🔹 1. Introduction

Avalanche blasting is a controlled-release blasting method used to prevent dangerous snow or rock avalanches on steep mountain slopes.It uses small explosive charges placed strategically to break up unstable snow layers before they slide naturally.
This is a vital practice for safety near mines, highways, and hydropower projects located in hilly regions.

🔹 2. Purpose of Avalanche Blasting

• To stabilize snow slopes by releasing small avalanches safely.
  
• To prevent large natural avalanches threatening mining sites or transport routes.
  
• To ensure worker safety in open-cast mines near hilly zones.
  

🔹 3. Explosives Used

Type	Example	Use
High explosives	Gelignite, Emulsion, ANFO	Main charge
Detonating cord	PETN cord	Transmission line
Initiator	Nonelectric detonator (Nonel)	Safe initiation
Primer	Cast or gelatin cartridge	Boost initiation

🔹 4. Initiation Systems

• Nonel (Nonelectric) System: Shock tube carries signal via gas impulse, not current. Immune to static electricity.
  
• Detonating Cord System: PETN cord detonates sequentially along the slope.
  
• Electronic Delay System: Provides precise timing between multiple shots.
  

🔹 5. Blasting Procedure

1. Evaluate snowpack stability and weather.
   
2. Select blasting points at tension zones.
   
3. Fix charges (2 – 5 kg equivalent TNT).
   
4. Connect detonators in sequence.
   
5. Move to safe distance and fire using remote or long fuse.
   
6. Record blast data and check post-blast safety.
   

🔹 6. Safety Precautions

• Maintain minimum 300 m safety radius.
  
• Never use electric detonators during snowstorms (static danger).
  
• All persons must shelter behind natural cover.
  
• Keep first-aid & communication ready.
  

🧠  25 Objective Questions (DGMS Pattern)

1. Avalanche blasting is primarily performed to — 

a) Break rock for tunnelling
b) Stabilize snow and release small avalanches safely
c) Clear vegetation from slopes
d) Test explosives at high altitude
e) Create firebreaks
Answer: b) Stabilize snow and release small avalanches safely
Solution: Avalanche blasting's objective is controlled snow release to prevent larger, dangerous avalanches.

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2. Which initiation system is preferred in avalanche blasting because it resists static ignition? 

a) Electric instantaneous caps
b) Cap-and-fuse only
c) Nonel (nonelectric shock tube)
d) EBW with long wires
e) Cord-and-delay caps
Answer: c) Nonel (nonelectric shock tube)
Solution: Nonel transmits a shock wave and is immune to stray currents and most static electricity hazards.

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3. EBW (Exploding Bridgewire) detonators are characterized by — 

a) Being easily triggered by static electricity
b) Containing large amounts of primary explosive
c) Requiring a precise high-energy electrical pulse to fire
d) Being the same as electric caps
e) Always used with safety fuses
Answer: c) Requiring a precise high-energy electrical pulse to fire
Solution: EBW detonators contain no primary explosive and need a precise high-energy pulse, making them immune to stray currents.

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4. A standard avalanche charge is chosen to produce a detonation pressure equal to — 

a) 0.1 kg TNT equivalent
b) 1 kg TNT equivalent
c) 5 kg TNT equivalent
d) 10 kg TNT equivalent
e) 50 kg TNT equivalent
Answer: b) 1 kg TNT equivalent
Solution: Avalanche blasting commonly uses charges sized to about 1 kg TNT equivalent for controlled effect.

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5. In severe winter weather with high static fields, which is the least safe to use? 

a) Nonel tube
b) EBW detonator system
c) Cap-and-fuse assembly with ordinary cap
d) Detonating cord initiated from a safe shelter
e) Remote electric firing with shielding
Answer: c) Cap-and-fuse assembly with ordinary cap
Solution: Cap-and-fuse assemblies (especially with small caps) are more susceptible to accidental ignition from static electricity.

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6. Before using a newly purchased roll of safety fuse, the blaster should — 

a) Cut it into short lengths immediately
b) Test a segment to determine the burning rate
c) Use it straight away without testing
d) Freeze it to improve burning consistency
e) Paint it for visibility
Answer: b) Test a segment to determine the burning rate
Solution: Always time a test segment to know burn rate and ensure a safe margin; never cut to less than minimum allowed burn time.

