Manual release of avalanches
The release of avalanches by hand is still the most frequently used method in the Alps , alongside avalanche release by helicopter . The particular advantage of triggering an avalanche by hand is that the avalanche starting zone can be selected individually and according to the respective situation and the success of the blast can thus be optimized.
procedure
commitment
However, it can only be used if visibility is good, if there is safe access to the place of use and if there is also an escape route. A special permit is required in Austria and Switzerland for the use of explosives to trigger an avalanche. Due to the diverse training and education, accidents and deaths when avalanches are detonated by explosives are very rare.
The individual charge per blast is usually around 1 to 2.5 kg. The explosive charge must be secured with a rope in order to be able to recover possible failures from the avalanche slope. So that the explosives thrown by hand cannot slide down the slope in an uncontrolled manner before it ignites, the cartridges are pierced crosswise with two wooden skewers so that the explosive remains on the sloping surface of the snow (see video below).
When throwing the explosive charge by hand, it is not prescribed in every country that two detonators and two fuses are used, but this is recommended (redundant detonation).
The safety distance from the detonation site must be at least 50 meters; in any case, sufficient safety distance must be maintained so that no person is in the area where the avalanche is released or the area where the detonation acts as a result of scatter and pressure.
For the trigger point height, explosives and the amount of explosives as well as the ignition of the explosives, see: Avalanche triggering by explosives and artificial avalanche triggering .
The disadvantage of triggering an avalanche by hand is that the explosive charge comes to rest on the snowpack and does not, as would be optimal, detonate 0.5 to 3 meters above the snowpack. This disadvantage can be partially compensated with a ridge boom, but this device is built permanently at one point, whereby the advantage of triggering avalanches by hand - mobility according to the snow conditions - is lost.
Hand blast of avalanches from the ridge arm
A ridge boom is a rotatable construction (e.g. similar to a very simple derrick crane ), in which an explosive charge can be lowered over a ridge into a steep avalanche slope so that it can detonate over the snow cover with the maximum triggering energy for an avalanche.
Explosive rod / explosive bar
Similar to the ridge boom, the explosive charge is pushed out over the ridge with an explosive rod / explosive bar. The explosive rod / explosive bar consists of several extendable or pluggable rods. Depending on the desired detonation point, these can be placed on a ridge and extended / plugged together up to 10 meters.
Explosive sledge
A blasting sledge is an aid to hand blasting. It consists of two runners that are connected by a rod on which a rod-like arm is located. The explosive charge is attached to this in such a way that it can detonate above the snow cover. The blasting sled is mainly used on steeper slopes where hand blasting is difficult to carry out. Blasting sleds are often built from old skis themselves.
Authority to issue orders and liability
The order for the use of explosives to trigger an avalanche for a specific area is usually made by the avalanche commission or a similar institution. A person authorized to blast is generally not authorized to carry out avalanche explosions. With regard to the execution of the blasting work itself, however, the person authorized to blast alone is responsible and authorized to issue orders. It determines how the explosives and detonators will be transported by whom, how much explosives will be used, from where the corresponding charge will be detonated, how the locking and safety measures are to be implemented, who will accompany him and who will detonate the explosive charge, etc.
Detection
Whether the detonation and the success of the explosion occurred is recorded with a visual inspection and manual documentation in advance.
Failure elimination
In order to be able to find failures ( duds ) more easily, the explosives are often equipped with a RECCO strip. Failures are to be recovered as quickly as possible. However, a minimum waiting time must be observed (in Austria e.g. 15 minutes after ignition until recovery).
The time fuses attached to an explosive charge must be cut off near the explosive immediately after recovery in order to reliably prevent re-ignition.
See also
- List of avalanche accidents , list of avalanches and landslides, landslides and list of disasters
- Search for avalanche victims , avalanche shovel and avalanche cord
Web links
- Avalanche explosions at Nebelhorn , video BR-Mediathek 5:13
- Déclenchement d'avalanche - Setting off an avalanche
Individual proof
- ↑ Lukas Stoffel: Comparison of the blasting methods: Gazex, Avalanche Guard / Mast Inauen-Schätti, Wyssen Sprengmast, Avalancheur , Comparison of methods for artificial avalanche release, WSL Institute for Snow and Avalanche Research SLF, January 24, 2013, p. 3.
- ↑ Stefanie Buchinger: Artificial triggering of slab avalanches - comparison of the methods used in Austria, master's thesis, University of Natural Resources and Life Sciences, Vienna 2014, p. 61.
- ↑ Stefanie Buchinger: Artificial triggering of slab avalanches - comparison of the methods used in Austria, Master's thesis, University of Natural Resources and Life Sciences, Vienna 2014, p. 62.