'Quakes' hit mining areas, affect search

Almost a day after a devastating 3.9 magnitude seismic event trapped six miners inside the Crandall Canyon Mine, another event measuring 1.0 on the Richter scale was recorded near the Aberdeen Mine — more than 30 miles away.

The minor seismic event, about six miles northeast of Helper, was recorded at 2:31 a.m. Tuesday. Seismologists believe it is consistent with mining operations in Utah's coal country.

"We see these events on a daily basis," said Relu Berlacu at the University of Utah Seismograph Stations. "If you look at the distribution of earthquakes in the area, you'll see this tendency of clustering around where the mines are. Most of them are generated by the mining itself."

A check of recent earthquakes recorded in the area shows a cluster of small quakes around the mines. Seismologists say some of them may be natural earthquakes, but many of them are a result of mining.

"That area is known as the coal mining seismic belt," said Dave Tabet, the energy and minerals program director for the Utah Geological Survey. "The way they're mining, they're always setting off seismic events."

Other scientists agreed.

The seismic waves in the area of the mine were similar to those caused by a collapse and not an earthquake, said Rafael Abreu, a geologist with the U.S. Geological Survey's National Earthquake Information Center in Golden, Colo.

"What we seem to see from the data we're looking at, we're seeing a mine collapse," he told the Deseret Morning News.

He based that on reading of the seismic waves, as well as a review of the geological area. While the conclusion is not final, Abreu said the initial seismic event and the "after events" were likely caused by the mine collapse.

Rescuers trying to reach the trapped miners are having to deal with seismic problems inside the Crandall Canyon Mine.

"There has been seismic activity," Assistant Labor Secretary Richard Strickler said. "Bumps, movements of the mountain. This puts a safety hazard to the rescue workers."

A pressure-shifting "bump" inside a mine shaft forced rescuers to leave the mine early Tuesday. At 2:43 a.m. Tuesday, a 1.6 magnitude event was registered in the same general area as the one that trapped the miners. Others ranging from 1.2 to 2.2 on the Richter scale were recorded in the general area Monday night and early Tuesday.