Human Triggered Avalanche, 600FT X 350FT, 12″ DEEP | First Of Season For Chugach, AK

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Human Triggered, hard slab avalanche, Chugach State Park, AK. Image: Anchorge Avalanche Center(AAC), 10/28/17

Anchorage Avalanche Center , Chugach State Park, Alaska, just saw a very large early season avalanche on Saturday. They issued the following report of a recorded observation of the first human triggered avalanche report in the Park this season.

“First reported human triggered avalanche of the season in Chugach State Park (Front Range – Powerline Valley – South Ship Lake Pass) yesterday (Saturday). Beware of the weak early season snowpack. There are multiple weak layers and interfaces across the park that have been buried by recent snowfall and wind loading. It is especially important to keep terrain traps and exposure in mind this time of year; even if an avalanche isn’t large enough for burial it can take you for a brutal ride.” Facebook, Anchorage Avalanche Center, 10/29/17


October 28, 2017

Chugach State Park – Front Range – Powerline Valley – South Ship Lake Pass

Human triggered hard slab avalanche.  Early season Chugach State Park snowpack is extremely variable and weak with multiple weak layers and interfaces (basal facets and depth hoar, melt-freeze crusts, buried surface hoar and faceted layers).  Recent dense wind slabs have developed on top of these weak layers and interfaces.  Weak layers and interfaces are widespread, and proving reactive to human triggers.

Avalanche details

TRIGGER Foot Penetration AVALANCHE TYPE Hard Slab ASPECT Southwest
WIDTH  600ft LENGTH  350ft

Obvious signs of instability



Active wind loading: wind slab developing over hard, slick melt-freeze crust (weak interface) and area of old exposed near-surface facets.

Snow surface

Highly variable: dense wind-packed, soft powder, hard melt-freeze.


Extremely variable.

Chugach State Park, Avalanche location
Chugach State Park, AK

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