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7. Minimum allowable burning time for a safety fuse (general guideline) should not be less than —

a) 30 seconds
b) 60 seconds
c) 120 seconds
d) 300 seconds
e) 10 seconds
Answer: c) 120 seconds
Solution: The manual states fuse lengths should allow at least 120 seconds burning time (or as required by local law) for safety.

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8. When should an explosive charge be armed during avalanche blasting operations? 

a) As soon as it is taken from the magazine
b) In advance at the base camp for speed
c) As late as possible — ideally just before tossing/placing
d) Immediately after drilling the borehole
e) At the start of the day before moving out
Answer: c) As late as possible — ideally just before tossing/placing
Solution: Delay arming to minimize exposure to accidental initiation; arm only when ready to place/fire.

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9. Which primer type may freeze and become dangerously sensitive when frozen (around −29°C)? 

a) PETN cord
b) Gelatin primer (nitroglycerin-based)
c) Cast TNT primer
d) Emulsion tubes
e) Water gel explosives
Answer: b) Gelatin primer (nitroglycerin-based)
Solution: Gelatin (nitroglycerin-containing) primers freeze around −29°C and can be unstable if thawed improperly.

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10. In cornice blasting, using boreholes rather than surface charges typically results in — 

a) Increased amount of explosive required
b) Less efficiency and more scatter
c) Roughly half the explosive required for the same effect
d) Greater risk so it is avoided
e) No difference in explosive quantities
Answer: c) Roughly half the explosive required for the same effect
Solution: Borehole cornice blasting is more efficient and often uses about half the explosive compared to surface charges.

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11. Which device is used to project explosive projectiles for remote avalanche control? 

a) Avalauncher
b) Howitzer 105 mm only
c) Overland pipe conveyor
d) Sprag clutch device
e) Detonating cord launcher
Answer: a) Avalauncher
Solution: Avalaunchers are pneumatic devices designed to fire projectiles that carry charges to remote slopes for avalanche control.

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12. When using an avalauncher, the standard test fire pressure often referenced is about — 

a) 10 psi
b) 25 psi
c) 50 psi
d) 200 psi
e) 1000 psi
Answer: c) 50 psi
Solution: Procedures recommend test-firing an unloaded avalauncher at around 50 psi to check for clear barrel and function.

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13. Which of the following is a safe practice for carrying hand charges during avalanche work? 

a) Keeping igniters installed in all charges for quick use
b) Carrying multiple armed charges in one pack for speed
c) Carrying charges unarmed and ignitors separately; arm only at the shot point
d) Storing charges loose in pockets for quick access
e) Arming charges at base camp before skiing out
Answer: c) Carrying charges unarmed and ignitors separately; arm only at the shot point
Solution: Explosives should be carried unarmed; ignitors kept separate and attached only when ready to fire.

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14. After a misfire, the blasting crew should normally wait at least — 

a) 5 minutes
b) 15 minutes
c) 1 hour
d) 24 hours always
e) No waiting is necessary if it looks safe
Answer: c) 1 hour
Solution: The guide advises waiting at least one hour (some regs may specify longer) before approaching a misfire.

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15. In avalanche blasting, detonating cord should be used at a minimum loading of —

a) 5 grains/ft

b) 10 grains/ft
c) 25 grains/ft
d) 50 grains/ft
e) 100 grains/ft
Answer: c) 25 grains/ft
Solution: A minimum of 25 grains per foot of detonating cord is recommended for reliable initiation of charges.

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16. Which statement about two-component explosives (mixed in the field) is TRUE? 

a) They are high explosives while stored separately and remain so
b) They are non-explosive even after mixing
c) Stored separately they are not high explosives; they become high explosives when mixed
d) They are safer than any single-component explosives in all conditions
e) They can be reliably used at very low temperatures without mixing time
Answer: c) Stored separately they are not high explosives; they become high explosives when mixed
Solution: Two-component systems avoid high-explosive storage classification until mixed; mixing requires time and temperature control.

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17. For borehole cornice blasting, the driller should normally bore holes to a depth of — 

a) Full thickness of the cornice
b) Slightly more than full thickness of cornice
c) No deeper than half the thickness of the roof/cornice
d) More than twice the cornice thickness
e) Exactly one quarter of the cornice depth
Answer: c) No deeper than half the thickness of the roof/cornice
Solution: Recommended borehole depth is usually not more than half the cornice thickness to reduce exposure and ensure effectiveness.

