REFILE-UPDATE 1-Utah mine collapse caused by faulty design-probe

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By Dan Whitcomb

LOS ANGELES, July 24 (Reuters) - A 2007 Utah coal mine collapse that killed six miners and three rescuers was triggered by a faulty mine design, federal investigators said on Thursday, rejecting the owner's claim that it was caused by an earthquake.

In announcing its findings, the Mine Safety and Health Administration fined the Crandall Canyon Mine's operator $1.6 million for a violations of its safety code. Genwal's engineering firm, Agapito Associates Inc., was fined $220,000.

Six coal miners were killed in the dramatic cave-in of the Crandall Canyon Mine in central Utah on Aug. 6, 2007 that drew worldwide media coverage as rescuers made frantic efforts from below ground and above to reach the men.

Ten days later two mine employees and a Mine Safety and Health Administration inspector died during a second collapse that forced officials to end the rescue effort and say there was no hope of finding the trapped miners alive.

Outspoken Crandall Canyon Mine owner Robert Murray said at the time that the collapse was due to an earthquake in the area, but MSHA investigators dismissed that assertion in releasing the findings at a briefing with reporters in Utah on Thursday.

"First of all it was not, and I'll repeat not, a natural occurring earthquake but in fact it was a catastrophic outburst of the coal pillars that were used to support the ground above the coal seam," MSHA chief Richard Stickler said.

Stickler said the pillars "failed under the excessive load and ejected coal very violently and filled up most of the tunnels or entries" with coal and debris.

The cave-in registered as a 3.9 magnitude seismic event and covered 50 acres (50 hectares), or an area the size of 40 American football fields, according to a report released in June by Utah seismologists.

Among the violations cited against Genwal were failing to contact MSHA after previous collapses, failing to revise its roof control plan, removing coal that had been used to support the roof and maintaining inadequate pillars.

"It was a mine design issue and the design created pillars that were simply not large enough to support the load," MSHA investigator Richard Gates said.

Rescuers who could not immediately determine if the trapped miners were alive or dead bored seven holes into the shaft in a desperate bid to find them, but were unable to establish contact before the second cave-in forced them to give up.

The Crandall Canyon Mine is on a high desert plateau some 140 miles (225 km) south of Salt Lake City, in what is known as Utah's "castle country" because of the towering rock spires that dot the rugged landscape.

(Editing by Sandra Maler)