Efforts to dig out two miners buried for nearly two days beneath at least 45 feet (13.7 meters) of rocks in an open pit coal mine in Maryland resumed after a seven-hour safety delay.
Bob Cornett, acting district manager for the Mine Safety and Health Administration, said excavation was halted overnight so a crew could detonate explosives to bring down material that had threatened to fall into the work site from a 150-foot-high (45.7 meters) wall in Tri-Star Mining Inc.'s Job No. 3 mine.
He said the miners' chances of survival diminished with each passing hour.
The two were trapped Tuesday morning when the bottom of the high wall collapsed, burying them and the equipment they were operating, Cornett said. Trucks have been hauling about 2,500 tons (2,268 metric tons) of debris each hour from the pile at the western Maryland mine since then to try to reach them.
The collapse created a layer of rocks ranging from 45 feet to 100 feet (13.7 meters to 30.5 meters) deep, but rescuers believe the collapse pushed the men and their equipment toward the shallower end.
The miners were working at the bottom of the pit when the wall collapsed. Both have two-way radios, although the men have not communicated with anyone since the collapse.
Cornett said he did not believe the machines were equipped with emergency breathing apparatus. The so-called "self-contained self-rescuers" provide an hour of oxygen.
The cause of the collapse was not known, but Cornett said that rain tends to cause more high wall failures at this time of year.
The mine has had no fatal injuries since at least 1995 and was not cited for violations in its most recent inspection, which began March 5, according to MSHA. The mine employed 51 people at the end of 2006 and produced nearly 653,000 tons (592,392 metric tons) of coal last year.
Owner George R. Beener was at the site, according to a woman who answered the phone at a mine office. She said the company had no comment and declined to identify herself.