Accident: Big Springs 2/20/2011

Observer Name:

Kobernik, Nalli, Patterson

Observation Date:

02/22/2011

Occurrence Date:

02/20/2011

Occurrence Time:

Unknown

Region:

Big Springs
South Fork
Provo Canyon
Provo

Location Name:

Big Springs

Location

40° 18' 20.2104" N, 111° 32' 46.3416" W

Avalanche Characteristics

Elevation:

7400'

Aspect:

Northwest

Slope Angle:

Trigger:

Skier

Trigger: additional info:

Unintentionally Triggered

Avalanche Type:

Soft Slab

Weak Layer:

Facets

Depth (avg):

Width:

50'

Vertical:

500'

People Involved

Caught:

Carried:

Fully Buried:

Accident & Rescue Info

Accident & Rescue Summary:

Two male ski tourers were ascending the Big Springs drainage. About 2.7 miles from the parking lot they started to divert off the main trail and ascend toward a ridge. They were making switchbacks up a slope when they triggered an avalanche. The avalanche propagated about 300 feet above them. One skier was able to grab a tree and avoid taking the ride which the other skier did. He took about a 300 foot ride and was strained through some aspens and completely buried near the toe. His partner who did not go for a ride located him with an avalanche transceiver and dug him out from under about 4 feet of snow. He was uninjured and they were able to return to the parking lot on their own.

Terrain Summary:

The avalanche path was a not well defined gully feature.

Terrain Photos:

Weather & Avalanche History:

We observed two large natural avalanches that most likely occurred around the same time as the accident. They probably released just a little earlier.

After a good start to the winter season with abundant snowfall in the Provo area, January and the first part of February did not produce much accumulation. Surface hoar formed in early January and was buried in tact. A rain event occurred on January 16 which produced a crust with varying thickness. Faceted snow formed near the crust and is most pronounced below the crust. This weakness was what failed in the two large naturals. However, this was not the weakness at the accident site.

The weakness at the accident site was some not very well pronounced facets that formed Feb 17 and 18. 3 to 5" of snow that fell on Feb 16 had slightly faceted and was the weak layer.

General Comments

A couple of things to note here. This accident occurred during the heaviest snowfall. It demonstrates how avalanche conditions can spike during times of high precipitation intensity.

If you choose to travel in the backcountry during periods of high danger it is imperative that you travel on ridges where there is no avalanche terrain above you. Drainage bottoms and any steep slopes should be avoided. The slope that these skiers were ascending was not all that intimidating. However, even the most unassuming slopes can be lethal during a violent storm like was occurring.

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