Feb 062017
 

With all the precipitation in the Rockies this year (we’re at +153% normal snowpack at the moment), we thought we would re-release a publication that highlights at least one important aspect of Colorado snowfall — that is, the significant danger of avalanches. The Snowy Torrents: Avalanche Accidents in the United States 1980-86, compiled and written by Nick Logan and Dale Atkins and illustrated with Larry Scott’s fine pencil drawings, was first published in 1996. We still have a few hard-copies available and, because of that, yes, we do charge for the PDF download. However, Larry went back and re-made the PDF from the original publication file, producing a file that is far better than the rather poor digital scan we had offered previously.

The volume details 146 oft-times harrowing stories surrounding avalanches, the lives they claim, survivors and witnesses, along with assessments as to what happened, why it happened, and what could have been done to prevent loss of life and/or property. The authors are never judgmental, and their clear-eyed accounts contain a wealth of wisdom that will add to the knowledge-base of any winter backcountry enthusiast.


Citation: Logan, Nick, and Dale Atkins. SP-39 The Snowy Torrents: Avalanche Accidents in the United States, 1980–86. Special Publications 39. Denver, CO: Colorado Geological Survey, Department of Natural Resources, 1996.
Feb 012017
 

By Jill Carlson

On March 23, 2003, a large avalanche occurred about one mile west of the Town of Silver Plume. The avalanche brought trees, rock, soil and snow to the valley floor, knocked down overhead utility lines, blocked the I-70 frontage road, damaged the town’s water treatment plant (WTP), and dammed Clear Creek. The dam was breached using explosives before the plant’s electric pump motors were flooded. With damage to the WTP’s chlorine contact tank and building, Silver Plume residents had to boil their tap water for over a month.

The avalanche occurred three days after near-record snowfall. It was triggered by additional snow loading in the starting zone caused by a change in wind direction, and began in a known avalanche path above timberline on Pendleton Mountain. Its unusually large volume and velocity caused it to unexpectedly reach the valley floor, along a path not previously identified as an avalanche chute. Rick Gaubatz, the Town’s water commissioner, counted 110 rings in a spruce tree that was found in the avalanche debris at the damaged WTP, indicating that an avalanche of similar magnitude had not occurred in the immediate area in at least 110 years.

Avalanche debris in the runout zone taken by Xcel Energy from a helicopter on the morning after the avalanche occurred, 24 March, 2003.

Avalanche debris in the runout zone taken by Xcel Energy from a helicopter on the morning after the avalanche occurred, 24 March 2003.

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Jan 232017
 

The CGS’s Matt Morgan and Jon White were two of the co-authors on one of the top-ten Geological Society of America (GSA) 2016 book chapters and journal articles, this out of 600 papers. The article describes a comprehensive forensic analysis of the massive West Salt Creek rock avalanche that occurred in late May 2014 in western Colorado (USA). The analysis relied on large-scale (1:1000) structural mapping accomplished via high-resolution unmanned aircraft system imagery along with seismic data generated by more than twenty stations within approximately 500 miles (800 km) of the event. The avalanche was the largest mass-movement slope failure in the historical record of Colorado, and it killed three people, narrowly avoiding destroying a gas wellhead.


Citation: Coe, Jeffrey A., Rex L. Baum, Kate E. Allstadt, Bernard F. Kochevar, Robert G. Schmitt, Matthew L. Morgan, Jonathan L. White, Benjamin T. Stratton, Timothy A. Hayashi, and Jason W. Kean. 2016. “Rock-Avalanche Dynamics Revealed by Large-Scale Field Mapping and Seismic Signals at a Highly Mobile Avalanche in the West Salt Creek Valley, Western Colorado.” Geosphere 12 (2): 607–31. doi:10.1130/GES01265.1.