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18. Which detonator system is least likely to be accidentally initiated by radio frequency transmissions? 

a) Electric blasting caps with direct wires
b) Nonel shock tube with nonelectric caps
c) EBW detonators (with special firing set)
d) Simple safety fuse with cap
e) Wireless remote detonators
Answer: c) EBW detonators (with special firing set)
Solution: EBW systems require a precise high-energy pulse and contain no primary explosive; they are not detonated by stray RF.

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19. When using cap-and-fuse in avalanche zones, a recommended safety practice is to — 

a) carry caps inserted in fuses the whole trip for speed
b) cut fuse ends on arrival to the blasting point and insert cap immediately before throwing/placing the charge
c) pre-install ignitors at base camp and leave them on for the day
d) use shorter-than-legal fuse lengths to speed escape
e) spray fuses so they burn faster
Answer: b) cut fuse ends on arrival to the blasting point and insert cap immediately before throwing/placing the charge
Solution: Fuse should be prepared and the cap inserted only at the final arming step, then fired immediately.

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20. Which factor most increases the risk of accidental initiation in avalanche blasting operations? 

a) Cold temperatures alone
b) High static electricity fields (e.g., cumulonimbus)
c) Bright sunshine
d) Clear skies and low humidity
e) Using detonating cord properly
Answer: b) High static electricity fields (e.g., cumulonimbus)
Solution: Strong static fields are specifically noted as increasing accidental initiation risk for cap-and-fuse systems.

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21. When a charge must be tossed onto a hard snow surface, it should be — 

a) thrown without concern
b) belayed or anchored to prevent sliding off target
c) arm and left to slide where it goes
d) wrapped in cloth and left unattended
e) ignited in hand before throwing
Answer: b) belayed or anchored to prevent sliding off target
Solution: Charges that might slide must be belayed/anchored to ensure they remain at the intended detonation point.

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22. Which of the following is a correct action after firing avalanche charges? 

a) Immediately rush down slope to inspect results
b) Wait for a safe confirmation and then check for misfires; record shot data
c) Assume all worked and no checks needed
d) Remove any partially exploded charges by hand immediately
e) Leave area without recording details
Answer: b) Wait for a safe confirmation and then check for misfires; record shot data
Solution: Post-blast checks, misfire procedures, and recording shot data are mandatory safety/administrative steps.

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23. The typical role of a blaster-in-charge in avalanche operations includes — 

a) Only carrying explosives without planning
b) Supervising all phases, deciding safe working lines, and ensuring team training
c) Letting untrained helpers place charges for speed
d) Using improvised initiation methods to save time
e) Handling ammunition disposal alone without reporting
Answer: b) Supervising all phases, deciding safe working lines, and ensuring team training
Solution: The blaster-in-charge is responsible for overall planning, safety, and supervision of the blasting team.

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24. Which of the following is TRUE about misfires in avalanche blasting? 

a) They can be approached immediately with no waiting
b) They must be reported and carefully investigated; do not attempt risky retrievals; wait per regulation before approach
c) They should always be detonated by lighting surrounding snow on fire
d) Misfired charges are safe and require no action
e) Misfires are always caused by operator error only
Answer: b) They must be reported and carefully investigated; do not attempt risky retrievals; wait per regulation before approach
Solution: Misfires require careful handling, reporting, waiting periods, and structured disposal procedures.

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25. Which weapon system is mentioned as adapted for avalanche control (used to fire explosive rounds into slopes)? 

a) 30 mm autocannon
b) 105 mm howitzer / avalauncher (adapted systems)
c) Russian Katyusha rockets
d) Shoulder-fired rockets (RPG)
e) Hand-thrown grenades
Answer: b) 105 mm howitzer / avalauncher (adapted systems)
Solution: The manual references howitzers and avalaunchers adapted for avalanche control and explains their procedures and safety needs.

                                🔚 8. Conclusion

Avalanche blasting is a preventive measure rather than a destructive one.

The Nonel system’s immunity to static and electrical hazards makes it the safest choice in snowy regions. DGMS emphasizes strict adherence to weather, safety, and explosive-handling protocols.

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