Structure damage may be best evidence of an explosion. Molten metal may be deposited by gravity, air flow, blast wave, or relative motion or a combination of the foregoing. Gas released from pressurized containers may given strange burn patterns. Nitrogen will tend to suppress the fire and high pressure air may give evidence similar to oxygen. Oxygen release may result in severe burning often resulting in a white ash deposit.
Fire can spread by radiation, convection, and conduction heat transfer.
Make a matrix. A breaking spar can sound like an explosion. Important to identify location, color, intensity, and time of emissions. Location of witness and environmental background. If time factors are questionable, request simulation or rerun, if possible.