The Bureau of Mines developed methods for fragmenting oil shale formation with chemical explosives to prepare oil shale for in situ retorting and evaluating the extent of fragmentation by various methods. A combination of three methods of explosive fracturing was used: (1) The displacement and detonation of a liquid chemical explosive in a natural fracture (2) the use of 60-per dynamite to relieve stress conditions of the rock around the wellbore, and (3) the use of pelletized TNT in a series of wellbore shots to fragment the oil shale. Seven methods were used to evaluate the fragmented zone. A seismic method was used to delineate the fragmented zone with results base on arrival time, amplitude and record quality. The data from the seismic measurements indicated the extensively fragmented zone was approximately 95 ft. in diameter and 70 ft. thick. Results of the remaining methods of evaluating fractures--including airflow tests, coring of the expected fragmented zone, elevation measurements to indicate overburden crowning, and surveys with high speed camera, impression packer, and down-hole camera--agreed with and supported the data from seismic measurements.