Explosion. Airborne detonation test of an industrial mining explosive. Instruments around the fireball measure its thermal output. Explosives burn rapidly, creating large amounts of gas & heat to cause a sudden increase in pressure. Explosives need to be studied carefully to allow them to be stored and used safely. Photograph of five kilogrammes of explosive being detonated during research conducted by the Health and Safety Laboratory, Britain. CROWN COPYRIGHT UNDER LICENCE FROM THE HEALTH & SAFETY LABORATORY & CONTROLLER OF HER MAJESTY'S STATIONERY OFFICE