Detailed Accident Report

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Date: 2002-01-21
Submitted By: Evan Woods, Stevens Pass Ski Patrol
Place: Tunnel Creek, near Stevens Pass
State: WA
Country: USA
Summary: 5 snowboarders caught, 1 with serious injuries.


Informational report on two avalanche accidents in the Tunnel Creek area near Stevens Pass, WA?01-21-2002. Report prepared by Evan Woods, Stevens Pass Professional Ski Patrol

Incident Description: Time and Date?Monday afternoon, 1/21/02, at approx. 15:00 hrs. Five snowboarders were involved in two avalanches that were possibly connected. One incident involved two snowboarders, one cutting a soft slab that caught a second below him. The second incident involved three snowboarders being caught in an avalanche in the same terrain feature above a creek drainage.

Location: The south side of Cowboy Mt. going into the Tunnel Creek drainage. S-SW face slope @ approx. 4600' elevation. Access to Tunnel Creek is via hiking route off of Seventh Heaven chair lift located in Stevens Pass Ski Area. Tunnel Creek is a backcountry run and not part of the ski area. The Avalanches happened at the lower end of the main glade, falline from the high point of Cowboy. The glade funnels into a steep creek with very tight trees on both sides of the creek. The right side of the creek has open convex slopes 35-40 degrees rolling into the creek, the left side has some ribs and small chutes feeding into the top of the creek. These features create a gully type terrain trap that is approx. 100-150 meters across.

Synopsis: A group of approx. 7 snowboarders descended from the top of Cowboy down the main high point glade. Where this glade feeds into the creek drainage two of them traversed to the left. One of the snowboards came over a steep roll and released an SS-AS-2-0 approx.30-40cm deep and 30-40 meters wide. This slide caught a snowboarder below him and took him for a short ride until he was stopped by a small tree. He had a minor injury to his Rt. hip but was able to continue to ride. At approx. the same time (because all of the riders had ridden down the upper glade together ) three snowboarders were caught in a slide on the right side of the gully area. I only talked to two of the riders involved in this slide so details are a little sketchy. One snowboarder ( rider #1 ) riding into the top of the creek from the left when he saw another rider above and to his right, then he saw snow fracture across from him and above and behind him, he was caught in the slide and taken down the slope a short distance. The exact distance not know but probably less than 100 meters because at that point he would have entered the steep creek drainage below. This rider was OK when he came to a stop. He looked around and saw two other riders that had been caught in the same slide. One of the riders ( rider #2 ) appeared to OK but shaken up with cuts and bruises. He said he was 2 or 3 turns into to the gully when he got hit from behind. The third rider ( rider #3 ) was not moving and appeared to be injured. Rider #1 went over to him and saw that one of his feet had been pulled out of his boot and his boot was still attached to his snowboard; his gloves were also gone. He appeared to have an unstable upper arm fracture and possible leg fracture; he was alert but disoriented. At this point rider #2 went down to the highway to get help while rider #1 carried the injured rider down the steep creek sideslipping on his board approx. 1000 vertical feet where the creek opens up. When they came out into the opening at the bottom of the creek they were seen by some other skiers and snowboarders who improvised a sled with snowboards and hauled the injured victim out approx. one mile to the highway where an ambulance was waiting.

Snowpack and Slide Details: A crown profile was not done on the slide as none of the Ski Patrollers that went to the area the following day felt that it was safe or wise to enter that area with the instability present, hang fire and additional loading of 20-30cm of new snow overnight. A quick look at the snowpack on a similar aspect and elevation showed a slab structure consisting of 4F snow 40cm deep sitting on top of 25cm of 1F snow on top of the rain crust. The upper 4F slab sheared very easy on 1-1.5 mm surface faceted snow on top of the 1F layer. This coincides well with statements made by involved parties the bed surface of the slide was soft and he didn?t feel any hard or icy layers.

The crown from the slide on the right side of the creek was observed from a distance, it appeared to have pulled out two open convex rolls into the creek drainage that were 30-40 meters across SS-AS-2-0 approx 35-40 cm deep. Slope angles were approx. 35-38 degrees. Debris from the slide was visible approx. 1000 vertical feet lower where the creek feeds out into the open. This debris had two fingers approx. 10-20 meters wide and up to 5 meters deep. The crown from the slide released on the left side of the creek was not visible from the location of observation.

Summary: The possible connection might be that the slide released by the snowboarder on the left side of the may have triggered the slide on the right as they were all in the same area at the same time. Statements from the injured party that was helped out were not available, so the trigger of the slide he was involved in was not determined. Of the five riders involved one had a shovel and transceiver, the others did not. All five of the riders were familiar with the terrain, all five had ridden the area at least once that day, and three of the five had some formal Avalanche Awareness training.

--------------Evan Woods Stevens Pro Patrol-------------------