Crandall Canyon Coal Mine Collapse
I had my suspicions about this one from the first day of reporting, which I guess was last Monday. That would have been the day of our convocation at VSU, where I am now teaching on a one-year temporary appointment.
Geophysicists with both the University of Utah and the U.S. Geological Survey were already saying late Monday that the event recorded on seismographs was the collapse itself, rather than an earthquake which triggered it. I know of a similar collapse event which is often mistaken for an earthquake in the seismological record for the anthracite coal fields of Pennsylvania. A "first motion" or "moment tensor" analysis using seismographs from throughout the western United States has now been completed by a team at the Berkeley Seismological Laboratory. The source mechanism for the August 6 seismic event is most consistent with the collapse of an underground cavity.
Robert Murray, who owns part of the mine in which the six miners are now entombed, continues to question the findings of geophysicists which have been reported by the press. For an excellent analysis of the mining methods and rock properties that played a role in this disaster see the recent post at The Oil Drum.