Jump to content

Hyak Avalanche


Hugh Conway

Recommended Posts

  • Replies 36
  • Created
  • Last Reply

Top Posters In This Topic

The fracture in the first photo suggests the lift poles would have been taken out, but then the chairs can still be seen on the upper portion of cable, which suggests the lift is still intact. The WSDOT angle doesn't address this.

Anyone have more data?

 

Oh, Mtn Gods, please don't wipe out Alpental, please take Summit West instead! Heck, we'll even throw in most of Central...

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.

Link to comment
Share on other sites

I can't really discern much in any of the photos. I think in reality what it probably could best be described as: a sub-snow pack mudflow (almost a joukuloup sinso-stricto)releasing somewhere on the eastern portion, which caused a large slab avalanche to propagate to the west, and uphill.

******************************************************************

 

When I was in my twenties, the term joukuloup was confined to sub glacial debri torrents presumably caused by volcanic and hydro-thermal heat sources. I understand that the usage of the term is now much more liberal

Link to comment
Share on other sites

I have never heard the term jökulhlaup used for anything but glacial outburst floods eg. the Ape Lake jökulhlaup down the Noieck River. there is no glacier and indeed, very little evidence of water flow in the debris which appears to mix snow and mud.

 

I agree with you though, a debris slide beginning under the snow and carrying the overlying snowpack with it with secondary slab failure propagating from that.

Link to comment
Share on other sites

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...