Detailed Accident Report

Back to accidents page

Date: 2001-04-18
Submitted By: Matt Hill
Place: Sun Bowl, Mt.Shasta
State: CA
Country: USA
Summary: 3 backcountry skiers caught, three partially buried

Date: 4/18/01

Submitted By: Matt Hill,U.S.F.S.Mt.Shasta Avalanche Center

Location: Sun Bowl, Mt.Shasta, CA, USA

Fatalities: 0 Activity: Skiing

Summary: 3 backcountry skiers caught, three partially buried

Date and Time: April 14, 2001 1600hrs.

Avalanche: HSAS2O (Hard Slab, triggered by a skier, class 2, bed surface

was old snow layer). Approximately 8,400' on the south side of Mt.Shasta

in a southwesterly facing bowl known as Sun Bowl.

Accident:

There was a large group of 36 conducting a backcountry festival. The

purpose of the event was to ski as well as educate people to backcountry

awareness. They chose to use the Sun Bowl area on Mt. Shasta. They dug

snow pits along the way and performed different tests. They entered the

bowl from the bottom and gained the ridge line to the west to get to the

top of the bowl. The group made three laps in the bowl, skiing various

aspects. The slide was triggered on the southwestern aspect by a lone

skier, where there were several other tracks. The majority of the skiers

were skiing in the southeastern portion of the bowl where it was less

steep (28 degrees) and more sun affected. The starting zone of the slide

was more wind affected and slightly steeper (35 degrees).

The slide occurred when one skier traversed into the southwestern aspect

of the slope and found the sweet spot. The fracture propagated across

the slope approximately 500 feet with slope angles of 25 to 35 degrees.

It was a hard slab avalanche about a 1-4' crown with 3-9' of firm snow

in the deposition zone. The victims including the skier who triggered it

rode a chunk of hard slab, while the others scurried out of the way of

the avalanche. The two victims that were down slope were almost at the

bottom of the slope, which was 800' vertical and ran 1,500' linear. The

victims were spotted visually and kept in sight throughout the whole

event was witnessed by the other skiers. The victims were accounted for

within 3 minutes. The skier who triggerd the slide was knocked down and

uninjured. One skier was buried up to his waist and uninjured. The other

woman was knocked down and uninjured.

Weather:

The weather preceding the incident was strong NW winds, clear days and

cool temps. The weather that day was clear, calm winds and the first day

of warm temps, with light cloud cover. The temperature in the morning

was 19F degrees and warmed to 40+F degrees at 16:00.

Snow Data:

There was 50cm of pencil hard wind deposited affected snow, with a 2cm

layer of 1mm intermediate facets sitting on top of a 5cm four finger

hardness wind affeted snow. Below that was 30 cm of 1 finger rounded

grains 1-2mm. The failure was beleived to have occurred on the faceted

layer 50cm below the surface.

Conclusion:

The accident could have been prevented by heeding the signs of day such

as increasing temps, slope angle, aspect and recent wind affects. The

pit that was dug was not in the area that was skied and the group

mentally could have been tempered with a greater emphasis on heeding the

clues throughout the day.