AN UNKNOWN QUANTITY OF MATERIAL UNRAVELED FROM THE BACK OF THE S200 DRIFT ON 3870 LEVEL. THE FAILURE STARTED IN A FRESH BLASTED ROUND. THE CAVE PROGRESSED TOWARDS THE 3870 ACCESS/100-S200 INTE RSECTIONS & FINALLY CHOKED ITSELF OFF AFTER DAMAGING THE EXISTING SUPPORT. 08/02/02 IS WHEN IT AFFECTED THE GROUND SUPPORT. CALLED MSHA ON 08/02/02.