Mochia mine, in culmination of depillaring operations, fired India's
largest underground pillar blast consuming 145 tonnes of explosive and
yielding 0.55 million tonnes of ore in June 1994. To protect main mine
structures (situated at a distance of 250 to 350 m from the blast site) from
resultant ground vibrations, the charge per delay was restricted to
2300 kg. The post-blast observations revealed that no damage was caused
to these structures. However, the damage assessment survey of the mine
workings situated in close proximity revealed a general trend in
consonance with the distance from the blast and found to be well
correlated with peak particle velocity.