50 years ago tomorrow.

The bump spread as three distinct shock waves, resembling a small earthquake throughout the region, alerting residents on the surface for a wide area to the disaster. Draeger teams and teams of barefaced miners entered the No. 2 colliery to begin the rescue effort. The rescue teams encountered survivors at the 13,400 foot level walking or limping toward the surface. Gas released by the bump was encountered in increasing concentrations at the 13,800 foot level where the ceiling had collapsed and rescuers were forced to work down shafts that were in partial state of collapse or were blocked completely by debris.


http://en.wikipedia.org/wiki/Springhill_Mining_Disaster