On the 23rd of Feb at 10:15 am we made a full profile on Todorka’s North Face. Since the face was quite skied out we decided to dig below the large cliff band on the traverse just below the female couloir. Thus the particular location where we dug was wind affected and we observed a much deeper snow cover (2.7 m) than the average on the face.
We didn’t see any instability signs or previous avalanche activity on the face or on faces with similar aspect. The profile we did displayed a snowpack with a strong base. The layer of primary concern was a layer of graupel, 38 to 43 cm from the surface which had no cohesion. The weak layer was readily visible at the observation wall.
ECT test showed ECTP 21 down 40 cm on the graupel layer. On the CT we got twice the same results – CTH 22 (SC) down 40 again on the garupel layer, confirming our findings.
The above results are particularly worrisome as they mean that we have exactly the right characteristics in the snowpack to produce slab avalanches. The graupel is below 12 cm of very thick, coherent slab, which currently bridges the applied load with its strength and this is why we don’t see any reaction on the weak layer.
However, the stability may be poor at locations where the wind has deposited deeper snow. In addition with the expected snow fall this Thursday (27th of Feb), we may see a cycle of natural and human triggered avalanches.
Over the coming days we will be doing more tests at different locations on the face to confirm the existence and behaviour of the weak layer.
