http://www.cnn.com/2007/US/08/11/utah.mine/index.htmlMurray has insisted a magnitude-3.9 earthquake caused the mine collapse, and has said at least 10
"aftershocks" have been recorded, with seismic activity earlier wiping out more than 300 feet of progress
and halting rescue efforts temporarily.
Seismologists and geophysicists have not been as sure, saying the seismic activity they measured appeared
to stem from the mine's collapse.
University of California-Berkeley seismologist Douglas Dreger said the data show the shaking detected
bore the signature of a collapse and "not a tectonic earthquake."
Experts have said the "aftershocks" could be the rock adjusting after the collapse.
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The rest of the article ..... Workers were worried about the dangers in the mine
earlier ...... Workers report of fear of being fired if you reported a safety issue ........
mine had been fined before ..... the floor of the mine shaft were the collapse happened
was buckled by the pressure ....