Huntington, Utah Some noise was detected by two devices monitoring vibrations near where six miners were trapped by a cave-in nearly 10 days ago, raising "a very small amount" of hope that the men might be found alive, officials said.
The sound picked up by two geophones could be a rock breaking underground, or even an animal, said Richard Stickler, chief of the federal Mine Safety and Health Administration.
"We saw some indication of noise for a period of about five minutes that we had not seen before," Stickler said.
While the source of the noise wasn't known, Stickler said it had "created a very small amount of hope and optimism" among the families.
Rescuers were in the process of dropping a video camera and microphone down more than 1,800 feet through narrow holes drilled into the mine, he said. Plans for a fourth borehole had changed because of the "unusual" readings.
Said Bob Murray, chief of Murray Energy Corp., the co-owner and operator of the Crandall Canyon Mine: "Don't read too much into this noise we picked up, but it is a sign of hope."
Still, experts say the chances of finding the men alive are slim.
As crews slowly dig a path to the men's presumed location at the Crandall Canyon Mine, the narrow drill holes sunk deep into the mountain amount to little more than educated guesses.
"There are a lot of possibilities," Stickler said. "We started with logical thinking: 'If I were in this situation, what would I do?' That has guided us in where we look."
The men could be huddled together or spread out anywhere in an underground area the size of several football fields.
"There's always a chance. You have to hang on to that chance. But realistically it is small, quite small," said J. Davitt McAteer, former head of the MSHA and now vice president of Wheeling Jesuit University in West Virginia. "You would have to have every single break and divine intervention to successfully extract these guys."
The Aug. 6 cave-in released low-oxygen air from sealed chambers into the working area of the mine. Downward pressure on the walls sent chunks of coal flying like bullets through the shaft.
Two holes drilled into the mine have not located the men. A third drill broke through Wednesday into an area where officials say the men may have sought refuge, but a microphone snagged in the hole about 20 feet above the roof of the mine, and it couldn't pick up any sound that might have come from below. Officials planned to lower a video camera with its own microphone in the next attempt.
"We're going to keep drilling until we find these miners," Murray said Wednesday.
Murray has acknowledged the drilling may not show whether the miners are alive or dead. At nearly every turn, he cautions reporters that the initial blast inside the mountain may have killed the men instantly.
Mining rescues after 10 or more days are not unheard of. In May 2006, two miners were rescued after being trapped for 14 days following a collapse at an Australian mine. In 1968, six miners were rescued after 10 days in West Virginia.
"I am still very optimistic that we will find these miners alive. There is real reason to believe that," Murray said Wednesday. "I still remain very, very hopeful."