Fourth bore drilled in search for miners |

Fourth bore drilled in search for miners

HUNTINGTON, Utah – Rescuers searching for six coal miners trapped for 10 days were drilling yet another hole into mine Thursday, this time aiming for a spot where they had detected mysterious vibrations in the mountain.Officials said Thursday that the latest of three holes previously drilled reached an intact chamber with potentially breathable air.Video images were obscured by water running down that bore hole, but officials said they could see beyond it to an undamaged chamber in the rear of the mine. It yielded no sign the miners had been there.The drill holes can be used to pump air and send food down the mine, but the rescue effort is taking place underground, where miners have advanced to only 826 feet in nine days. They still have 1,200 feet to go to reach the area where the men were working.The digging was most recently set back Wednesday night, when a coal excavating machine was half buried by rubble by seismic shaking. Another so-called “mountain bump” interrupted work briefly Thursday morning.”The seismic activity underground has just been relentless. The mountain is still alive, the mountain is still moving and we cannot endanger the rescue workers as we drive toward these trapped miners,” Bob Murray, chief of Murray Energy Corp., the co-owner and operator of the Crandall Canyon Mine, said Thursday.Murray has become more reticent to predict when the excavation would be complete. At the current rate, it figures to take several more days.Murray said it would take at least two days for the latest drill to reach its target, in an area where a seismic listening device detected a “noise” or vibration in 1.5-second increments and lasting for five minutes.Officials say it’s impossible to know what caused the vibrations and on Thursday clarified the limits of the technology.The device, called a geophone, can pinpoint the direction of the source of the disturbance, but it can’t tell whether it came from within the mine, the layers of rock above the mine or from the mountain’s surface, said Richard Stickler, chief of the federal Mine Safety and Health Administration.The “noise,” a term he used a day before, wasn’t anything officials could hear, Stickler said. “Really, it’s not sounds but vibrations.”Officials stressed that the motion picked up by the geophones could be unrelated to the mine, even as they drilled the new hole in an effort to uncover the source of it.Together with the discovery of an intact chamber and breathable oxygen levels, the baffling vibrations offered only a glimmer of hope for rescuing the miners, but Murray seized on the developments Thursday.”The air is there, the water is there – everything is there to sustain them indefinitely until we get to them,” he said.Officials said results of air quality samples taken from the intact chamber, accessed by the third deep borehole, showed oxygen levels of roughly 15 to 16 percent.Normal oxygen levels are 21 percent, and readings in other parts of the mine taken since the Aug. 6 collapse have registered levels as low as 7 percent.At 15 percent oxygen, a person would experience effects such as elevated heart and breathing rates, Stickler said.Video images from the same shaft showed an undamaged section complete with a ventilation curtain that divides intake air from exhaust air. Behind the curtain, in theory, the men might have found refuge and breathable air when the mine collapsed 10 days ago.Also Thursday, Murray corrected comments he made late Wednesday that a camera that detected the curtain had been lowered through the third borehole, made at the rear of the mine. The curtain was actually observed by a camera sent down a borehole drilled earlier into an area where the trapped men had been working, he said.Nothing had been detected or heard since the five-minute period Wednesday, Stickler said Thursday.—Associated Press writers Chris Kahn and Alicia A. Caldwell in Huntington, Ed White in Salt Lake City, and Jennifer Talhelm in Washington, D.C., contributed to this report.

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