Abstract: A seismic explorative system for wilderness areas is described having a nonincendiary high core load linear detonating cord as the seismic energy source. The cord rests on the earth's surface in essentially an uncovered condition and comprises an elongated core of detonating explosive having a core load of about 100-400 grains per foot, an encircling layer consisting essentially of flame quenching particulate material adjacent the core along its entire length, a textile covering circumscribably confining both the core and the encircling layer and a fire retardant outer sheath protectively enclosing the textile covering.