OFFICIAL REPORT FROM THE ALASKA SAFETY CENTER
ACCIDENT REPORT: EAST FORK MATANUSKA RIVER HEADWATERS, ALASKA
Prepared by: Doug Fesler and Jill Fredston, Alaska Mountain Safety Center, Inc. February 7, 2001
Date of Accident: Saturday, February 3, 2001 @ approximately 12:10 p.m.
Accident Location: Peak 7075, just north of the headwaters pass at the source of the East Fork of the Matanuska River, on the northern side of the Chugach Mountain Range, approximately 12 linear miles SSE of Eureka Lodge on the Glenn Highway.
Synopsis: Two snowmachiners were killed, four were caught, and one was nearly caught, in a human-triggered hard slab avalanche. At the time of the avalanche, the party of seven was ascending the main chute on the south side of Peak 7075.
The Avalanche: This was a large avalanche with big blocks of broken hard slab debris measuring the size of office desks to automobiles. A few were larger than dump trucks. The fracture line ran more than 3,000 feet, crossed two ridges, and cleaned out three separate bowls with two runout zones a quarter of a mile apart. The fracture depth varied from 1.5 feet to 15 feet with the average around 6 feet. The avalanche in the main path traveled more than a half mile and fell 1800 vertical feet from 7000 feet to 5200 feet. Snow was piled 35-40 feet deep in the runout zone and nearly ? mile wide. The other path was about 30% smaller, but no less impressive. The fact that four people managed to survive this slide is amazing.
Background Weather and Snow Conditions: The early winter was uncharacteristically mild for Eureka (typically -10? to +20? F) with few storms. This resulted in a shallow snowpack (around 2 feet deep) consisting mostly of weak, well-developed, faceted snow. In early January, a major storm hit the area adding 3.5-4 feet of new snow. Subsequent winds created widespread wind slab over depth hoar conditions. On the day of the accident, the weather was clear with occasional high clouds, cool (-10? F), and windless.
Terrain Factors: The accident site consisted of a long and narrow, slightly S-shaped chute bordered by steeper side walls. The main chute follows a north-south alignment and ranges from 23? at the base to 38? at the top, with steeper sidewalls ranging from 40? to 50?. A second chute originating from a large bowl to the east intersected along a northeast-southwest axis near the mid-way point of the main path. A prominent rock pinnacle is on the opposite (west) side of the main path immediately across from the second chute.
When the avalanche occurred in the upper portion of the main chute, the shear failure propagated into the second bowl and then into a third bowl to the southeast. Snow from the first two bowls emptied into the main chute, while snow form the third bowl descended a separate, almost parallel, path ? mile east of the main chute. The release zones were predominantly leeward (wind loaded) with southerly and westerly aspects. Anchoring was minimal, with most of the starting zones covered by tundra and scree interspersed by a few rock outcrops.
The Accident: At approximately 1210 on February 3, 2001, a party of seven snowmobilers were ascending the main chute, that leads to the top of Peak 7075 on the south side. They were traveling more or less in a line and spread over a distance of approximately 300 feet.
The riders in the lead, Dan and Clark were approximately two-thirds the distance up the slope when the avalanche released above and to the right (east) of them. David was approximately 30′ behind them, followed by Rick (60′ behind David), followed by Scott (60′ behind Rick), followed by Mike (60′ behind Scott.), followed by Shane 200′ below Mike. As the slope above and to the right (east) broke loose, each snowmobiler immediately attempted to escape to the west side. Dan, who was already in the process of turning his machine, was instantly flipped, tumbled, and carried with his machine 1500′ vertical downslope where he was buried under 8′ of debris and killed.
Clark managed to point his machine toward the west flank of the path, gun his engine, and momentarily escape onto stable snow adjoining the slide, until the curve of the terrain forced him back into the main path where the entire snow surface was in motion. Unable to stop, he was carried about 150 feet downslope until he was able to wedge his machine into some debris that had stopped. Most of the slide had passed in front of him, but some snow was still sliding when he came to rest.
David, who was attempting an escape to the west side, was hit and flipped (end-over) upside down almost immediately. Trapped under his machine, his face pressed under the windshield, he was carried nearly 1500 vertical feet downslope before stopping. He estimated he was carried that way for 95% of his ride, until at the last moment, he popped to the surface next to his machine (which also flipped over) about 50 feet below where Dan was found. The machine was later found to have been severely damaged by blunt impact. Rick was roughly 40′ above the rock pinnacle when he saw the snow coming and tried to get to the west side of the path. At the last moment, he leaped off his machine and ran upslope as the machine was swept away behind him. The machine was carried approximately 1500 feet downslope and deposited 5 feet below David and his machine.
