Detailed Accident Report

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Date: 2006-02-08
Submitted By: AMRG; B. Romberg
State: AK
Country: USA
Fatalities: 1
Summary: 2 snowshoers caught & carried. 1 buried and killed


Flattop Mountain: 1 triggered, 2 caught, 1 killed.

February 8, 2006.

Written by Bill Romberg, Alaska Mountain Rescue Group


Two male snowshoers were descending on the SW side of Flattop at approximately 2600 feet in the vicinity of the summer trail as it enters the ?wind tunnel? section between Blueberry Hill and Flattop around 1900 when they triggered an avalanche (N 610 05` 45.87?, W 149 40` 26.98?. The lead person (John Lorentzen - reporting party, age 24) was about 75 feet from the intersection of the Blueberry Hill trail and the summer Flattop trail where it branches east up Flattop (from the end of posts) when he heard a loud ?crack?. He turned to look uphill and saw the avalanche starting and immediately ran straight downhill to a wind scoured knoll. He was not buried in the debris. His snowshoeing partner, Brian Mulvehill (34) was approximately 100 feet above and behind him to the southeast on the sloping bench at the base of the 37-40 degree snowslope on the east side of the ?wind tunnel?. Mr. Mulvehill was caught in the avalanche and completely buried about 60 feet uphill and 30 feet south of John?s exit point. Mr. Mulvehill was approximately 20? from the toe of the debris in this area of the slide path. Neither subject had any avalanche equipment (avalanche transceiver, probe, or shovel). Rescue was initiated by survivor via call to 911. Anchorage Fire Dept, Alaska Search and Rescue Dogs, Alaska Mountain Rescue Group responded and affected body recovery. Body of buried subject located by avalanche search dog under about 4 feet of debris and extricated after 2 hours--cause of death: suffocation.

The two snowshoers triggered a hard slab avalanche from a low-angled bench directly beneath on a 37-40 degree slope that is about 125 feet high. It is unknown which of the two snowshoers triggered the avalanche, but it is known that the pair was not descending the snowslope directly, but rather traversing the angled bench directly beneath the slope approximately 100 feet apart. The crown face was approximately 1000? long running the entire length of the slope and averaged 32 inches deep, increasing to nearly 4 feet at the southern end of the fracture line and tapering down to 24 inches or less at the north end of the gully. Two distinct hard slabs were noted in the crown face?a newly deposited 18-inch wind slab sitting on top of an older, denser, rain-affected slab. It appears that the new wind slab fractured (possibly on buried surface hoar) and the fracture stepped down into the older slab, all of which released on a knife-hard rain crust layer that lies at or near the ground all over the western Chugach from warm, early-season storms. The fracture appears to have propagated north along the gully and then down to the ground where the snowpack is shallower. This is a classic terrain trap with a relatively long and narrow debris zone (80-100 feet top to bottom and approximately 900 feet in length). The debris depth ranged from 4-10 feet deep with the deepest deposition in the center of the gully and at the southern end of the avalanche path under the thickest portion of the crown face.

HS-AIu-D2-R4-I/O 1930 Weak layer: rain crust, possibly with surface hoar, stepping down to knife-hard rain crust near ground.


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Flattop avalanche victim identified

NEAR FLATTOP: Snow buries snowshoer a mile from parking lot.


Anchorage Daily News

Published: February 9, 2006

Last Modified: February 9, 2006 at 10:12 AM

A snowshoer, killed Wednesday night when an avalanche swept down from the slopes of a gully beside Flattop Mountain, was identified by authorities Thursday morning as Brian Mulvehill.

Mulvehill, 32, is from Clarksville, Mich., and had lived in Anchorage about five months, according to the Alaska State Troopers.

Authorities said he was buried in an area popularly known as Boy Scout Gully, which for years has been a concern of Chugach State Park rangers because of its easy accessibility and the boom in popularity of backcountry snowboarding and skiing. The region is one of the most popular recreational areas, both in the winter and in the summer, in the Anchorage vicinity.

Anchorage city manager Denis LeBlanc, who was on the scene Wednesday night, said searchers began a massive effort that ultimately involved the Alaska Mountain Rescue Group, the Nordic Ski Patrol, the Anchorage Fire Department and the Alaska State Troopers after a snowshoer reported about 7:30 p.m. that a friend had been swept away by the sliding snow and was missing.

Searchers probed the snow and brought in dogs to help. They reported about 9:30 p.m. that one of the dogs had located the body of the missing man.

"You know, life is so fragile," LeBlanc said. "It's a beautiful night tonight. And Alaskans were out doing what Alaskans love to do. It's just a tragedy."

Authorities on the scene said one of the snowshoers somehow triggered the slide.

The dead man, whose body was flown off the range in a helicopter, had not been identified late Wednesday night.

The avalanche occurred within a mile of the Glen Alps parking lot. "It just goes to show you the mess you can get into right out of the parking lot," said William Laxson with the Alaska Mountain Rescue Group and who was involved in the search effort.

Soren Orley, also with the Alaska Mountain Rescue Group, said it appeared the two snowshoers were en route back to the Glen Alps parking lot and were about 100 feet apart when the avalanche occurred. He said high winds of recent days had loaded the slopes of the gully, which is between Blueberry Hill and Flattop, with snow.

"It was an area that frequently avalanches," said Bill Romberg of Alaska Mountain Rescue Group. "It's not a spot to mess with."

Romberg said the slide appeared to be about 300 yards wide. He said the snowshoers carried no rescue gear with them -- no avalanche beacons, no shovels, no probes.

Authorities said the two were the only ones who appeared to be in the area when the avalanche occurred.

Daily News reporter Megan Holland can be reached at or 257-4343. Outdoors editor Craig Medred contributed to this story.