Which of the following is a recognized factor contributing to fly rock?

• A. Angled holes
• B. Using properly aligned holes
• C. Excessively long delays between shots
• D. Placing charges far from the blast area

Answer: (C)

Fly rock happens when rock fragments are projected beyond the blast area. Timing plays a big role in how energy is released and how rock breaks and moves. If delays between shots are excessively long, the energy from different holes isn’t released in a coordinated, contained way. The first blasts create fractures and loosened pieces, and when the later detonation finally occurs, those fragments can be accelerated outward with less confinement. The lack of synchronization allows rock to be propelled in unpredictable directions, increasing the chance of fly rock.

Other factors like angling the holes or ensuring proper alignment mainly affect the direction and confinement of energy, while placing charges farther from the blast area naturally reduces risk. But the specific timing issue—very long delays between shots—is a recognized factor that can contribute to fly rock.