HUNTINGTON, Utah – Seismic activity has “totally shut down” efforts to reach six miners trapped below ground and has wiped out all the work done in the past day, a mine executive said Tuesday.

“We are back to square one underground,” said Robert E. Murray, chairman of Murray Energy Corp., owner of the Crandall Canyon mine.

Still, “we should know within 48 to 72 hours the status of those trapped miners,” Murray said. Crews are drilling two holes into the mountain in an effort to communicate with the miners – provided they are still alive.

Unstable conditions below ground have thwarted rescuers’ efforts to break through to the miners, who have been trapped 1,500 feet below the surface for nearly two days, Murray said.

The seismic activity and other factors “have totally shut down our rescue efforts underground,” he said.

Rescuers were able to get within 1,700 feet Monday but had advanced only 310 feet more since then, Murray said earlier Tuesday. The seismic shocks caused cave-ins that blocked even that progress, he said.

Rescue teams will be ready to start over again Wednesday afternoon at the earliest, Murray said.

“There is absolutely no way that through our underground rescue effort we can reach the vicinity of the trapped miners for at least one week,” Murray said.

The National Earthquake Information Center in Colorado said 10 seismic shocks have been recorded since the collapse, but only one since 3 a.m. Tuesday. That one struck at 3:42 p.m. with a magnitude of 1.7.

Murray has insisted the cave-in was caused by an earthquake. But government seismologists have said the pattern of ground-shaking picked up by their instruments around the time of the accident Monday appeared to have been caused not by an earthquake, but by the cave-in itself.

“Based on the information and preliminary analysis we’ve done so far, this event doesn’t look like a natural event. It doesn’t have the proper characteristics of a natural earthquake,” said Rafael Abreu, a geologist for the earthquake information center. “Even though it’s not a natural earthquake, it could still generate aftershocks, which is exactly what we’re seeing in this particular situation.”

Murray lashed out at the news media for suggesting his men were conducting “retreat mining,” a method in which miners pull down the last standing pillars of coal and let the roof fall in.

“This was caused by an earthquake, not something that Murray Energy … did or our employees did or our management did,” he said, his voice often rising in anger. “It was a natural disaster. An earthquake. And I’m going to prove it to you.”

Amy Louviere, a spokeswoman for the federal Mine Safety and Health Administration in Washington, said the men at the mine were, in fact, conducting retreat mining.

However, Louviere said that exactly what the miners were doing, and whether that led to the collapse, can be answered only after a full investigation.

Retreat mining has been blamed for 13 deaths since 2000, and the government requires mining companies to submit a roof control plan before beginning such mining. Such a plan details how and when the pillars will be cut and in what order.

The mine had submitted such a plan and received approval in 2006, Louviere said.

“As long as they abide by that plan, it can be a very safe form of mining,” she said. “What we’ve found with recent fatalities that the operator was found to not be following the roof control plan.”

More than a day and a half after the cave-in, rescuers were unable to say whether the men were dead or alive, and had not even heard any pounding from their hammers, as miners are trained to do when they get trapped.

“The Lord has already decided whether they’re alive or dead,” Murray said. “But it’s up to Bob Murray and my management to get access to them as quickly as we can.”

The trapped miners were believed to be about 3« miles inside the mine, situated 140 miles south of Salt Lake City.

Two holes were being drilled vertically in an attempt to get air and food to the miners and to communicate with them, said Richard Stickler, head of the MSHA, at a news conference.

If the men were not killed by the cave-in itself, Murray said, he believed there was enough air and water for them to survive for days or “for perhaps weeks.” But the government’s chief mine inspector in the West was not as confident.

“We’re hoping there’s air down there. We have no way of knowing that,” said MSHA’s Al Davis.

There were 30 pieces of heavy mining equipment in place and 134 people dedicated to the rescue, Murray said. Two C-130s from the Air Reserve in Pittsburgh were being sent with seismic equipment and staff.

Before the work was stopped Tuesday, mine shafts were being reinforced with timber and steel beams, and ventilation systems were being repaired, Stickler said.

Stickler would not comment on whether retreat mining caused the collapse but said the practice has been used there to extract coal.

After meeting privately with family members of the miners, Murray outlined plans to bulldoze a mountain path and erect a seismic listening device outside the mine that could reveal whether any men were alive.

He said that once the device was in place, crews would set off dynamite, a sign to miners to tap the ceiling with hammers.

Four miners escaped, but they were not in the same area as their trapped brethren, according to Murray.

During a rambling and often angry news conference, Murray lashed out at The Associated Press and Fox News for suggesting the men were retreat mining at the time.

“The damage in the mine was totally unrelated to any retreat mining,” Murray said. “The pillars were not being removed here at the time of the accident. There are eight solid pillars around where the men are right now.”

On Monday, seismograph stations recorded seismic waves of 3.9 magnitude, and authorities briefly thought the ground shaking was an earthquake.

Murray Energy insisted the cave-in was caused by an earthquake, saying the ground shaking was in a spot 3,500 feet deeper than where the miners were. The company also claimed the shaking lasted four minutes.

But the University of Utah Seismograph Stations and Jim Dewey of the U.S. Geological Survey in Denver said it appeared the trembling was caused by the cave-in.

Mine collapses have a seismic signature distinct from earthquakes because they tend to occur at shallower depths and at different frequencies.

The first motions of the Utah disturbance indicated a downward movement consistent with a collapse, scientists said. If it had been an earthquake, it would have produced up and down motions on the seismograms, they said.

Little was known about the six miners; only one has been identified. The Mexican Consulate in Salt Lake City said three of the men are Mexican citizens.

In Huntington, 10 miles from the mine, residents were anxious for news, and the strain could be seen in their somber looks. The families of the trapped miners were sequestered at a junior high school in Huntington, about six miles from the mine, and police stood guard on the grounds.

LaRena Collards, 71, was making cakes for families of the trapped miners, just as she did in 1984 when a fire killed 27 people at another mine.

“You just ask the Lord to bless the families and give them the strength to get through this,” Collards said.