PRECURSOR SHOCKS PRODUCED BY A LARGE YIELD CHEMICAL EXPLOSION
SUFFIELD EXPERIMENTAL STATION RALSTON (ALBERTA)
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In July 1964, a 500 ton TNT hemispherical surface burst charge was detonated at Suffield Experimental Station. High-speed photographs of the explosion show that in some radial directions dust clouds moved out ahead of the main shock and had reached a height of 50 ft. before its arrival. The dust clouds were enveloped by a shock wave. At ground-level this precursor eventually became downward facing and produced a reflected shock and a Mach stem. Photography from an aeroplane at 19,000 ft. immediately above the explosion showed that all the precursors were produced along well-compacted roadways running radially from the charge centre. A gauge measuring the total density within the blast wave, showed the dust density to be four times that of the peak air density expected in the blast wave at that position. Targets placed in the regions of the precursors experienced considerably more damage than had been expected. From the evidence of seismometer records it seems probable that the precursors were produced by strong ground waves feeding energy into the air ahead of the air shock.