSHA."Federal and state investigators have already found that at least four water sprays -- used to keep down explosive dust in the working section of the mine -- were missing from the longwall's cutting machine, or shearer. Government officials want Massey to resupply the machine with water so they can test the other, remaining parts of the spray system to see if they work properly.Last week, MSHA cited Massey for refusing to go along with the water spray testing plans, and the agency has hinted it might take more drastic action -- such as taking over that part of the mine or seeking a federal court injunction against Massey.The two sides had been facing a deadline of noon Tuesday for Massey to back off and assist with the testing, but MSHA agreed to give the company until Friday to comply.Reach Ken Ward Jr. at email@example.com or 304-348-1702.