Huntington, Utah ? Seismic activity “totally shut down” efforts to reach six miners trapped below ground, causing a cave-in that 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 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 are waiting for the seismic activity to subside before going back in, Murray said. Crews are getting their supplies back in order and will be ready to start over again this afternoon at the earliest, he 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.

Rafael Abreu, a geologist for the earthquake information center, said the event didn’t look like a natural earthquake, but it could still create aftershocks.