From: haas%basset.utah.edu@cs.utah.edu (Walt Haas)
Subject: Re: Avalanche death in Utah
Date: 11 Apr 92 09:47:37 MDT
Organization: University of Utah CS Dept

In article <122930127@hpfcso.FC.HP.COM> ericr@hpfcso.FC.HP.COM (Eric Rentschler) writes:
>Also, what were the details in the "LaSalle incident"?

Well, I was hoping that somebody else would report on Thursday's talk, but
they're probably all too busy :-(

1) the Mineral Basin avalanche
	The victim and several friends rode lifts to the top of Snowbird,
	then left the resort boundary, for the purpose of filming extreme
	skiing in Mineral Basin.  As they entered the slope they intended
	to ski they encountered somebody else who was in the process of
	digging a pit.  They stayed to observe and noted the weak buried TG
	layer about 18 inches below the surface.  This did not affect their
	decision of what to ski; their minds had been made up before the
	beginning of the trip.

	The victim positioned himself at the top of the intended slope,
	which had an angle of 38-40 degrees, while the rest of the party
	got into position for filming.  The slope had a rock band below
	with several narrow chutes of about 50 degree angle; the intent
	was to show the victim skiing one of these chutes.  Below the rock
	band the slope angle eased, becoming almost flat after another
	1000 or so feet.

	The victim began skiing.  After roughly 18 turns, while he was still
	on the upper slope, the snow fractured along a crown line well above
	the victim.  He skied to his right, almost reaching a small clump
	of trees, before he was carried over the rock band.  When the snow
	with the victim reached the lower slope, it released a much larger
	avalanche which ran about 1000 feet to a deposit on the flats.

	The film crew immediately skied down to the deposit, a process taking
	about 10 minutes.  Since all had avalanche beacons they were able
	to locate the victim and begin digging within 2-4 minutes.  It took
	another 10 minutes to reach him, at a depth of about 7 feet.  About
	that time the Snowbird ski patrol, including a physician, arrived;
	a patroller had witnessed the accident from the top of the tram.
	The victim was given medical care and taken to the hospital by
	helicopter, all to no avail.  The ME listed cause of death as
	asphyxiation, but the victim was severly traumatized by being dragged
	over the rock band and would probably have died of internal injuries
	if he had had enough oxygen.

	The slope aspect was NE.  The avalanche occured in new snow which
	was beginning to consolidate, but the victim was skiing in powder
	at the time of the slide.  Inspection of the bed surface revealed
	that the victim had been passing through a particularly thin layer
	of snow over some buried rocks at the time he triggered the slide.

2) the Gold Basin avalanche.
	There had been no snow in Utah from about January 7 to February 8.
	During this time skiing conditions deteriorated and skiers became
	restless.  Needless to say, TG snow formed on northerly exposures.
	When it finally began to snow, the LaSal mountains received several
	small storms of 2 or 3 inches a day.  All these storms had
	temperatures starting warm and becoming colder, so each new fall
	had good opportunity to bond to the previous snowfall.  By February
	12 there was enough new snow to create good skiing.  On that
	morning Mark Yeats, professional avalanche forecaster for the
	LaSals, and five friends set out to ski in the Gold Basin area.
	All six were expert backcountry skiers and well trained in snow
	stability evaluation.  They had recently formed an organization to
	do avalanche search and rescue, and this trip was planned as their
	first training run as a group.

	They drove to the end of the plowed road then skied up unplowed
	road, constantly evaluating and observing snow conditions.  Below
	the tree line they heard WOOMPH sounds as snow collapsed on weak
	layers under them.  Above the tree line the WOOMPH sounds stopped.
	They observed that a couple of steep north-facing chutes had had
	natural avalanches, starting on slopes of about 45 degrees, which
	ran until the slide came to a slope with a 35 degree angle, then
	stopped.  They took this as an indication that snow at 35 degree
	or smaller angles was stable enough to stay put even on northerly
	aspects when loaded from above by an avalanche.

	They skied Goldminer Gulch, a steep chute with a southerly aspect,
	without incident.  They entered the trees at the bottom of Gold
	Basin and heard more collapsing noises in the trees.  They proceeded
	north toward Talking Mountain Cirque, their intended destination.
	stopping for lunch on the way.  After lunch they started up into
	the cirque, traveling in a straight vertical line up the slope.
	They began on a very moderate slope which gradually became steeper.
	The group consisted of Steve in the front; about 75 feet below
	were Mark, Maribel, Bill and Jeremy clumped together in a group; and
	finally well below the group was Craig.

	As they proceeded up the slope they stopped several times to discuss
	snow stability.  They were well aware of the TG layer below, but
	the other factors mentioned indicated good bonding of the new snow.
	Finally they reached a decision to turn around and ski out.  They
	were getting organized to remove their climbing skins when there
	was an enormous WOOMPH which was heard by the four clustered in
	the middle.  They discussed this sound for about ten seconds when
	Craig, the lowest, looked above them, saw not one but three fractures
	and yelled "Here it comes!"  Steve scrambled to his right and Craig
	scrambled to his left.  All six still had their skins on so movement
	was clumsy.

	All six were completely buried.  Steve and Craig were only buried
	about one foot deep.  Steve managed to extricate himself, a process
	taking about 20 minutes, then switched his beacon to receive and
	began searching for the other five.  He quickly picked up a signal
	and dug down to find Mark (this would have been at least 30 minutes
	after the slide).  Steve began CPR on Mark despite the lack of a pulse
	but was getting no results, when out of the corner of his eye he
	noticed a dark object waving above the snow.  It was Craig's shovel;
	Craig had been able to move enough snow from around his shoulders
	to reach onto his back for his shovel and begin digging out.

	Steve abandoned CPR on Mark and helped Craig dig out, a process
	that involved digging down about six feet to release Craig's feet
	from his skis.  This took perhaps another 15 or 20 minutes.  The
	two of them together searched for and located the other three,
	finding Bill buried near Craig and Jeremy and Maribel buried one
	on top of the other.  In all cases they performed CPR to no avail.

	About 5:30 PM Steve and Craig gave up and skied out, reaching their
	car about 7:30 and the town a little after 8 PM.  A helicopter
	was dispatched from Salt Lake City on the 13th, but was unable to
	reach the scene of the disaster because of weather.  On the 14th
	the helicopter flew in to Gold Basin through the moderating storm,
	with the party using explosives to release avalanches on the slopes
	surrounding the basin.  Almost every slope in the basin slid.
	Avalanche debris covered the bodies to a depth of many feet.

	When the body recovery party reached the scene they were able to
	quickly locate the bodies of Jeremy and Maribel because their beacons
	were still transmitting.  The other two bodies could only be found
	by probing, an extremely difficult process involving many false hits
	and dry holes.  Some holes were dug as deep as 18 feet without
	result.  The bodies were finally located by probing with the help
	of dogs which were able to scent the bodies through the probe holes
	(the snow was too deep for the dogs to scent through unprobed snow).
	All bodies were under 10 to 14 feet of new avalanche debris.

	The party had been on a slope of about 30 degrees when they triggered
	the avalanche.  The fracture line was on a slope of about 35 degrees.
	Stress induced by the group propagated up slope to the weakest point.
	The stress was increased by the clumping of the group.  The fact that
	they approached from below made it impossible for them to evaluate
	the starting zone before entering the slope.  The fact that all six
	were on the avalanche slope simultaneously guaranteed the death of
	anybody who couldn't dig himself out.

-- Walt

Newsgroups: rec.skiing