Scott never had a chance. He saw the wall of churning debris, pointed his machine to the west, and tried to reach safety. But the rock pinnacle blocked his escape. Hit from behind by the force of the snow, he and his machine were lifted upward against the face of the rock. In a desperate attempt, he repeatedly grabbed for a handhold as his machine was swept away beneath him. Unable to hold on, Scott was pulled from the face and swept into the blocks of moving debris. His machine was last seen flipping end over end down the gully.
Mike, 60′ below the rock, saw the slope on his right begin to buckle and move. Figuring he only had seconds to reach safety, he methodically pointed his machine toward the west side, and tried to escape. Seeing Scott’s predicament and being further downslope than Scott, he figured he had slightly more time in his favor and no rock face to obstruct his escape. When almost to the edge, he felt his machine starting to lift on the right side. He stood, leaning to the right. As it lifted on end, he leaped for the edge of the path and scrambled to safety.
Shane was the luckiest of all. Two hundred feet below Mike, he saw the avalanche breaking away from the face above, turned his sled downhill, and rocketed out toward the southwest. Because his back was to the avalanche, he was unable to note the positions of his partners.
The Rescue Attempt: When the snow came to rest , the runout zone looked something like a battlefield with slab blocks ranging in size from office desks to trucks. The debris was piled 35-40′ deep in the center of an area measuring roughly 3 city blocks by 3 city blocks. Mike and Rick were within sight of each other midway along the western side of the path. Clark was out of view above the S-curve, further upslope near the top. Shane was out of view below the lower S-curve on the west side. David was now standing by his machine on the surface of the rubble. Mike made the first head count using the CB radios each of them carried. David and Shane moved toward each other on the lower portion of the path, while Mike, Rick, and Clark grouped above. Two other groups of snowmobilers, comprised of two people each, responded to the site from the valley below.
By 1225, the group gathered together and a plan was hatched. One team of two snowmobilers departed for help. Their plan was to get within cell phone range and call the Alaska State Troopers. Those with beacons spread out across the surface and conducted a beacon search. (Clark, Mike, Rick, and David carried beacons. Scott’s beacon was found at his home later. Shane and Dan, who were new to the group, did not own beacons.) With the only two probes the group had, two people started probing for Dan and Scott, hoping to get lucky (all other probes had been stored with the machines, which were buried). Others started digging out Scott’s machine which was partially visible.
By 1300, Scott’s machine was out and Dan’s machine was located directly under Scott’s. By 1315, Dan’s machine was half out and probers struck Dan 2? to 3 feet under his machine. By 1330 his head and chest were uncovered, but it wasn’t until 1350 that he was completely excavated, pulled free, and examined. His airway was open. CPR was started at 1355 and terminated at 1430 without success. Meanwhile, probing continued for Scott. By 1430, prospects for finding Scott looked slim in light of the size of the slide, the limited rescue gear and personnel on site, and the fact that the survivors were cooling down.
As the sun went behind the ridge, thoughts turned toward evacuation. Getting the group back to Eureka Lodge (roughly 15 miles by snowmachine) would not be easy. Five machines were seriously damaged (ranging from $800 – $4500 in damage) and one was stranded high in the path.
After an hour of patching together the more repairable machines, the group headed toward Eureka. Very quickly it became apparent that Rick was becoming severely hypothermic as he was nodding off and acting sluggish. The group soon encountered the two snowmobilers who had gone for help earlier. They had contacted the Troopers and been told to make a signal fire at their location to guide the rescuers to the site. Rick was warmed by the fire and given liquids and food.
Formal rescue response (Alaska Mountain Rescue Group, Alaska Search and Rescue Dogs, and Alaska Mountain Safety Center personnel) arrived on scene by approximately 1700. They were met by a Trooper and the two snowmachiners who had responded earlier. They pieced together the sequence of events at the accident scene, assessed the site as safe from further avalanches, conducted a thorough beacon search of the runout zone, conducted an initial dog search, and transported Dan’s body in the Army National Guard Blackhawk helicopter. Fuel vapors from the helicopter had sickened several of the rescuers and probably disabled the dogs as well.
Searchers departed the site by 1930, with a plan to return the next day with more searchers and the witnesses. They spent the night at Eureka Lodge where they were able to interview the witnesses. The next day’s plan entailed searching the area with SAR dogs and probe lines. The bad news was that the first helicopter (an Alaska Fish and Wildlife Protection, Robinson 44) into the site crashed in flat light and was totaled. The good news was that pilot and two passengers were uninjured. A Blackhawk helicopter delivered additional rescuers to the site within 30 minutes.
By 1030, two SAR dogs alerted in a high probability area and probers confirmed the find. Scott was uncovered from 10′ of snow and the mission was terminated. Rescuers included members of the National Ski Patrol, Nordic Patrol, the Alaska Mountain Rescue Group, Alaska SAR Dogs, the Alaska Mountain Safety Center, the Alaska Snowmachine SAR Recovery Team, the Mat-Su Motor Mushers, and the Backcountry Avalanche Awareness Rescue & Recovery Team.
