July 18, 2011
Saturday's small earthquake was not caused by and did not affect mining operations at Twentymile Mine, according to mine owner Peabody Energy and the federal agency that overseas mine safety.
Stories this photo appears in:
Mild temblor detected 12 miles southwest of Steamboat
The last time the U.S. Geological Survey reported a small earthquake in the vicinity of Twentymile Mine on March 30, the cause of the seismic activity proved to be the settling of a column of coal supporting the ceiling of a mine shaft. That was not the case this time, according to mine owner Peabody Energy.