The search for six missing miners moved toward the back of a mine yesterday, where officials hoped the men sought refuge in search of an air pocket.
Crews already have drilled two holes and fitted a camera down one of them, but they have yet to learn the coal miners' fate, eight days after the mine partly collapsed under the weight of a shifting mountain.
The camera's ghostly images revealed only one indication of a miner's presence: a tool bag for hammers, wrenches and chisels hanging from a post, 5.5km from the entrance and more than 550m underground.
"It indicates we're very close to where the miners were working," said Bob Murray, chief of Murray Energy Corp, co-owner and operator of the Crandall Canyon mine.
The collapse of the mine's midsection was thought to have pushed ventilated air into a pocket at the rear of the mine, where the miners may have fled when their escape routes were cut off by rubble, said Richard Stickler, chief of the US Mine Safety and Health Administration (MSHA).
The thunderous collapse blew out the walls of mine shafts but left reinforced ceilings mostly intact.
"We see a lot of open area. We see good height. Space is what they need and we saw a lot of space," said Al Davis, who heads up MSHA's Western operations.
Other video images taken on Sunday showed a twisted conveyer belt, pipes and dripping water.
As crews started drilling a camera hole late on Monday, Murray said the pace of rescue efforts picked up inside the mine, where heavy machinery was clawing at loose rubble that nearly fills a main passageway.
Rescuers cleared about 207m of the 610m of rubble they were expected to encounter in the mine's main passageway. The effort could take several more days, but for the first time since the Aug. 6 collapse, the rescuers were progressing steadily forward.
Mining rescues after eight or more days are not unheard of. In May last year, two miners were rescued after being trapped for 14 days following a collapse at an Australian mine.