Terrain: steep, smooth, and leeward. Note: Steepness adds stress. Smoothness provides poor anchoring of the snowpack. And leeward slopes are subject to greater loading and, thus more stress.
Weather: Previous weather created an unstable slab of variable thickness sitting on top of a weaker layer of faceted snow beneath. Current weather contributed to luring snowmobilers to a potentially dangerous area.
Snowpack:. In an unstable snowpack, the strength of the slab and the underlying weak layer are nearly equal to the stress exerted upon them by the weight of the snow, any additional load from new snow, and the stress caused by slope angle.
When the stress finally equals the strength of the slab (and the weak layer) at all of the boundary regions of the slab, an avalanche results. Often, it is the additional weight of a person and/or snowmachine that tips the balance. In this case, seven machines and riders — perhaps 4500-5000 lbs. of load and vibration- were applied to an already stressed slab. The result was immediate and catastrophic. Clues to instability included evidence of recent avalanches in the area, hollow sounding snow, wind slab texture on the surface, and detectable easy shears from stability tests. The avalanche was initiated in an area where the snow was thinner and weaker, and thus more susceptible to the weight of people and machines. From here, shear failure propagated into deeper and stronger snow above.
Human Factors: For the most part, the victims did not have the training, knowledge, or skills to evaluate the hazard or the risks of avalanche terrain and snow conditions their powerful snowmachines gave them access to. Though their snowmachining skills were considerably greater than their hazard evaluation skills, traveling through exposed terrain as a group, rather than one at a time, significantly increased the risk. Only one member had any previous avalanche training and his previous experiences had involved mountaineering and skiing where the process of hazard evaluation occurs at a slower rate, with more input, and greater participation. He felt his ability to assess conditions was limited by tunnel vision (through a helmet’s visor), speed, and the inability to hear and feel subtle sounds of the snow underfoot.
Conclusions: This instability is of the type that persists for a long time, yet is easily detectable. In essence, the group seems to have been lured into the den of the dragons by capable machines, favorable weather, spectacular scenery, and the idea of having a good time with friends. This group was not knowingly reckless, but they underestimated the strength of a thin snowpack and the amount of wind loaded snow in the starting zones and did not factor in the consequences traveling closely together into a terrain trap. Note that even if the victims had been wearing avalanche beacons, the outcome would not have changed because of the deep burial.
Rescuers dig out 2nd body
EUREKA: Expert amazed anyone survived huge slide
By Lisa Demer Anchorage Daily News (Published February 5, 2001)
The avalanche that killed two snowmachiners Saturday south of Eureka Lodge was a massive slide that measured more than half a mile across where it broke away from the slope, two avalanche experts said Sunday. Alaska State Troopers on Sunday identified the men killed as Scott Boland, 31, and Danny T. Hunka, 32, both of Anchorage.
Searchers found Boland’s body about 11:30 a.m. Sunday buried under 10 feet of snow, not far from where his snowmachine was dug out the day before. Hunka’s body was found Saturday afternoon. The two were riding in a group of seven snowmobilers. Another in the group, Richard Hanson, 28, ended up underneath his snowmachine but wasn’t buried. “It was a really big avalanche,” said Doug Fesler, an avalanche expert who was at the scene Sunday. He estimated that the base measured three city blocks by three city blocks. Blocks of snow debris were 25 to 40 feet high. “It was really quite amazing that any of those guys survived.”
The avalanche occurred near the east fork of the Matanuska River, about 80 miles east of Palmer. Around noon Saturday, the riders headed up the slope single file. The snow near the top riders broke away under the weight of their machines, said Jill Fredston, an avalanche safety expert who led the search for the missing snowmachiner on Sunday.
“They knew it was a big slide. They were all running to try to get out of it,” said Fredston, who runs the Alaska Mountain Safety Center with her husband, Fesler. The fracture wrapped around the mountain, and Fesler estimated it to be 3,000 feet wide. The slab of hard-packed snow that broke away ranged from 18 inches to 15 feet thick and its average depth was 4 to 6 feet, Fesler said. Underneath the hard pack was a shallow, weak layer of loose, granular snow common in the area. The pack hadn’t bonded with the loose snow — a prime avalanche condition.
The two who died were carried more than 1,000 feet down the slope. At least a couple of those who survived got off their machines and ran up a steep sidewall of the gully, Fredston said. Blocks of snow the size of motorcycles, Subarus and dump trucks tumbled by at about 50 mph, she said. “These guys are not stupid guys. They are not fools,” Fredston said. “They weren’t trying to be reckless.” Still the area had signs of danger: some natural avalanches and slopes wind-loaded with snow.
