Slab avalanche


Slab avalanche – showing starting zone, track, and runout.

This avalanche was only a meter or 2 high and occurred in what appeared to be a reservoir for snow-making at Eldora Mountain Resort, hence the plastic underlay. The slope is on the leeward side of the “mountain”; note the cornices to the left of the avalanche.


That’s not an avalanche - it’s a “slump” or sometimes a “slide” - see http://oaklandgeology.files.wordpre[…]pdiagram.jpg for an illustration - see also the picture just above it at

Lots of California hillsides have these little blowouts on them…sometimes they’re not so little.

I thought of it as an avalanche in microcosm. Why is it not?

That’s not a slab avalanche. Anyone can see it’s the remains of Noah’s ark! What’s wrong with you guys?

Matt Young said: I thought of it as an avalanche in microcosm. Why is it not?

Primarily because it didn’t go anywhere. According to Wikipedia ( “An avalanche is a rapid flow of snow down a slope” Avalanches have common elements including “…a slide path along which the avalanche flows, a run out where the avalanche comes to rest, and a debris deposit which is the accumulated mass of the avalanched snow once it has come to rest.

That large flat structure in the picture is not a slide track - its just the now-unattached surface of the snow pack - you can see still-attached similar surfaces further to the left.

I don’t see much difference between this baby avalanche and the animation at the link. Is the distinction that the top of the debris field didn’t get past the starting zone?

Incidentally, does an avalanche have to grow as it goes down, like an electron avalanche? I could find no statement to that effect while looking up avalanches for this posting.

I hope the little tiny skiers and little tiny snowmobiles got away OK.

Was this avalanche started with explosive charges? The rest of the slope looks pretty dangerous;)

GaryB said:

I hope the little tiny skiers and little tiny snowmobiles got away OK.

They might have been tarped under all that snow!

I think you nitpickers are so hard up for nits that you are grasping at dandruff. Isn’t one of the wonderful things about nature its scalability? You could just as easily say that the hill slides are not avalanches because they don’t involve snow. Anyway the micro-avalanche clearly has all three parts needed to make it an avalanche. It also lacks something that defines the hill slide such that I am tempted to say the hill slide is not an avalanche. The definition for the slump of a hill slide included a ‘scalloped’ shaped depression. An avalanche clearly doesn’t require such and is therefore not a hill slide.

Given the slippery plastic underlay how does this have any bearing on reality? Sort of “synthetic” situation, wouldn’t you say?


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This page contains a single entry by Matt Young published on December 21, 2009 12:00 PM.

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