Jump to content

Hyak Avalanche


Hugh Conway

Recommended Posts

  • Replies 36
  • Created
  • Last Reply

Top Posters In This Topic

From the final approved plan:

Summit East

 

* New Rampart Quad Chair (front side of Hyak)

* New Mill Creek Triple Chair (back side of Hyak)

* Replacement/realignment of Keechelus with Mt. Hyak High Speed Quad

* Night skiing at Rampart and Mill Creek chairs

* Mountain-top restaurant

http://www.summit-at-snoqualmie.com/info/winter/mdp.asp

 

Link to comment
Share on other sites

I was gonna say, looks more like a debris flow than an avalanche - looks like WSDOT beat me to it.

 

But, both the top and at least the upper 1/2 of the western side are defined by a snow-slab fracture. The upper 1/2 of the sliding surface appears to be planar. The NWAC has been stating that 100% climax slab avalanches are probable given the dynamics of this snow pack. So I would say that it was a slab avalanche with the decollement being a wet relatively smooth grassy surface with possibly a surface hoar layer immediately above. The debris could be expected whenever such a large wet strata is involved in a structural failure.

 

I would also add, that in a failure of this sort, as wether it is a slab causing a debris flow, or a mud flow triggering a slab avalanche is mostly arguing semantics.

 

I went up and looked at this yesterday. Two guys were skiing down and stopped to talk to me. One of the guys said he lived by the treatment plant and witnessed the whole thing. He told me that there is a guy who has lived at Hyak for 50 years who made mention that when they leveled the ground under the lift towers that fill dirt was brought in, which was a compost of sorts. A slurpy mixture of old rotted tree stumps and moraine like rock gravel is the result going down the mountain.

 

From looking at the event up close you can indeed tell it is NOT an avalanche, but was the result of total ground collapse underneath the snowpack. The hole looks more like a bomb crater than anything. The fact that there is a crown in the snow, is only a result of the underlying surface blowing out.

 

I hope they shut the area down and build a gondola to the top of Snoqualmie Mountain.

Link to comment
Share on other sites

  • 2 weeks later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.




×
×
  • Create New...