Vibration of the atmosphere due to the release of explosives energy.

The three main sources of airblast are rock release pulse, stemming release pulse and rock piston effect.

1. Rock release is where the face bursts due to inadequate burden.
2. Stemming release is due to rifling or cratering of the blast hole collar.
3. Rock piston is the large, low frequency, movement of air driven by the movement and swelling of the blasted rock mass.