Mount Baker - Sherman Peak Avalanche 10-21-13

[John_Scurlock]

On October 21, 2013, at about 3 pm local time, a large avalanche occurred off the east face of Sherman Peak on Mount Baker, dumping a large amount of debris into the crater's 'east breach' and on down the Boulder Glacier. It doesn't seem to have been observed by anyone, though it was recorded on two nearby seismic stations. This is a repeat of a periodic event which occurs on intervals of two to five years. The unusual aspect of this particular slide is that it happened so late in the year. Previously it was thought to be a summer phenomena. In this case, the volume of material in the debris flow is thought to be larger than previously observed but the slide also didn't seem to travel as far down the mountain as it has in past years. The depth of material in the east breach is probably about a hundred feet or so, and there is some concern that this buildup might trap some amount of dangerous heavier-than-air gasses in the crater such as CO2 or H2S. This avalanche is a reminder that travel on the Boulder Glacier or in other areas beneath the east face of Sherman peak has a rather serious and unpredictable objective hazard. Here is the Pacific Northwest Seismic Network blog post from Dr Steve Malone:

 

http://www.pnsn.org/blog/2013/10/29/large-mount-baker-debris-avalanche-this-fall

 

And here is the start of eight images taken on October 28 and 29, http://www.pbase.com/nolock/image/153126864 (click 'next' at upper R to see each image in sequence, and click 'original' below an image to see the largest posted size)

 

Sherman peak's east face is a gigantic wind deposition slope, and this scar will fill in over the course of this and next winter, and eventually it will slide again. The cause seems to be simple 'angle of the slope' in combination with a crap-quality substrate, rather than anything related to a volcanic heat related process. That is not known for certain however. For a sense of scale, see this image of Dave Tucker near the 'Sulpher Cone' fumaroles during a volcanic gas-sampling research trip into the crater in 2010: http://www.pbase.com/nolock/image/127437834

 

 

[max]

bad ass!

 

PS: thanks for the information! Your work helps bring the science to the people in an accessible and interesting way.

 

Edited October 30, 2013 by max

[John_Scurlock]

Thxs, Max, honestly it was pure luck I happened to be by there on the 28th, as it was a completely unplanned, spur of the moment and very short flight. It was good detective work by Jackie Caplan-Auerbach from the geology department at WWU to find the event in the recent seismic record.

 

By the way, the duration of the seismic signal has been measured at 71 seconds. It would have been awesome to see it happen, provided you were located at a safe vantage point..

[JasonG]

Thanks John, fascinating! There was also an event in 2010. I was up on Anderson Butte with the family and took this photo in early September of that year:

 

 

 

 

When that thing goes, the scale is pretty incredible.