Two male Japanese skiers were involved in an avalanche in the Goryu ski resort sidecountry on Saturday, January 28. One of them was caught in the avalanche and killed. Evergreen Outdoor Center and ACT have put together a detailed report, which is copied below. Condolences to the friends and family of the deceased skier.
Avalanche Involvement, Hakuba, January 28th, 2012
2 male Japanese skiers, 41 and 51 years of age, both were involved in a very large avalanche in the Hakuba side country, one buried and found dead, one survivor left to search.
On their third run off the South Faces outside of Hakuba Goryu ski resort boundaries the two men strayed skiers left of their intended run due to poor visibility. By the time they realised that they were off their intended course they turned back right and descended just into the top of the large south facing open bowl and at this point triggered the avalanche just after noon. The depth ranged from 1 to 2 metres in depth and the slide fractured the whole width of the bowl, reaching just over 500 metres maximum width. The avalanche, taking the 51 year old, ran down two separate drainages for a slope distance of 1500 metres, losing 620 metres of elevation. The debris washed 100 metres up the wall on the opposite side of the valley to finally rest against a dam in the valley bottom.
Due to the very poor visibility the survivor was not 100% sure where his partner was when the avalanche released, and thus unsure as to where he was carried. He proceeded to travel down-slope into the main skiers left drainage with his beacon on search, but he did not receive any signal. Making it all the way to the main debris, he met 3 others that had just descended through the treed slope skiers right of the slide. They were already in search mode as they were aware that the avalanche was recent, very large, and that there may have been someone buried in the debris. They met up with the survivor, one went for assistance, and the other two helped with the search. They were in the narrow run-out at the base of multiple starting zones with other riders descending. With a high probability of other avalanches being triggered on to them, they decided it was too dangerous to continue searching and returned to the base of the ski field.
The survivor continued to search until the authorities came and began an organised rescue effort. The victim was finally found dead, buried 5 metres deep, at approximately 1000 metres elevation in the skiers right hand drainage at 17:00 hours.
On field investigation of the fracture site on January 29th by members of ACT and Evergreen Outdoor Center it was found that the avalanche fractured and propagated within the faceted melt form layer between a melt freeze crust and the recent storm snow. The thaw crust formed on the 18th and 19th of January and buried on the 22nd of January was most pronounced on solar-affected aspects and has been found on slopes facing from east to west, up to at least 2200 metres. The slope angle in the start zone was an average of 40 degrees and convex in shape around rocks, trees and bushes. The avalanche is calculated to have a mass in excess of 50,000 tonnes and classified as a destructive size 3.5 and a size 5 relative to the path capability.
Recent storm snow ranging in depth from 1 to over 2 metres is heavily loading the thaw crust and weak, sugary textured, faceted snow grains. Clearing and stronger winds the morning of the 29th have created a wind slab over low density snow that is likely to facet and become weaker. Forecasted heavy snowfall early this week will continue to add greater load to the existing faceted weak layer and bury and load the wind slab of January 29th.
Backcountry travel on slopes greater than 35 degrees on all aspects is not recommended. Choose small terrain with low consequences and practice strict travel procedures. With deep slabs and facets associated with melt forms, test results are often unreliable. Absence of avalanches should not be assumed to be an indicator of stability. Avalanches will be easier to trigger from thin tensioned areas close to bushes, rocks and trees. The present weak layer may persist for weeks to come and further loading may increase the probability of large slab avalanches.
If in doubt take the route of lowest risk. This may mean returning the way you came.
ALPINE ZONE: HIGH HAZARD !! Stronger winds, colder temperatures and greater snow fall are all contributing to very unstable conditions in Alpine and Tree Line Zones. Watch out for avalanches from ALPINE ZONES travelling to the valley and into TREELINE and BELOW TREELINE ZONES.
TREELINE ZONE: HIGH HAZARD !!
BELOW TREELINE: CONSIDERABLE HAZARD !
This report was put together by Evergreen Outdoor Center and ACT, and is available on their Facebook page.