Tuesday, January 17, 2017
Monday, January 16, 2017
Location Name or Route:
Gravel Pit Lanes
Trigger: additional info:
Persistent Weak Layer
This morning at the Geyser Pass TH I ran into the party of two that triggered this slide sometime after 3 PM on Monday 1/16/17. I think the rider that triggered the slide was on a snowboard, but I am not 100 percent sure. They told me that Rider 1 triggered the slide and it broke at his feet. He was not carried down slope. Rider 2 was above Rider 1 and was not affected by the slide. Rider 1 descended the bed surface and Rider 2 traversed to skiers left and descended the steep rollover above Tele Heaven. See the photos below for their route off the ridge line that leads to the summit of Tuk No. They skied a more conservative line in the glades on Sunday 1/15/17, but this time they took a line higher up the ridge and more towards skiers right. They entered the steepest part of the gully in the middle of Gravel Pit Lanes. This section has rocks and a very steep rollover. It also faces due north. The snowpack is somewhat shallow in this area. I walked up the bed surface, but was unable to make it to the crown because it was quite steep and rocky. I was maybe 100 feet below the crown. From my vantage point I sighted the slope at the crown around 40 degrees. I can generally sight within 2 degrees so it is safe to say the slope at the crown is between 38 and 42 degrees. The suspected weak layer is facets. The snowpack here is shallow and rocky and is a very likely spot to find faceted snow. The slope also appears to have been cross loaded. So you have windslab sitting on the weak facets and it failed under the weight of the skier. The slide ran maybe 600 feet and 150 feet wide. The debris buried the party's skin track and also several tracks below on Tele Heaven. The party said they would report the incident, and I hope we get a first hand account from them of what happened.
Here's a shot of their tracks from their drop in point off the ridge line. They headed far skiers right and into the steep gully. The gully is seen in the shadows.
Looking up the debris pile towards the crown.
Some closeups of the crown. And in the last shot you can clearly see the slope cut leading right into the crown.