Thursday, March 06, 2014

Big Avalanches on the Nisqually (Rock AND Snow)

Late in February, we received word from the Pacific Northwest Seismic Network and the University of Washington that there had been a noticable surface seismic event (not an earthquake) that appeared to be near the top of the Nisqually Cleaver.  You may recall that in the summer of 2012, a large portion of the Nisqually Cleaver gave way at about 12,000 feet and tumbled down to about 8000 feet on the Nisqually Glacier.  This wasn't as big, but nevertheless the PNSN and the UW gave us a heads up and asked if anyone had seen anything. 

You can see the brownish stain on the surface of the glacier below the Nisqually Cleaver.  This is exactly where the large rock avalanche occurred in 2012. However, what was more noticeable was a snow avalanche that occurred from the 11,500 foot level on the Nisqually Icefall and traveled all the way down to the terminus of the Nisqually Glacier.  I have seen avalanche debris on the Nisqually down to about 6500 feet before, but never down to the terminus!

The following images were taken on Friday February 28th from the Muir Snowfield:

Snow in Red. Rock in Blue.
Debris approaching terminus of Nisqually