The Zwölferkogel Avalanche
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| Overview of Zwölferkogel avalanche on 23.02.2019. The avalanche extended to the Finstertal reservoir (2300 m). photo: 24.02.2019) |
Yesterday, on 24.02, we examined the site of the accident below the Zwölferkogel in the Kühtai where a person died. As described in the previous blog, it was a small slab avalanche. The cause was a recent snowdrift problem. Due to very strong, in some cases storm-strength winds, a hardened wind crust formed on the snowpack surface on top of softened layers. The avalanche triggered when a mountaineer traversed the 35° gradient NE slope. The avalanche was about 15 m wide and 70 m long. The depth of the fracture is estimated to have been 20-30 cm. The person was buried 1 meter deep, and was found by an avalanche search dog.
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| Close-up of the avalanche. Parts of the avalanche flow were drifted closed by winds. The patches visible in photo are mostly ice patches, marking various levels of the reservoir. (photo: 24.02.2019) |
The stability tests which we conducted in the vicinity of the accident were able to locate a fracture below the wind crust, but fracture propagation was not (no longer) possible. This observation fits with the reports arriving today that freshly generated snowdrift accumulations were no longer triggerable. In isolated cases, triggering might still be possible at high altitudes on very steep, shady slopes.
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| Location of snow profile slightly north of the accident site at 2370 m, north, 26°. The uppermost hardened wind crust together with the lower-down softer, faceted layer created the prerequisites for the slab avalanche triggering. Our stability tests demonstrated only partial fractures. (profile from 24.02.2019) |
The Ammerwald Avalanche
As was seen yesterday, this avalanche occurred in Bavaria and will be investigated by our German colleagues. It is already clear that it was a glide-snow avalanche which triggered naturally in a forest clearance and then divided into three plummeting arms. The search for a still-missing person was continued today, but without results.
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| Glide-snow avalanche in Ammerwald. (photo: 23.02.2019) |
