Avalanche: No No Name 2/12/2012

Observer Name: 
Primomo
Observation Date: 
02/12/2012
Occurrence Date: 
02/12/2012
Occurrence Time: 
Morning
Region: 
Salt Lake
Park City Ridgeline
No No Name
Location Name: 
No-No Name Bowl
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Location

40° 37' 53.976" N, 111° 33' 47.4444" W
Avalanche Characteristics
Elevation: 
9700'
Aspect: 
East
Southeast
Slope Angle: 
Unknown
Trigger: 
Natural
Avalanche Type: 
Soft Slab
Weak Layer: 
Facets Above Crust
Depth (avg): 
8"
Width: 
500'
Vertical: 
400'
General Comments

Noticed a very fresh soft slab avalanche in No-No Name while digging some pits with the class today. Crown was very wide and wrapped from the main E facing bowl to a SE aspect, and connected through aspen trees to the right out of frame of the photo.

No Name Bowl also slid with a wide crown, but didn't get a great look at it with limited visibility.

Remotely triggered a small slope while skiing down the SE ridge of No Name from 60ft. away.

Weakest layer seemed to be a combination of buried surface hoar and near surface facets. Both diurnal recrystallized and radiation recrystallized noted.

-Test results on SE aspect at 9400ft, at NSF/crust 15cm down; CTE Q1 (Sudden Planar) down 15cm. ECTP: 11 down 15cm.  PST 25/100 (End).

-Test results on NE aspect at 9400ft at SH/NSF layer 10cm down; CTE Q1 (Sudden Planar). ECTN 5. RB2 80%.

at basal facet layer 80cm down; CTH Q1 (Sudden Collapse). ECTP: 30. RB5 100%.

Interesting combination of weak layers demonstrated by the Rutchblock test. The upper layer failed first, then with some additional loading (jumping) the basal facets failed completely. This makes me think after a slide runs within the upper snowpack, the bedsurface should not be automatically assumed to be safe.

No-NonameAvy.jpg
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