Conditions remain ripe for more avalanches, especially on the north end of the Chugach Range, Fredston and Fesler said. “This instability will be with us until it melts in the springtime or when it comes down through avalanches,” Fesler said. About 70 regular rescue volunteers, plus some of the surviving snowmachiners, gathered at Eureka on Sunday to help, said Dan Hourihan, a state parks ranger who coordinated the base operations from Eureka Lodge for the Alaska Mountain Rescue Group.
Two Army National Guard helicopters ferried volunteers from the lodge. Others traveled the 25 miles by snowmachine in the zero-degree cold. A trooper helicopter with Fesler and another volunteer aboard crashed around 10 a.m. Sunday near the search site. No one was hurt. Fesler said the flat light at that time of day made it almost impossible to distinguish the ground from the air, and a helicopter float caught the snow as it was trying to land. It flipped hard onto its right side.
Fesler then climbed the slope to check for further avalanche danger. Two search dogs, Chili and Bean, pointed rescuers to the area where Boland’s body was found, Fredston said. Volunteers used 12-foot probes to find him.
Avalanche kills snowmachiner
EUREKA: Search will go on for a second man presumed dead; one rider was rescued
By Molly Brown Anchorage Daily News (Published February 4, 2001)
A group of snowmachiners Saturday triggered an avalanche on a slope south of Eureka that killed one member of the group and left another missing and presumed dead. A third man was carried downslope and trapped beneath his snowmachine until he was freed. Alaska State Troopers didn’t identify the two victims but said they were men in their 30s from the Anchorage area.
The group of seven was snowmachining about 20 miles south of Eureka Lodge near the east fork of the Matanuska River just after noon, Alaska State Troopers said. The seven were traveling in a line up a 35- to 45-degree slope when the slide started, troopers said. Most slides occur on slopes between 25 and 60 degrees. “They were tremendously lucky to not have more fatalities,” said avalanche expert Jill Fredston, reached by phone at Eureka Lodge after the search was suspended Saturday night. “All seven were riding for their lives, and they are quite shook up,” she said. Troopers estimated the slide to be a quarter-mile wide and 8 to 40 feet deep. “It’s big, but I don’t know,” Fredston said of the dimensions. “I do know that it probably released at about 6,500 feet elevation and ran 1,500 vertical feet down.” Troopers received a report of the slide about 12:40 p.m.
As searchers — including Anchorage volunteers from the Alaska Mountain Rescue Group, Fredston, two rescue dogs and two handlers — were called in by troopers, snowmachiners at the avalanche site searched the debris. Six out of the seven snowmachiners carried emergency beacons and probes, troopers said. Two hours into the search, the group located the body of an Anchorage man buried under 9 feet of snow, troopers said. The group tried for 30 minutes to resuscitate him and continued to search for the missing man. Names were not released pending notification of relatives.
About 5:40 p.m., rescue workers arrived on the scene in an Army National Guard Blackhawk helicopter, said Maj. Mike Haller. A trooper helicopter with night vision capabilities was launched at 5 p.m. The search was suspended about 7:30 p.m. because of darkness, said troopers spokesman Greg Wilkinson. Rescue workers stayed overnight at Eureka Lodge, planning to resume the search at 8 a.m. today, Fredston said. Most of the group of riders headed back to their homes in Eagle River and Anchorage but planned to join the search today. Searchers found all of the snowmachines, Wilkinson said. Fredston said they will probe an area where there is a dip in the debris on the left side of the slide. “It is going to be tough,” she said. “Some of these blocks are Subaru size.” One worker at Eureka Lodge estimated that about a dozen people were snowmachining in the area, about 80 miles east of Palmer. It was cold and sunny, and workers at the lodge posted signs warning backcountry users of avalanche danger.
Over the past weeks, several feet of snow has fallen in the Eureka area, leading to heavy use by enthusiasts. Avalanche expert Doug Fesler said he and Fredston heard a report recently that two snowmachiners were partially buried by an avalanche a week to 10 days ago in the Eureka area. The two were watching others highmarking — racing up steep slopes to make the highest mark — when a slide came down. The avalanche left one observer with a broken arm, Fesler said, but the highmarkers escaped without injury. An Air National Guard helicopter picked up three snowmachiners stranded about 21/2 weeks ago when a storm dumped 31/2 feet of snow on them, leaving them lost and out of fuel.
They spent a night bunkered down in snow caves in the Talkeetna Mountains. Before Saturday’s incident, 13 people had died in snowmachine-related accidents this winter. The accidents have occurred statewide, from Fairbanks to Norton Sound. Several people drowned after breaking through or riding off of ice, one man died of exposure, and four deaths involved collisions. The National Guard helicopter returned to Anchorage on Saturday, Wilkinson said. The troopers’ Fish and Wildlife Protection helicopter remained on the scene. Fredston said additional rescue volunteers and rescue dogs will search the area today. Troopers do not want any volunteers.